Stratigraphic Micropalaeontology of Atlantic Basin and Borderlands (Developments in Palaeontology and Stratigraphy)

STRATIGRAPHIC MICROPALEONTOLOGY OF ATLANTIC BASIN AND BORDERLANDS

FURTHER TITLES IN THIS SERIES 1. A.J. Boucot EVOLUTION AND EXTINCTION RATE CONTROLS

2. W.A. Berggren and J.A. van Couvering THE LATE NEOGENE - BIOSTRATIGRAPHY, GEOCHRONOLOGY AND PALEOCLIMATOLOGY O F THE LAST 1 5 MILLION YEARS IN MARINE AND CONTINENTAL SEQUENCES 3. L.J. Salop PRECAMBRIAN OF THE NORTHERN HEMISPHERE

4. J.L. Wray CALCAREOUS ALGAE 5 . A. Hallam (Editor) PATTERNS OF EVOLUTION, AS ILLUSTRATED BY THE FOSSIL RECORD

This book is produced by a photographic offset process directly from the manuscript. Thus. the publisher is not responsible for any errors appearing in the book.

Developments in Palaeontology and Stratigraphy, 6

STRATIGRAPHIC MICROPALEONTOLOGY OF ATLANTIC BASIN AND BORDERLANDS Edited by

F.M. SWAIN Department of Geology, University of Delaware, Newark, Del. ( U . S . A . ) and Department of Geology and Mineralogy, University of Minnesota, Minneapolis, Minn. (U.S.A.)

ELSEVIER SCIENTIFIC PUBLISHING COMPANY 1977 Amsterdam - Oxford - New York

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Main e n t r y under t i t l e : S t r a t i g r a p h i c rricropaleontology of A t l a n t i c b a s i n and border l a n d s . (Developments i n palaeontology and s t r a t i g r a p h y ;

5) Papers p r e s e n t e d a t a symposium supported by and convened a t t h e U n i v e r s i t y of Delaware, J u n e 14-16,

1976. Bibliography: p. InclJides indexes. 1. Eicropaleontology--Worth A t l a n t i c Oceany--~o~t~ Congresses. 2. ~ ~ c r o ~ a l e o ~ ’ t o l o g y A-nerica-Conpeesses. 5 . Geology, S t r a t i g r a p h i c - - C o n g r e s s e s . 1. Geology--North A t l a n t i c Ocean--Congresses. 5. G e o l o p - - N o r t h America--Congresses. I. Swain, 11. Delaware. F r e d e r i c k M o r n l l , 1916U n i v e r s i t y , Newark. 111. S e r i e s . QE719.S83 560’ .921 77-915 ISBN

0-444-41554-8

0 Elsevier Scientific Publishing Company, 1 9 7 7 .

All rights reserved. No part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, without the prior written permission of the publisher, Elsevier Scientific Publishing Company, P.O.Box 330,Amsterdam, The Netherlands

Printed in The Netherlands

V

PREFACE A symposium on the stratigraphic micropaleontology of the Atlantic basin and margins was convened at the University of Delaware, June 14-16, 1976. The symposium was attended by 56 people, and 27 papers were presented. The volume represents the published proceedings of the symposium and consists of 26 papers by 28 authors. Although a serious attempt was made to provide at least minimum coverage of all major micropaleontologicd groups in and around the Atlantic, these efforts were not successful in the case of diatoms, Paleozoic calcareous Foraminifera, coccoliths and Paleozoic and Cenozoic palynology. The volume includes summaries and discussions of the stratigraphic and geographic distribution of Paleozoic, Mesozoic and Cenozoic Foraminifera, Radiolaria and Ostracoda; Paleozoic and Mesozoic conodonts; Paleozoic Chitinozoa and acritarchs; Mesozoic dinoflagellates, and palynomorphs; and Cenozoic silicoflagellates. The discussions of individual papers represent transcripts of tapes made at the meeting, written questions submitted at the meeting, and subsequent modifications of questions and answers by questioners and authors, through correspondence. Several participants in the symposium were unable t o submit final manuscripts or plan t o publish their papers elsewhere; G.L. Williams and J.P. Bujak, Geological Survey of Canada (Cenozoic palynology ), Stefan Gartner, Texas A. and M. University (Cenozoic coccoliths), F.M. Gradstein, Geological Survey of Canada (Jurassic Foraminifera), and Piero Ascoli, Geological Survey of Canada (Biostratigraphy of Scotian Shelf). The papers on South Atlantic Cretaceous Ostracoda and Paleogene and Neogene Foraminifera contain more details on localities than most of the other papers. I t was decided t o retain this information because some of it is not easily accessible t o workers in the Northern Hemisphere. It was originally planned that a summary chapter be prepared on Atlantic stratigraphic micropaleontology, with the collaboration of all the authors. Limitations on the length of the book have prevented this being done. ACKNOWLEDGEMENTS

I am greatly indebted t o the Graduate School and the College of Arts and Sciences of the University of Delaware for support of the symposium and to Dr. John C. Kraft, Chairman of the Geology Department who made the arrangements for support. Michelle Mayrath prepared illustrations for my ostracode and acritarch papers, and also provided invaluable assistance in editorial matters. Teresa Grilli typed or re-typed many of the manuscripts. Patricia Barlow, Barbara Frank, and Sarah Cornell also assisted in secretarial and editorial work. F.M. SWAIN

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VII

CONTENTS Preface . . . . . . . . . . . . . . . . . . . . . . . . Early Paleozoic Ostracoda of Eastern Canada. M.J. COPELAND . . . . . Early Paleozoic Ostracoda of the Atlantic Margin. other than Eastern Canada. F.M. SWAIN . . . . . . . . . . . . . . . . . . . . . Paleozoic Smaller Foraminifera of the North American Atlantic Borderlands. JAMES E CONKIN and BARBARA M CONKIN . . . . . . . . . Late Paleozoic Ostracodes of Western Europe and North America: A Review. LUIS C SANCHEZ DE POSADA . . . . . . . . . . . . . . Early Paleozoic Conodont Biostratigraphy in the Atlantic Borderlands. STIG M. BERGSTROM . . . . . . . . . . . . . . . . . . . Late Paleozoic and Triassic Conodont Biostratigraphy : Correlations around the Expanding Atlantic Ocean. DAVID L CLARK . . . . . . . . . . Notes on Paleozoic Acritarchs from the Atlantic Margins. F.M. SWAIN . . . Paleobiogeography of Chitinozoa. D W. ZALUSKY . . . . . . . . . Paleozoic Radiolaria: Stratigraphic Distribution in Atlantic Borderlands. B.K. HOLDSWORTH . . . . . . . . . . . . . . . . . . Autunian and Carnian Palynoflorules: Contribution to the Chronology and Tectonic History of the Moroccan Pre-Atlantic Borderland. HAROLD L . COUSMINER and WARREN MANSPEIZER . . . . . . . . . . Mesozoic Foraminifera - '8,stern Atlantic. RICHARD K . OLSSON . . . . Jurassic Ostracoda of the Atlantic Basin. R.H. BATE . . . . . . . . . Cretaceous Ostracoda of the North Atlantic Basin. JOHN W NEALE . . . Cretaceous Ostracoda - South Atlantic. ALWINE BERTELS . . . . . . Mesozoic Radiolaria from the Atlantic Basin and its Borderlands. HELEN P FOREMAN . . . . . . . . . . . . . . . . . . . . . Jurassic Palynostratigraphy of Offshore Eastern Canada. JONATHAN P. BUJAK and GRAHAM L WILLIAMS . . . . . . . . . . . . . Comparison of Lower and Middle Cretaceous Palynostratigraphic Zonations in the Western North Atlantic. DANIEL HABIB . . . . . . . . . Upper Cretaceous Dinoflagellate Zonation of the Subsurface Toms River Section Near Toms River. New Jersey. RICHARD AURISANO and DANIEL HABIB . . . . . . . . . . . . . . . . . . . . North Atlantic Cenozoic Foraminifera. W.A. BERGGREN . . . . . . . Paleogene Foraminifera - South Atlantic. ALWINE BERTELS . . . . . Neogene Foraminifera - South Atlantic. ALWINE BERTELS and MARLY MADEIRA-FALCETTA . . . . . . . . . . . . . . . . Cenozoic Ostracoda - North Atlantic. M.C. KEEN . . . . . . . . . Cenozoic Marine Ostracoda of the South Atlantic. W.A. VAN DEN BOLD . Cenozoic Radiolarians of the Atlantic Basin and Margins. RICHARD E CASEY and KENNETH J. McMILLEN . . . . . . . . . . . . Atlantic Cenozoic Silicoflagellates. Potential for Biostratigraphic and Paleoecologic Studies. RICHARD E . CASEY . . . . . . . . . . . . North American Microtektites. Radiolarian Extinctions and the Age of the Eocene-Oligocene Boundary. B.P. GLASS and MICHAEL J . ZWART . . Index t o Authors . . . . . . . . . . . . . . . . . . . . . Index t o Genera and Species . . . . . . . . . . . . . . . . .

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* . v . . 1 19

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49 61

. .

85

. . . . . .

111 131 151

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. 167

. . 185 . . 205

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. 231 . 245 . 211

. 305 .

321

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341

. 369 . 389 . 411 . . .

. 441 . 461 .

495

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521

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. 545

. . 553 . . 569 . . 511

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1 EARLY PALEOZOIC OSTRACODA OFEASTERN CANADA

M . J. Copeland Geological S u r v e y of Canada, Ottawa, Ontario, K1A OE8 Abstract Pre-Middle Devonian OStrQCodQo c c u r in three northeast-trending s t r u c t u r a l provinces of eastern Canada. They comprise biogeographically a n d stratigraphical ly distinctive leperditicopid, palaeocopid and podocopid assemblages dominated by Ordovician hollinids in the n o r t h e r n (Anticosti Basin) province a n d by SiluroDevonian beyrichiids in all three provinces. Correlation is possible only between endemic North American Early Silurian beyrichiid assemblages of the n o r t h e r n and central (Appalachian Belt) provinces; the s o u t h e r n ( F u n d y Belt) province displays the typical Beyrichienkal k fauna of n o r t h e r n Europe. Introduction S o continuous sequence of pre-Middle Devonian palaeocopid or podocopid

ostracode faunas h a s been d e s c r i b e d from e a s t e r n Canada. T h i s is d u e i n p a r t to facies variation and discontinuities i n the geological r e c o r d b u t it is anticipated that future study will reveal a more complete zonation than is now possible. Distinct depositional, temporal, geographic and tectonic control is evident, however, i n the ostracode assemblages presently known.

These faunas a r e

contained i n t h r e e generally parallel s t r u c t u r a l provinces comprising a n older platformal sequence i n Anticosti Basin and two y o u n g e r , shallow water sequences, those of the "Appalachian Belt" i n Gasp6 Peninsula and s o u t h e r n Quebec and the "Fundy Belt" of Maritime Canada and coastal New England ( F i g u r e 1 ) . Assemblages of North American aspect occur on either s i d e of the n o r t h e r n limit of Acadian orogenic deformation. The n o r t h e r n , undeformed St. Lawrence Platform

-

Antieosti Basin faunal sequence reflects a n initially provincial Middle

Ordovician ostracode assemblage, modified somewhat b y Late Ordovician boreal elements, and a subsequently endemic North American Early Silurian ostracode fauna of Appalachian aspect. T h i s endemic fauna, b e a r i n g the only palaeocopid ostracodes presently known to provide correlation a c r o s s the Acadian Front (Figure 2 ) , also o c c u r s i n basal s t r a t a of the deformed Silurian sequence i n Gasp6 Peninsula and m a r k s initiation of the typical northeastern North American Siluro-Devonian Appalachian Belt ostracode succession. It differs completely from the more stratigraphically restricted European beyrichiid fauna of t h e Fundy Belt to the south. These faunas a r e separated i n central New Brunswick b y a

2

EASTERN CANADA Early Paleozoic Sedimentary Basins

1. Port-au-Port Peninsula 4. 7. 10. 13.

Anticosti Island Dalhousie Arisaig E a s tpor t

2. 5. 8. 11. 14.

Table Point 3. Forillon Peninsula 6. Lake Matapedia 9. Portapique River 12. Coast of JIaine (general) 15.

Mingan Islands Mt. Albert area Rloose River Synclinorium Jones Creek Newbury port

Figure 1. Early Paleozoic structural provinces of eastern Canada and northeastern United States, with localities mentioned. wide zone of Silurian turbidites that may represent a marine trough that effectively separated contemporaneous ostracode faunas of North American and European aspect. The time-restricted Late Silurian-Early Devonian Fundy Belt assemblage, of distinctive north European Beyrichienkalk affinity, is contained in a segment of the European continental plate, left behind after collision with the North American plate had resulted in closure of the proto-Atlantic Ocean and its subsequent reopening during the Mesozoic.

3

1

NORTH

I

I

UNDETORMCD

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LAWRCMCE

LOWLAND and Q Y t b W !

AMTICOSTI MAS111

Ionfarlo

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AMERICAN

-

DCFORYCO

APPALACHIAN

I V

MELT

EUROPEAN

A C A D I A M OROGCMV

TUNDV

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, Y

Figure 2 . Faunal and tectonic relationships of ostracode assemblages recognized in eastern Canada History of Investigations Ostracoda have been recorded from relatively few localities in Anticosti Basin (Fig. 1, locs. 1-4). Chief among the early investigators were Billings (1865, 1866) and Jones (1858, 1890a,b, 1891).

During the present century, Ulrich and

Bassler (1923), Bassler (in Twenhofel, 1 9 2 8 ) and Copeland (1970a, b, 1973, 1974a) presented a Late Ordovician and Early Silurian ostracode zonation for Anticosti Island, and Berdan ( i n Whittington and Kindle, 1963) reported on a Middle Ordovician fauna from western Newfoundland (Fig. 1, loc. 2 ) .

Additional

information on younger Early Paleozoic ostracode faunas may be forthcoming when samples of strata from beneath the Gulf of St. Lawrence between Anticosti

4

Island, Quebec (Fig. 1, loc. 4 ) and Port-au-Port Peninsula, Newfoundland (Fig. 1, loc. 1) a r e studied. Middle Ordovician ostracode faunes from St. Lawrence Lowland and related areas surrounding the Precambrian shield of eastern Canada a r e recorded in Kay (1934), Carter (1957) and Copeland (1965, 1970a, 1976, in p r e s s ) , This is probably the most extensively distributed Early Paleozoic ostracode fauna in northern North America a s it i s also reported from Yukon Territory and Districts of Mackenzie and Franklin (Copeland, 1974b, in p r e s s ) , Within the Appalachian Belt the earliest report of Devonian ostracodes was by Jones (1889) from collections made along the southern shore of Chaleur Bay in northern New Brunswick (Fig. 1, loc. 7 ) .

This fauna was redescribed and

numerous additional species were recorded by Clarke (1909) and Copeland (1962) from the vicinity of Campbellton and Dalhousie, New Brunswick. In northern Maine, south of Quebec City, Berdan (in Boucot, 1961) reported a small beyrichiid fauna from the Moose River Synclinorium (Fig. 1, loc. 9) that has proved slightly older than an Early Devonian fauna from Forillon Peninsula (Fig. 1, loc. 5) that was identified independently by Berdan and Copeland and reported in Burk (1964) and Boucot (1965). Because of its European aspect, ostracode faunas from the Fundy Belt (Fig. 1, locs. 10-15) attracted the attention of several early workers during the midnineteenth century. Honeyman (1859, 1864), Dawson (186G, et seq. ) , Hall (1860) and Jones (1870, 1881a, b ) each recorded part of this Beyrichienkalk fauna from Xrisaig, Nova Scotia (Fig. 1, loc. 1 0 ) . In this century, McLearn (1924) and Copeland (1960, 1964) defined the position of this fauna within the thick stratigraphic sequence present in that area. Only recently have additional localities been reported in Nova Scotia and New Brunswick (Fig. 1, locs. 11. 1 2 ) , and Berdan (1966, 1971, in Brookins et a l . , 1973) recorded a longer ranging ostracode fauna from coastal Maine (Fig. 1, locs. 13, 1 4 ) extending southwestward to Massachusetts (Fig. 1, loc. 15). r h z Ostracode Fauna The earliest ostracode fauna of St. Lawrence Lowland-Anticosti Basin is Whiterockian (Llanvernian) of the Table Head Formation of western Newfoundland.

' E o l e p e r d i t i a ' of the general 'Eoleperditia' bivia (White) group i s most significant in that it represents a circum-cratonal North Americar. platform fauna that occurs

5 also in Nevada and southwestern District of ., a n d Whitfield (1890) to m e n t i o n a, few. During t h e e a r l y d e c a d e s of t h e t w e n t i e t h c e n t u r y major European w o r k s included t h o s e by Bonnema (1909) a n d K u m m e r o w (1924). In t h e United States s i g n i f i c a n t works included t h o s e of Ulrich and Bassler (1908, 1913a, 1913b, 19231, S w a r t z (1932, 1933, 19361, a n d K a y (1934, 1940). In Europe m a j o r p a p e r s on Ordovician and Silurian o s t r a c o d e s in Scandinavia a n d t h e B a l t i c region w e r e published by Hessland (19491, Henningsmoen (1953a, 1953b,' 1954a, 1954b, 1 9 5 4 ~ )J a a n u s s o n (1957) a n d Sarv (1959). In t h e U n i t e d S t a t e s p a p e r s d e a l i n g w i t h Ordovician a n d

20

Silurian o s t r a c o d e s include: S w a r t z a n d W h i t m o r e (1956); Swain (1953, 1957, 1962). In s u b s e q u e n t y e a r s m a n y p a p e r s h a v e a p p e a r e d o n European Ordovician a n d Silurian o s t r a c o d e s as discussed below, b u t only a f e w in t h e U n i t e d S t a t e s . For t h e l i t e r a t u r e on C a n a d i a n f a u n a s see Copeland (this volume). This a r t i c l e will briefly r e v i e w t h e major e a r l y P a l e o z o i c o s t r a c o d e f a u n a s of t h e A t l a n t i c margins o t h e r t h a n t h o s e of C a n a d a which a r e d e a l t w i t h by Dr. Murray Copeland, herein. Cambrian Archaeocopids o c c u r t h r o u g h o u t t h e C a m b r i a n S y s t e m in t h e United Kingdom; In t h e e a r l y C a m b r i a n , A l u t a , Beyrichiona, Bradoria, Dielymella, a n d Indiana a r e represented-bold a n d Pocock, 19 34; Cobbold, 1936). T h e middle C a m b r i a n contains, in a d d i t i o n , Entomidiella?, Hipponicharion, a n d S v e a l u t a (Cobbold a n d Pocock, 1934; Jones, 1856; Taylor a n d R u s h t o n X T h e l a t e C a m b r i a n h a s yielded C y c l o t r o n , F a l i t e s , Hesslandona, a n d f u r t h e r to t h e preceding: Vestro o t h i a (A. W. A. Rushton, w r i t t e n c o m m u n i c a t i o n , 6 F e b r u a r y

+

E l s e w h e r e in t h e A t l a n t i c borderlands, a r c h a e o c o p i d s a r e poorly known. A f e w o c c u r in t h e e a r l y a n d middle C a m b r i a n of m a r i t i m e C a n a d a (Copeland t h i s volume) a n d New York (Ulrich a n d Bassler, 1931). Ordovician The distribution of Ordovician O s t r a c o d a a r o u n d t h e "ProtoAtlantic" O c e a n is shown in F i g u r e 1. The c o n t i n e n t a l r e c o n s t r u c t i o n i s f r o m Smith, Briden, a n d D r e w e r y (1973). Early Ordovician Early Ordovician C a n a d i a n (Trernadocian? + Arenigian) o s t r a c o d e s a r e poorly known f r o m e a s t e r n N o r t h A m e r i c a , b u t isochilinids such as I.' g r e g a r i a (Whitfield) (Table 1, fig. 2-11) Isochilina s e e l y i I, fig. ( W h i t f i e l a (Table I, fig. 2-12) a n d I. c r i s t a t a (Whitfie1-e 2-10) and e o l e p e r d i t i i d s a r e r e p r e s e n t e d in c a r b o n a t e f a c i e s (Whit field, 1890, Bassler -and K e l l e t t , 1934). Undescribed leperditellids a n d o t h e r s m a l l e r s p e c i e s o c c u r in t h e c a l c i t i c facies (Swain, 19571, b u t widespread e a r l y Ordovician d o l o m i t e s a r e b a r r e n of o s t r a c o d e s . Isochilinids also o c c u r in t h e Arenigian of n o r t h e r n G r e e n l a n d (Poulsen 1929, 1934).

21

In Sweden (Hessland, 19491, a diverse early Arenigian ostracode assemblage includes Conchoides minuta Hessland (Table I, fig. 2-5) and related species, Glossomorphites tenuilimbata (Hessland) (Table I), and related forms, Primitiella brevisulcata Hessland (Table I, fig. 2-17), Aulaco sis spp. (Table I, gifProtallinella rewin ki (Bock) Table I, fig. 2-18), and others. The Arenigian of Norway Asaphus Series) has yielded a variety of beyrichiacean ostracodes in a mainly shaly facies (Henningsmoen, 1954a). In Wales and central England entomidellids, beyrichiids, and tetradellids have been recorded from Arenigian beds (Table I, fig.2). Additional early Ordovician ostracodes not mentioned above a r e listed in Table 1 and illustrated in figure 1 (Henningsmoen, 1954a; Ulrich and Bassler, 1908; Jones, 1884). An important early Ordovician ostracode fauna has been described from the Estonian S.S.R. (Sarv, 1959)

T---e

g__pf

22

Figure 2 1. 2.

3. 4. 5.

6. 7.

8. 9. 10.

11. 12.

13. 14. 15.

16. 17.

18. 19. 20.

Aulacopsis b i f i s s u r a t a Hessland. R i g h t valve, x23, e a r l y Ordovician,’ Leskusanget, Sweden (Hessland, 1949). Aulacopsis m o n o f i s s u r a t a Hessland. R i g h t valve, x23, e a r l y Ordovician, S t e n b e r g , Sweden (Hessland, 1949). Beyrichia b a r r a n d i a n a Jones. L e f t valve, x3, e a r l y Ordovician, Mynyddgarw, Wales ( J o n e s , 1885). C e r a t o c y p r i s longispina Hessland. R i g h t valve, x23, e a r l y Ordovician, L e s k u s a n g e t , Sweden (Hessland, 1949). Conchoides m i n u t a Hessland. R i g h t valve, x23, e a r l y Ordovician, S t e n b e r g , S w X c H e s s l a n d , 1949). C t e n e n t o m a p l a n a Hessland. R i g h t valve, x23, e a r l y Ordovician, Leskusanget, Sweden (Hessland, 1949). Entomidella m a r r i i Jones. R i g h t valve, x1.5, e a r l y Ordovician (distorted), N a n t l l e , Wales (Jones, 1884). Eurychilina d o r s o t u b e r c u l a t a Hessland. R i g h t valve, x23, e a r l y Ordovician, Silberberg, Sweden. (Hessland, 1949). Glossopsis d e p r e s s o l i m b a t a Hessland. R i g h t valve, x23, e a r l y Ordovician, Leskusanget, Sweden (Hessland, 1949). Isochilina c r i s t a t a (Whitfield). R i g h t v a l v e x8, e a r l y Ordovician, L a k e C h a m p l a i n , V e r m o n t (Swain, 1957). Isochilina g r e g a r i a (Whitfield). R i g h t valve, x6, e a r l y Ordovician, L a k e C h a m p l a i n , Vermont (Swain, 1957). Isochilina s e e l y i (Whitfield), L e f t valve, x6, e a r l y Ordovician, L a k e C h a m p l a i n , Vermont (Swain, 1957). Laccochilina d o r s o p l i c a t a Hessland. R i g h t valve, x23, e a r l y Ordovician, Silberberg, Sweden. Nanopsis n a n e l l a (Moberg and Segerberg). R i g h t valve, x38, e a r l y Ordovician, S l e m m e n s t a d , Norway (Henningsmoen, 1954). Ogmoopsis n o d u l i f e r a Hessland. R i g h t valve, x23, e a r l y Ordovic i a n , Silverberg, Sweden (Hessland, 1949). P i n n a t u l i t e s p r o c e r a (Kurnmerow). R i g h t valve, x23, e a r l y Ordovician, L e s k u s a n g e t , Sweden (Hessland, 1949). P r i m i t i e l l a b r e v i s u l c a t a Hessland. R i g h t valve, x23, e a r l y Ordovician, Leskusanget, Sweden, (Hessland, 1949). Protallinella grewingki (Bock). R i g h t valve, x23, e a r l y Ordovic i a n , S t e n b e r g , Sweden (Hessland, 1949). Steusloffia a c u t a (Krause). L e f t valve, x15, e a r l y Ordovician? d r i f t boulders, Mark Brandenberg, G e r m a n y (Ulrich a n d Bassler, 1908). Steusloffia polynodulifera Hessland. L e f t valve, x23, e a r l y Ordovician, Born-Dadran, Sweden (Hessland, 1949).

23

Middle Ordovician The o s t r a c o d e s of t h e C h a z y a n (Llanvirnian a n d Llandeilan) of t h e e a s t e r n United S t a t e s a r e i e p r e s e n t e d by a lower Bullatella kauff manensis Zone and a n upper M o n o c e r a t e l l a t e r e s Zone= figs. 3-6, 21,) Swain 1957, 1962). Many o t h e r leperditiids, a p a r c h i t i d s , opikellids, leperditellids, eurychilinids, budnianellids a n d p r i m i t i v e cypridids a r e also r e p r e s e n t e d (Swain 1957, 1962) s o m e of which a r e listed in Table 2 a n d i l l u s t r a t e d in f i g u r e 3. An e x t e n s i v e silicified Chazyan f a u n a is r e p r e s e n t e d in Virginia ( K r a f t , 1962) a n d in New York (Swain, 1962). Black R i v e r a n (early C a r a d o c i a n ) o s t r a c o d e s a r e poorly known i n t h e e a s t e r n United S t a t e s a l t h o u g h w e l l r e p r e s e n t e d in t h e c e n t r a l United S t a t e s (Kay 1934, 1940; Swain, Cornell, a n d Hansen, 1961). Trentonian (middle C a r a d o c i a n ) shaly l i m e s t o n e s of New York a r e

24

Table 1. Early Ordovician Ostracoda, Atlantic Margins E, Eastern Atlantic; W , Western Atlantic Canadian Species Beyrichiona triceps Nanopsis nanella Primitia? sp. Aulacopsis spp. Conchoides minuta Glossomorphites tenuilimbata Primitiella brevisulcata PTotallinella grewingki Ceratocypris longispina Eurychilina dorsotuberculata Glossopsis depressolimbata Laccochilina dor soplica ta Ogmoopsis nodulifera Pinnatuli tes procer a Steuslof f ia cf. polynodulif e r a Beyrichia barrandiana Conchopr im i t ia eos C t e n t o m a plana Glossmor phi tes sp. Isochilina cris ta ta Isochilina gregar ia Isochilina seelyi Rigidella e r r a t i c a Steusloffia a c u t a Tetradella? sp. Isochilina a r c t i c a

* GB, G r e a t Britian; Gr , Greenland

N, Norway, S , Sweden; US, United States;

exemplified by Bassleratia typica Kay (Table 2, fig.2-31, Bollia subaeauata Ulrich (Table 2. fie. 3-41. Primitiella constricta Ulrich ( T a b l e g . 3-27), Thomasatia T a l c i c o k a (Table 2, f m d other forms (Kay 1934, 1940; Swain et a m In limestone facies of c e n t r a l and southern Sweden, t h e Llanvirnian (Aseri Stage) contains among others, Piretia geniculata Jaanusson (Table 2, fig. 3-23) and Laccochilina (L.) bulbata Jaanusson (Table 2, fig. 3-19). The overlying early Llandeilzn (=ae Stage) is typified by Eu rimites effusus Jaanusson (Table 2, fig. 2-12) and Actinochilina (Jaanusson,l957). The succeeding Uhaku S t a g e spp. Table 2, 1)3-

+-

25

Table 2. Middle Ordovician Ostracoda of Atlantic Margins E, Eastern Atlantic; W , Western Atlantic Mohawkian Chazyan Species LOC. Llanv. Lland. Bullatella kauffmanensis US --W-Laccochilina bulbata S --E-S -- E-Piretia geniculata Budnianella shenandoense US -------W Elliptocyprites parallela US -------W Eogra p hiodac t ylus eos us -------W Eurychilina strasburgensis US -------W Krausella variata us -----__W--? Primitiella champlainensis US -------W Actinochilina spp. Balticella spp. Conchopr imites? spp. Euprimites effusus Eupr imi tes bur sell us Euprimites suecicus Hesperidella spp. Parapyxion spp. Primitiella spp. Pyxion sp. Sigmobolbina sigmoidea Steusloffia linnarssoni Tallinella dimorpha Tvarenella spp. Ulrichia? bipunctata Monoceratella t e r e s Euprimites locknensis Plstybolbina spp. Steusloffia c o s t a t a Tetradella complicata Tallinella trident Ullerella triplicata Ctenobolbina spp. Bolbina spp.

.

Tr B.R. Early Caradoc.

26

contains, among others Laccochilina (L.) auci ranosa Jaanusson (Table 2, fig. 3-20), Euprimites bursellus Jaanusson Table 2 , fig. 3-13), Tallinella dimor ha Jaanusson (-fig. 3-32), Steusloffia linnars- Jaanusson Table 2, fig. 3-31), and soni Jaanusson (Table 2, fig. 3-29). In t h e l a t e t w o facies assemblages occur: a carbonate facies, with species of (Table 2, fig. 3-36), Euprimites 2, fig. 3-17) and Balticella a mudstone f a c i e s with Conchoprimites? (Table 2, fig. 3-71, Actinochilina (Table 2, fig. 3-1) and Parapyxion (Table 2); both f a c i e s a r e represented by Euprimites locknensis Jaanusson (Table 2, fig. 3-14), and Steusloff i a costata Jaanusson (Table 2, fig. 3-20) (Jaanusson 1957). A large middle Ordovician fauna is present in t h e Kuckruse and other formations of Estonia (Bonnema, 1909; Sarv, 1959).

E_B__

-+

Figure 3 1. 2. 3.

4. 5. 6. 7. 8.

9. 10. 11.

12.

Actinochilina suecica (Thorslund). Right valve of holotype, x19, middle Ordovician, Ludibundus beds, Kinnekulle, Sweden (Jaanusson, 1957). Balticella deckeri (Harris). Right valve, x13, middle Ordovician, Strasburg Junction, Virginia (Kraf t, 1962). L e f t valve, holotype, x23, middle Bassleratia typa Kay. Ordovician, Northumberland County, Ontario (Kay, 1934). Bollia subae u a t a Ulrich. L e f t valve, x23, middle Ordovician, Church, Iowa Kay, 1940). Budnianella shenadoense Kraf t. Right valve, holotype, x20, middle Ordovician, Tumbling Run, Virginia (Kraf t, 1940). Bullatella kauff manensis (Swain). Right valve, x16, middle Ordovician, Marion, Pennsylvania (Swain, 1957). Conchoprimitia leperditioidea Thorslund. Right valve, x15, middle Ordovician, Siljan, Sweden (Jaanusson, 1957). Ctenobolbina minor kuckersiana (Bonnema). L e f t valve, xll, middle Ordovician, early Caradocian, Kukruse, Estonia (Bonnema, 1909). Ctenbolbina o r n a t a latimarginata (Bonnema). L e f t valve, xll, middle Ordovician, early Caradocian, Kukruse, Estonia (Bonnema, 1909). Elliptocyprites longula Swain. Right valve, holotype, x36, middle Ordovician, Lake Champlain, Vermont (Swain, 1962). Eographiodactylus eos K r a f t . Left valve, x26, middle Ordovician, Tumbling R u n T r g i n i a (Kraft, 1962). Euprimites efiusus Jaanusson. a, L e f t valve, of heteromorph, x19, b, l e f t valve of heteromorph, middle Ordovician, Oland Seby, Sweden (Jaanusson, 1957.)

-*

27

13.

14. 15. 16.

17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29. 30.

31. 32.

Euprimites bursellus Jaanusson. L e f t v a l v e of h e t e r o m o r p h , x19, middle Ordovician, O s t e r g o t l a n d , Sweden (Jaanusson, 1957.) Euprimites locknensis (Thorslund). R i g h t v a l v e of h e t e r o m o r p h , x19, middle Ordovician, J a m tland, S w e d e n (Jaanusson, 1957). Euprimites s u e c i c u s (Thorslund). L e f t valve, of h e t e r o m o r p h , x19, middle Ordovician, J a m t l a n d , Sweden (Jaanusson, 1957). Eur‘ychilina s t r a s b u r g e n s i s K r a f t . L e f t v a l v e of f e m a l e , x13, middle Ordovician, S t r a s b u r g J u n c t i o n , Virginia ( K r a f t , 1962). Hesperidella e s t h o n i c a (Bonnema). R i g h t v a l v e of h e t e r o m o r p h , x28, middle Ordovician, Ludibundus L i m e s t o n e , T v a r e n a r e a , Sweden (Jaanusson, 1957). Krausella v a r i a t a K r a f t . R i g h t valve, x13, middle Ordovician, Strasburg J u n c t i o n , Virginia ( K r a f t , 1962). L a c c o c h a i n a ( L a c c o c h a i n a ) b u l b a t a Jaanusson. L e f t valve of tecnomorph, x19, middle Ordovician, O s t e r g o t l a n d , Sweden (Jaanusson, 1957). Laccochilina (Laccochilina) paucigranosa Jaanusson. L e f t v a l v e of h e t e r o m o r p h , x19, middle Ordovician, e r r a t i c boulder Erken No. 10, S o u t h Bothnia, Sweden (Jaanusson, 1957.) Monoceratella t e r e s T e i c h e r t . L e f t valve, x13, middle Ordovician, S t r a s b u r g J u n c t i o n , Virginia ( K r a f t , 1962). Parapyxion s i b o v a t u m (ThGslund). L e f t valve, x23, middle Ordovician Ludibundus beds, Vasterogotland, Sweden (Jaanusson, 1957). P i r e t i a g e n i c u l a t a Jaanusson. L e f t valve of h e t e r o m o r p h , x26, middle Ordovician, O s t e r g o t l a n d , Sweden (Jaanusson, 1957). P r i m i t i a s i m p l e x (Jones): R i g h t valve, x6, middle Ordovician, n e a r Coimbra. P o r t u g a l (Jones, 1855). P r i m i t i a ? bicornis (:ones). L e f t valve, x6, middle Ordovician, Shropshire, England (Jones, 1855). P r i m i t i e l l a c t a m p l a i n e n s i s Swain. R i g h t valve, x16, middle Ordovician, L a k e C h a m d a i n , V e r m o n t (Swain, 1962). Prirnitiella’ c o n s t r i c t a Ulrich. L e f t valve, x23, middle Ordovician, Cannon Falls, Minnesota (Kay, 1940). Pyxion c a r i n a t u m -(Hadding). R i g h t valve, x19, middle Ordovician, Scania, Sweden (Jaanusson, 1957). Sigmobolbina s i g m o i d e a Jaanusson. a, L e f t v a l v e of t e c n o m o r p h , x19; b, d i a g r a m m a t i c d r a w i n g of h e t e r o m o r p h of s p e c i e s , x30, middle Ordovician, Oland, Sweden (Jaanusson, 1957). R i g h t valve, xll, middle Steusloffia costata (Linnarsson). Ordovician, Ludibundus l i m e s t o n e , Siljan d i s t r i c t , Sweden (Jaanusson, 1957). Steusloffia- linnarsoni (Krause). L e f t valve, xll, middle Ordovician, Oland,-(Jaanusson, 1957). Tallinella d i m o r p h a Opik. R i g h t valve, xll, middle Ordovician, Siljan d i s t r i c t , Sweden (Jaanusson, 1957).

29

36

37

38

39

A f e w middle Ordovician ostracodes of primitiid and tetradellid types a r e known from France, Spain, and Portugal (Bassler and Kellett 1934). A g r e a t many species have also been described from drift boulders presumed t o be middle Ordovician in northern Germany (Kummerow, 1921). Ostracoda a r e s c a r c e in t h e United Kingdom prior to t h e Caradocian. Primitiids and tetradellids a r e common in t h e Caradocian and Ashgillian of Wales (Jones, 1855; Harper, 1947; A.W.A. Rushton, written communication, 6 February 1976). L a t e Llandeilan and early Caradocian beds in San Juan Province, Argentina contain Ctenobolbina?, Parenthatia, Balticella, and Anisochilina, all of which are reminiscent of Scandinavian and middle Appalachian Assemblages (Baldis and Rossi d e Garcia 1972). Figure 3. (Continued) 33. Tallinella trident Henningsmoen. L e f t valve, x16, middle Ordovician, Sandsvaer, Norway (Henningsmoen, 1953). 34. Tetradella complicata Salter. Right valve, x9, middle Ordovician, early Llandeilan, Pembrokeshire, WaledHarper, 1947). 35. Thomasatia falcicosta Kay. Right valve, x23, middle Ordovician, Cannon Falls, Minnesota (Kay, 1940). 36. Tvarenella c a r i n a t a (Thorslund). Right valve of tecnomorph, x19, middle Ordovician, Sodermanland, Sweden (Jaanusson, 1957). 37. Uhakiella coelodesma Opik. Right valve of male, x15, middle Ordovician, early Caradocian, Purtsejogi River, Estonia. 38. Ullerella triplicata Henningsmoen. L e f t valve, x13, middle Ordovician, Ringerike, Norway (Henningsmoen, 1953). 39. Ulrichia bipunctata (Jones and Holl). - Right valve, XU, middle Ordovician, Llandeilan, Brecknockshire, Wales (Jones and Holl, 1869).

30

T a b l e 3. L a t e O r d o v i c i a n O s t r a c o d a of A t l a n t i c Margins E, E a s t e r n A t l a n t i c ; W , W e s t e r n A t l a n t i c Eden-Mays Species Ceratopsis chambersi Ctenobolbina c i l i a t a Tetradella aff. quadrilirata Aparachites maccoyi Macronotella spp. Pla tybol bina cf p l a n a Primitia s a n c t b a t r i c i i

.

Rich-Gam

LOC.

us us us

GB N N GB

L a t e Ordovician T h e r e a r e s p a r s e late Ordovician Edinian, Maysvillian, a n d Richmondian ( L a t e C a r a d o c i a n a n d Ashgillian) o s t r a c o d e f a u n a s in c l a s t i c l i t h o f a c i e s of t h e e a s t e r n U n i t e d s t a t e s (Butts, 1940). A f e w s p e c i e s a r e l i s t e d in T a b l e 3 a n d i l l u s t r a t e d in f i g u r e 4, b u t in g e n e r a l t h e s e f a u n a s a r e poorly known.

Figure 4

1. 2.

3. 4.

5. 6. 7.

8.

A p a r c h i t e s m a c c o y i i J o n e s a n d Holl. R i g h t valve, x8?. l a t e Ordovician, C a r a d o c i a n (Bala), C h a i r of Kildare, Ireland ( J o n e s a n d Holl 1868). C e r a t o p s i s c h a m b e r s i (Miller). L e f t valve, i n t e r n a l mold, x9, l a t e ? Ordovician, Martinsburg Shale, R o a n o k e C o u n t y , Virginia. (Butts, 1941). C t e n b o l b i n a c i l i a t a (Emmons). L e f t valve, i n t e r n a l mold, x9, l a t e ? (Ordovician, M a r t i n s b u r g Shale, R o a n o k e C o u n t y , Virginia. (Butts, 1941) M a c r o n o t e l l a cf. M. r a e l o n a (Steusloff). R i g h t valve, x8, l a g e 0r d o v i c i a n , Ask e r y N o r w ay Henn i ngs m oe n , 195 4 ) Platybolbina cf. P. e l o n ata (Krause). L e f t valve, XU, late Ordovician, Oslo, Norway Henningsmoen, 1954). Platybolbina cfi P. l a n a ( K r G s e ) . . L e f t valve, x15, late Ordovician, Oslo, N2rway Henningsmoen, 1954). P r i m i t i a s a n c t i p a t r i c i i J o n e s a n d Holl. R i g h t valve, x15, late Ordovician, C a r a d o c i a n (Bala), C h a i r of Kildare, Ireland. T e t r a d e l l a -sp. aff. T. q u a d r i l i r a t a (Hall a n d Whitfield). R i g h t valve, x9, l a t e ? Ordovician, M a r t i n s b u r g Shale, R o a n o k e C o u n t y , Virginia. (Butts, 1941).

e_Tg

-+5

.

31

A hiatus occurs between middle Ordovician and l a t e Ordovician ostracode faunas in Norway, t h e Tretaspis beds being nearly barren (Henningsmoen, 1954b). The overlying Dalmanitina beds (Ashgillian) contain a varied fauna cf. P. plana Krause (Table 3, fig. 4-61, P. (Ta3le 3, fig. 4-51, Macronotella spp. (TaEle Ashgillian deposits of t h e United Kingdom have yielded a dozen or more species including Aparchites (Salter) (Table 3, fig. 4-11 and Primitia sanctipatricii Salter fig. 4-7). The l a t e Ordovician of Estonian S.S.R. has a maior ostracode fauna (Sarv, 1959). Other regions bordering t h e Atlantic'have f e w or no recorded l a t e Ordovician ostracodes. Silurian The distribution of Silurian Ostracoda around t h e "ProtoAtlantic" Ocean plotted on t h e map for t h e Lower Devonian of Smith, Briden, and Drewery (1973) is shown in Figure 5. Early Llandoverian (Medinan) ostracodes a r e poorly developed in eastern United S t a t e s owing to unfavorable sandy facies but a f e w leperditiids occur, i.e. Leperditia cylindrica Hall (Bassler and Kellett, 1934). L a t e Llandoverian C -C beds (Clinton Group) of t h e Applachian region United S t a t e 3 ape abundantly supplied with ostracodes and have been divided into t h e following zygobolbid zones in

32

Figure 5. Map of Lower Devonian, S-pole stereographic projection, a f t e r Smith, Briden, and Drewery (1973), showing Silurian ostracode distribution about t h e "Protoatlantic" Ocean. Circles and dots show interpretations of south polar positions as determined from various places, with size of circle proportional to degree of uncertainty. t h e Rose Hill Shale and other Clinton equivalents. The succeeding Wenlockian beds (Rochester Shale) contain another zone, t h e Drepanellina clarki(Tab1e 4, fig. 6-11). Ludlovian beds (McKenzie and Wills Creek Formations) have abundant small kloedenellids such as: Dizygopleura acuminata Ulrich and Bassler (Table 4, fig. 6-10), Eukloedenella umbonata Ulrich and Bassler (Table 4, fig. 6-12), and Kloedenella scapha Ulrich and Bassler (Table 4, fig 6-15) PAdolian shaly limestones have large Kloedenia (Table 4, fig. 6-16), Pintopsis (Table 41, Welleria (Table 4, f i g m e l l e r i o p s i s (Table 4, fig 6-32), and Lophokloedenia (Table 4, fig. 6-18), which a r e indigenous to t h e American Appalachians at t h e species level but have a number of European affinities (Berdan 1962, 1970, 1971a; Martinsson 1970; Swartz and Whitmore, 1956).

33

Table 4a. E a r l y Silurian O s t r a c o d a of A t l a n t i c Margins E, E a s t e r n A t l a n t i c ; W , W e s t e r n A t l a n t i c

Species Leperdi t i a cylindr i c a Zygobolba e r e c t a Zygobolba a n t i c o s t i e n s i s Zygobolba d e c o r a Zygobolbina e m a c i a t a Mastigobolbina l a t a Zygosella post i c a Bonnemaia rudis Mastigobolbina t y p u s P a r a e c h m i n a spinosa Arcuaria sineclivula Beyrichia p a u c i t u b e r c u l a t a Craspedobol bina a r m a ta Neobeyrichia r e g n a n s Nodibeyrichia scissa Platybolbina? bulbosa Primitiella? p a r a l l e l a

LOC.

us us us us us us us us us us

B N? N? B? GB,B N? N?

Medinian Early Niagaran Llandover ian Early Late

--w-?-w-? ?-W-? ?-w-?

?-w-?

?-W-? ?-W-? ?-W-? ? - W? ?-W ? E - - - - - - -? ? _ - - - - - - - -E - - - - - - -? ?---------E------? ? _ - - - - - - - - E - - - - - - -? ? - - - - - - - - - E - - - - - - -? ? - - - - - - - - - E - - - - - - -? ? - - - - - - - - - E - - - - - - -?

_________

T a b l e 4b. Middle Silurian O s t r a c o d a of A t l a n t i c Margins E, E a s t e r n A t l a n t i c ; W, W e s t e r n A t l a n t i c

SDecies Apatobolbina p l a t y g a s t e r Beyrichia kloedeni Craspedobolbina v a r i o l a t a Drepanellina c 1a r k i Microcheilinella variolaris Be yr ic hia ringer ikensis Craspedobolbina p e r c u r r e n s Dizygopleura a c u m i n a t a Entomozoe? marstoniana Eukloedenella u m b o n a t a Hemsiella a n t e r o v e l a t a Hemsiella m a c c o y a n a Kloedenella s c a p h a Neobeyrichia n u t a n s Primitiopsis planif r o n s Signetopsis s e m i c i r c u l a r i s Macrypsilon s a l t e r i a n u m Welleria obliqua

LOC. N GB GB,N

us B N B

us GB us B GB

us

B N N GB

us

34

Table 4c. L a t e Silurian Ostracode of Atlantic Margins E, Eastern Atlantic; W , Western Atlantic Pridolian (Downtonian) Species LOC. Middle and L a t e Cayugan B ? _ - - -E _ - - - ? Am phitoxis cur va ta Frost iella groenvalliana US,GB,N Hemsiella aff. maccoyana US,B Kloedenia crassipunctata us Le perdi t ia scalar is us Londinia arisaigensis US,GB Londinia aff. arisaigensis 5,US Londinia kiesowi B Lophokloedenia manliensis us Macrypsilon aff. salterianum us Nodibe yr ichia tubercula ta B Pintopsis spp. US,B Richteria? sp. us Sleia equestris G B, B, US W eller ioDsis iersevensis us ~~

++ +*

In Norwav (Oslo region) t h e Llandoverian is represented by Be richia- (Eobi richia) sfi. (Table 4, figs. 6-4), Table 4, figs. 6-26 Primitiella? spp. (Table moen, 1 9 5 4 ~ ) . The Wenlockian contains f e w ostracodes, among t h e m A atobolbina platygaster Kummerow (Table 4, fig. 6-2) (Hennings.c)The Ludlovian contains abundant Primitio sis spp. (Table 4, fig. 6-28), Si net0 sis spp. (Table 4, and Neobeyrichia rin erikensis Henningsmoen) (Table 4, fig. 6-5) (HenningThe Ludlovian of northwestern Europe is generally smoen, 1954c characterized by "amphitoxidine" ostracodes: Londinia sp. (Table 4, fig. 6-21), Lo hoctenella spp. (Table 41, and S l e i a m b l e 4, fig. 6-30) fauna occurs in l a t e Wenlockian? and Ludlovian (Martinsson 1962 beds (Berdan, 1967, 1970, 1971; Martinsson, 1970). The l a t e r Ludlovian (Leintwardinian and Whitcliffian Stages) in northern England comprises zones based on Nodibeyrichia (Table 4, fig. 6-24), Neobe richia (Table 4, fig. 6-23), Cyptopholobus, Juviella, and Hemsiella Table 4, fig. 6-14] (Shaw, 1971). The succeeding D o w n t o w n i a n m a o7 l i a n ) is characterized by t h e kloedenid Frostiella groenvalliana Martinsson (Table 4, fig. 6-13) (Shaw, 1971). A similar fauna occurs in New York, Maine and Nova Scotia (Martinsson, 1970; Berdan, 1970, 1972).

6

_E_T--

-?-

An interesting undifferentiated Silurian ostracode assemblage characterized by entomids was long ago recorded from Sardinia (Canavari, 1899, 1900). The entomids a r e generally believed to b e pelagic ostracodes (Rozhdestvenskaja, 1971) and although t h e family is known from t h e Ordovician, t h e Sardinian Silurian entomids seem to represent one ot t h e earliest pelagic assemblages.

35

Elsewhere in t h e A t l a n t i c basin, e x c e p t in e a s t e r n C a n a d a which is discussed herein by Dr. Copeland, Silurian o s t r a c o d e s a r e only slightly known; a f e w f o r m s h a v e been described f r o m F r a n c e (Tromelin and Lebesconte 1876) and f r o m Brazil (Clarke, 1869) (Table

4). Figure 6 1.

2. 3.

4. 5. 6. 7.

8.

9. 10.

11.

12. 13. 14.

15. 16. 17.

Amphitoxis c u r v a t a Martinsson. L e f t valve, f e m a l e , x45, Pridolian, Snoder Gotland (Martinsson, 1962). Apatobolbina p l a t y g a s t e r (Kummerow). L e f t valve, xll, Wenlockian, Ringerike, Norway (Henningsmoen, 1954). Beyrichia (Beyrichia) cf. B. kloedeni M'Coy). L e f t valve, x23, Wen I ock i a n , S h ro p shi r e , E "21 a w t in sso n , 19 6 2). Beyrichia (Eobeyrichia) p a u c i t u b e r c u l a t a Henningsmoen. L e f t valve, x14, Llandoverian, Gunneklev, Norway (Henningsmoen, 1954). Beyrichia (Neobeyrichia) ringerikensis Henningsmoen. Left valve, x7, Ludlovian, Oslo, Norway (Henningsmoen, 1954). Bonnemaia rudis Ulrich and Bassler. Right valve, x6, Niagaran, Powell Mountain, Tennessee (Ulrich and Bassler, 1923). Craspedobolbina a r m a t a Heningsmoen. L e f t valve, xll, Llandoverian, Oslo, N o r w m e n n i n g s m o e n , 1950). Craspedobolbina (Mitrobeyrichia) percurrens M a r t insson. Left valve of f e m a l e , x30, Ludlovian, Follingbo, Sweden (Martinsson, 1962). Craspedobolbina (Mitrobeyrichia) v a r i o l a t a Martinsson. Left valve of f e m a l e , x30, Wenlockian, Djupvik, Sweden, (Martinsson, 1962). Dizygopleura a c u m i n a t a Ulrich a n d Bassler. L e f t valve, x12, l a t e Niagaran, Cumberland, Maryland. (Ulrich and Bassler, 1923). Drepanellina c l a r k e i Ulrich and Bassler. L e f t valve of m a l e , x9, Niagaran, Cumberland, Maryland. (Ulrich and Bassler, 1923). Eukleodenella u m b o n a t a Ulrich and Bassler. L e f t valve, e x f o l i a t e d posteriorly, xl2, l a t e Niagaran, Flintstone, Maryland, (Ulrich and Bassler, 1923). Frostiella groenviliiana Martinsson. L e f t valve of f e m a l e , x23, Downtonian-Pribolian, Scania, Sweden (Mart insson, 1962). Hemsiella maccoyana. (Jonesj. L e f t valve of h e t e r o m o r p h , x30, Ludlovian, Kirkby Moor Flags, England (Shaw, 1971). Kloedenella s c a p h a Ulrich - a n d Bassler. L e f t valve, xl5, L a t e Niagaran, G r e a t Cacapon, Maryland (Ulrich and Bassler, 1923). Kloedenia c r a s s i p u n c t a t a - S w a i t z a n d Whitmore. L e f t valve of f e m a l e , X15, Cayugan, Austin's Glen, New York (Swartz a n d Whitmore, 1956). Leperditia scalaris p r a e c e d e n s Ulrich a n d Bassler. L e f t valve,

36

Figure 6 (continued) 18.

19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29. 30. 31. 32. 33. 34. 35. 36. 37.

x5, Cayugan, Pinto, Maryland (Ulrich and Bassler, 1923). Lophokloedenia manliensis (Weller). L e f t valve of male, x15, Cayugan, Tristate, New York (Swartz and Whitmore, 1956). Mastigobolbina la t a (Hall). Right valve of male, x6, Niagaran, New Hartford, New York (Ulrich and Bassler, 1923). Mastigobolbina typus Ulrich and Bassler. Right valve of female, x5, Niagaran, Six Mile House, Maryland (Ulrich and Bassler, 1923). Londinia kiesowi (Krause). Right valve of female, x23, Pridolian, e r r a t i c boulder, c e n t r a l Baltic a r e a (Martinsson, 1962). Macrypsilon sa'lterianum (Jones). Right valve, x30, Ludlovian, Kirkby Moor Flags, England (Shaw, 1971). Neobeyrichia (NeobeGichia) nutans (Kiesow). L e f t valve of female, x23, Ludlovian, Ham marudden, Sweden (Mart insson, 1962). Nodibeyrichia scissa Martinsson. L e f t valve of female, x23, Llandoverian, Hulte, Sweden (Martinsson, 1962). Paraechmina- s inosa (Hall). L e f t valve, x15, Niagaran, Rochest e r . New York Ulrich and Bassler. 19231, Platybolbina? bulbosa Henningsm'oen. L e f t valve, xll, Llandoverian, Oslo, N a H e n n i n g s m o e n , 1954). Primitiella? cf. P. parallels Kummerow. L e f t valve, xll, Llandoverian, G u n n a l e v , Norway (Henningsmoen, 1954). Primitiopsis cf. P. lanifrons Jones. L e f t valve, xll, Ludlovian, Oslo region, Norway Henningsmoen, 1954). Si net0 sis semicircularis (Krause). Right valve, x17, Ringerike, Norway, Henningsmoen, 19 54). Sleia e uestris Martinsson. L e f t valve of female, x34, Pridolian, Sles, Gotland Martinsson, 1962). Welleria obliqua Ulrich and Bassler. Right valve of female, x9, Cayugan, Hancock, Maryland (Ulrich and Bassler, 1923). Welleriopsis jerseyensis (Weller). Holotype l e f t valve of male, x14, Cayugan, Nearpass Quarries, New Jersey (Swartz and Whitmore 1956). Zygobolba anticostiensis Ulrich and Bassler. Right valve of male, x6, Niagaran, Anticosti Island, Quebec (Ulrich and Bassler, 1923). Zygobolba decora (Billings). Right valve of female, x23, Niagaran, Anticosti Island, Quebec (Martinsson, 1962). Zygobolba e r e c t a Ulrich and Bassler. L e f t valve of male, x6, Niagaran, Cherrytown, Pennsylvania (Ulrich and Bassler, 1923). Zygobolbina e m a c i a t a Ulrich and Bassler. Right valve of female, x6, Niagaran, Cove Gap, Pennsylvania (Ulrich and Bassler, 1923). Zygosella postica Ulrich and Bassler. Right valve of male, x6, Niagaran, Cove Gap, Pennsylvania (Ulrich and Bassler, 1923).

+-

_g_qT_ -p-7

-+

38

Figure 6 (continued)

39

Summary and Conclusions Early Paleozoic ostracodes, a r e plentifully represented in t h e marginal northern Atlantic region, but a r e poorly known or generally sparse in O C C U ~r r e n c e in t h e southern Atlantic, where early Paleozoic rocks a r e restricted in distribution. Although ostracodes occur in small numbers in most of t h e marine facies of t h e north Atlantic margins, they a r e most abundant and biostratigraphically useful in t h e time-absorbent, slowly-deposited rock units and a r e sparse in thick clastics or massive carbonate units. Cambrian archaeocopids, although poorly known, appear to have limited biostratigraphic possibilities in t h e Atlantic region. Early Ordovician ostracodes a r e presently or potentially useful as assemblage zone faunas in t h e North Atlantic region, but differ in important respects on either side of t h e Atlantic probably owing to minimal transoceanic connections during t h a t Epoch. The middle Ordovician radiation of northwestern European ostracodes t h a t took place from Europe to t h e present western North Atlantic and in some instances to t h e southwestern Atlantic w a s a striking event and probably represents increasing proximity of not only trans-protoatlantic plates, but connections with Gondwanaland as well. In l a t e Ordovician t i m e unfavorable epicontinental facies obscured ostracode faunal interrelationships but t h e y apparently remained similar in t h e North Atlantic area. The hindrance posed by unfavorable facies to knowledge of ostracode faunas continued through t h e early Silurian, but in t h e l a t e Llandoverian and Wenlockian well developed ostracode zones appeared in both t h e eastern United S t a t e s and p a r t of western Europe. The Ludlovian faunas on t h e other hand a r e not well matched in t h e United States and western Europe, perhaps owing to arid-facies controls. The Pridolian-Downtonian Age marks a return t o trans-protoatlantic similarities of ostracodes in t h e United S t a t e s and western Europe.

40

References Cited Baldis, Bruno and Rossi d e Garcia, Elsa, 1972, Algunos ostracodes der Llandeiliense - Caradociense d e la Republica Argentina. Revista Espanola de Micropaleontologia, v. 4, no. 1, p. 19-22. Barrande, Joachim, 1872, Systeme Silurien du c e n t r e d e la Bohkme. Ire partie. Recherches pal6ontologiques. Supplement a u vol. I, Trilobites. Crustaces divers et Poissons. Plates in s e p a r a t e atlas. Prague and Paris, (fide -Bassler and Kellett, 1934). Bassler, R. S., and Kellett, Betty, 1934, Bibliographic Index of Paleozoic Ostracoda. Geol. SOC. Amer. Spec. Paper 1, 500 p. Berdan, J. M., 1967, Baltic ostracodes from Maine. (in) Geol. Survey Research, 1966. U.S. Geol. Survey Prof. Paper 550-A, p. A l l l . , 1970, American ostracode zonation: in Correlation of t h e North American Silurian rocks. Geol. SOC. Arne,: Spec. Paper, No. 102, p. 39-40, 1970. , 1971, Some ostracodes from t h e Schoharie formation (lower Devonian) of New York. in Paleozoic perspectives; a paleontological t r i b u t e to G. Arthur-Cooper, Smithson. Contrib. Paleobiol., No. 3, p. 161-174, illus., 1971. , 1972, Brachiopoda and Ostracoda of t h e Cobleskill Limestone (Upper Silurian) of Central New York. U.S. Geol. Surv., Prof. Paper, No. 730, 44 p., illus. (incl. sketch map), 1972. Bonnema, J. H., 1909, Beitrag zur Kenntnis der Ostrakoden der Kuckersschen Schicht (C2). Mitt. Min. Geol. Inst. Univ. Groningen, vol. 2, pt. 1, p. 1-84, pls. 1-8. Leipzig and Groningen. Butts, C., 1940, Geology of t h e Appalachian Valley in Virginia. Geol. Survey Bull. 52, p. 333-335. Canavari, M., 1899, Ostracodi Siluriani di Sardegna. SOC. Toscana Sci. Nat. Pisa., Pr. Verb., v. 11, 1899, art. 5 , p. 150-153. , 1900, Fauna dei calcari nerastri con Cardiola ed Orthoceras di Xea San Antonia in Sardegna I. Palaeont. ital., 1899, v. 5 , p. 187-210, 2 tav. Pisa. Clarke, J. M., 1899, The Paleozoic faunas of Para, Brazil, I. The Silurian fauna of t h e Rio Trombetas. 11. The Devonian Mollusca of t h e s t a t e of Para. Mus. Nac. Rio d e Janeiro, Arch. v. 10 (author's English edition), p. 1-100, pls. 1-8, 1900, Albany. Cobbold, E. S., 1936, The Conchostracea of t h e Cambrian a r e a of Comley, Shropshire with a note on a new variety of Atops reticulatus (Walcott). Geol. SOC. London, Q. J. no. 367, v. 92, pt. 3, p. 221-235, 2 PIS. , and Pocock, R. W., 1934, The Cambrian a r e a of Rushton (Shropshire). Roy. SOC. London. Philos. Tr. B501, v. 223, p. 305-409. Gurich, George, 1896, Das Palaeozoicum im Polnischen Mittel gebirges. Russ. Kais. Min. Ges., St. Petersburg, Verh., ser. 2, v. 32, p. 374-392, pl. 10, fig. 15, pl. 14, pl. 15 (part).

41

Harper, J. C., 1940, The upper Valentian ostracode f a u n a of Shropshire. Ann. Mag. Nat. Hist., v. 11, p. 385-400. , 1947, Tetradella complicata (Salter) and some Caradoc species of t h e genus. Geol. Mag., v. 84, p. 345-353, pl. 10. Henningsmoen, Gunnar, 1953a, Classification of Paleozoic straighthinged ostracods. Norsk Geol. Tidsskrift, v. 31, p. 185-288, 12 t e x t figs. , 1953b, The Middle Ordovician of t h e Oslo region, Norway, 4. Ostracoda. Norsk Geol. Tidsskrift, v. 32, p. 35-56, 5 pls., 1 t e x t fig. , 1954a, Lower Ordovician Ostracoda from t h e Oslo region, Norway. Norsk. Geol. Tidsskrift, v. 33, nos. 1, 2, p. 41-68, 2 pls. , 195433, Upper Ordovician ostracods from t h e Oslo region, Norway. Norsk Geol. Tidsskrift, v. 33, nos. 1, 2, p. 69-108, pls. 1-6. , 1954c, Silurian ostracods from t h e Oslo region, Norway. 1. Beyrichiacea with a revision of t h e Beyrichiidae. Norsk. Geol. Tidsskrift, v. 34, no. 1, p. 15-71, 8 pls., 5 t e x t figs. Hessland, Ivar, 1949, Investigations of t h e Lower Ordovician of t h e Siljan District, Sweden. Bull. Geol. Inst. Uppsala, v. 33, 408 p., 26 pls. Jaanusson, Valdar, 1957, Middle Ordovician ostracodes of c e n t r a l and southern Sweden. Bull. Geol. Inst. Uppsala University, v. 37, p. 176442, 15 pls. Jones, T. R., 1855, Notes on t h e Paleozoic bivalved Entomostraca, No. 1, Some species of Beyrichia of t h e upper Silurian limestones of Scandinavia. Ann. Mag. N a t . Hist. Ser. 2, v. 16, p. 31-92, pl. 5. , 1856, Notes on t h e Paleozoic bivalved Entomostraca, No. 3, Some species of Leperditia. Ann. Mag. N a t . Hist., ser. 2, v. 17, p. 81-101, pis. 6, 7. , 1884, Notes on t h e Palaeozoic bivalved Entomostraca, No. 17, Some North American Leperditiae and allied forms. Ann. Mag. Nat. Hist. Ser. 5, v. 14, p. 339-347. , and Holl, H. B., 1869, Notes on Palaeozoic bivalved Entomostraca, No. 9, Some Silurian species. Ann. Mag. Nat. Hist., ser. 4, vol. 3, p. 211-227, pls. 14, 15. Kay, G. M., 1934, Mohawkian Ostracoda: species common to Trenton faunules from t h e Hull and Decorah Formations. Jour. Paleontology, V. 8, p. 328-343, PIS. 44-46. , 1940, Ordovician Mohawkian Ostracoda: lower Trenton Decorah fauna. Jour. Paleontology, v. 14, p. 234-269, pls. 29-34. Kraft, J. C., 1962, Morphologic and systematic relationships of some middle Ordovician Ostracoda. Geol. SOC. Amer. Mem. 86, 104 p., 19 pl., 15 t e x t figs. Krause, Aurel, 189 1, Beitrag zur Kenntniss der Ostrakoden-Fauna in Silurian Diluvialgeschieben. Deutsch. Geol. Ges., Zeitschr., v. 43, p. 488-521, PIS. 29-33.

42

Kummerow, E., 1924, Beitrage zur Kenntnis der Ostracoden und Phyllocar iden aus nordischen Diluvialgeschieben. Preuss. Geol. Landes., Jahrb., 1923, vol. 44, p. 405-433, pls. 21,22. Lundin, Robert F., 197 1, Possible paleoecological significance of Silurian and early Devonian ostracode faunas from midcontinental and northeastern North America (with discussion): (in) Oertli, H. J., ed., Paleoecology of ostracodes, Cent. Rech. Pau, Bull., vol. 5 , (suppl.), p. 853-868. Martinsson, Anders, 1962, Ostracods of t h e Family Beyrichiidae f r o m t h e Silurian of Gotland. Bull. Geol. Inst. Univ. Uppsala, v. 41, p. 1369, 203 text-figs. , 1970, Correlation with Europe: (in) Correlation of t h e North American Silurian rocks, Geol. SOC. Amer., Spec. Paper, No. 102, p. 41-44, 1970. Poulsen, C., 1929, The Cambrian, Ozarkian, and Canadian faunas of northwest Greenland, Medd. om Gronland, v. 70 (Jubilaeumsekpeditionen Nord om Gronland 1920-23, no. 21, p. 308316, pl. 21. , 1934, The Silurian faunas of North Greenland. 1. The f a u n a of t h e Cape Schuchert Formation. Medd. om Gronland, v.72, (Jubilaeumsekpeditionen Nord O m Gronland, 1920-23) p. 1-46, pl. 1-3. Rozhdestvenskaja, A. A., 197 I , Ostracods and paleogeographic conditions of their distribution in a l a t e Devonian basin in t h e east of t h e Russian Platform. (in) Oertli, H. J., ed., Paleoecologie Ostracodes, Bull. C e n t r e Rech. Pau. - SNPA, v. 5, suppl., p. 763-768. Sarv, L., 1959, Ordovician ostracods in t h e Estonia SSR. Eesti Nsvteaduste Akademmia Geoloogia Instidundi Unrimused, v. 4, 206 p., 32 pls. Shaw, R. W. L., 1971, Ostracoda from t h e Underbarrow, Kirkby Moor and Scout Hill Flags (Silurian) near Kendal, West morland. Palaeontology, vol. 14, pa$ 4, p. 595-611, illus., 1971. Smith. A. G.. Briden, J. C., and Drewery, G. E., 1963, Phanerozoic worid maps. Palaeontol. Assoc. Spec. Paper. 12;~. 1-42. Swain, F. M., 1953, Ostracoda from t h e Camden C h e r t , western Tennessee. Jour. Paleontology, v. 27, p. 237-284, pls. 37-39, 21 t e x t figs. , 1957, Early Middle Ordovician Ostracoda of t h e e a s t e r n Stratigraphic d a t a and description of United States, Part I. Leperditiidae, Aparchitidae, and Leperditellidae. Jour. Paleontology, V. 31, p. 528, 590, pis. 59-62. , 1962, Early Middle Ordovician Ostracoda of t h e e a s t e r n United States, P a r t 11. , Cornell, J. and Hansen, D., 1961, Ostracoda of t h e Decorah Shale of Minnesota. Jour. Paleontology, v. 45, p. 519-545. 1933, Dimorphism and orientation in ostracods of t h e Swartz, F. M., Family Kloedenellidae from t h e Silurian of Pennsylvania. Jour. Paleontology, v. 7, p. 231-260, pls. 28-30.

43

, 1939, Keyser Limestone and Helderberg Group, (in) B. Willard et al., The Devonian of Pennsylvania, Penn. Geol. Survey 4th Ser. Bull. G 19, p. 29-72. , and Whitmore, F. C., Jr., 1956, Ostracoda of t h e Silurian Decker and Manlius limestones in New Jersey, and e a s t e r n New York. Jour. Paleontology, v. 30, p. 1029-1091, pls. 103-110, 3 t e x t figs. Tromelin, G. and Lebesconte, P., 1876, Essai d'un catalogue raisonne des fossiles Siluriens des Departments d e Maine-et-Loire, d e l a Loire infe'rieure et du Morbihan. Assoc. Francaise I'Avanc. Sci., C.R., 4th Session, 1875, p. 623, Paris. Tschigova (Chizhova), V. A., 197 1, Geographical distribution of ostracods in t h e European sea basin a t Famennian time: (in) Oertli, H. J., ed., Paleoecology of ostracodes, Cent. Rech. Pau, Bull., vol. 5, (suppl), p. 755-76 1. Ulrich, E.O.,1890, 1891, New and l i t t l e known American Paleozoic Ostracoda. Cincinnati SOC. Nat. Hist., Jour., v. 13, p. 104-137, (ISSO), p. 173-211, (1891), 8 pis. , and Bassler, R. S., 1908, New American Paleozoic Ostracoda. Preliminary revision of t h e Beyrichiidae, with descriptions of new genera. U.S. Nat. Mus., Pr., i. 35, p. 277-340, figs. i61, PIS. 37-44. , 1923, Maryland Geological Survey, Silurian volume, 794 p., 27 figs., 67 pls. Paleozoic Ostracoda: their morphology, classification and occurrence, p. 27 1-39 1. Systematic paleontology of Silurian deposits (Ostracoda) p. 500-704, pls. 36-65, Baltimore. , 1931, Cambrian bivalved C r u s t a c e a of t h e Order Conchostraca. U.S. Nat. Mus. Proc., v. 78, P a r t 4, p. 1-130, pl. 1-10.

44

Additional References Not Cited Abushik, A. F., 1967, The Importance of ostracods in drawing t h e Siluro-Devonian boundary in t h e European part of t h e USSR. (in) Oswald, D. H., ed., Internat. Sympos. on Devonian System, Calgary, Alberta, Alta. SOC. Pet. Geol., v. 2, p. 875-884. Brookins, Douglas G; Berdan, J e a n M.; and Stewart, David B., 1973, Isotopic and Paleontologic Evidence for correlating t h r e e volcanic sequences in t h e Maine coastal volcanic belt. Geol. SOC. Am., Bull., v. 84, no. 5, p. 1619-1628. Guber, A. L. and Jaanusson, Valdar, 1964, Ordovician ostracodes with posterior domiciliar dimorphism. Bull. Geol. Inst. Univ. Uppsala, v.42, no. 53, 43 p., 6 pls. Gurevich, K. Ya., 1971, (Silurian-Devonian boundary and S t a g e Subdivision of t h e Lower Devonian in t h e Lvov Paleozoic Depression): Meyhdunar. Simp. Granitsa Silura Devona, Biostratigr. Silura, Nizhega Srednego Devona, Tr., no. 3, v. I, p. 79-85. Krandievsky, V. S., 1963, Fauna ostracod siluriiskikh vidkladiv Podillya, Akad. Nauk. Ukrain. RSR, Inst. Geol. Nauk, Kiev, 148 pp. , 1971, (The Silurian-Devonian Boundary of Volyn-Podolia based on Ostracods and Graptolites): Mezhdunar. Simp. Granitsa Silura Devona, Biostratigr. Silura, Nizhego Srednego Devona, Tr., no. 3, v. 1, p. 108-113, (inc. Engl. sum.). Le Fevre, J., 1967, (Succession of Ostracod and Conodont Associations in t h e Silurian Lower Devonian, and Eifelian from Several Sections in France and t h e Sahara). (in) Colloque sur l e devonien inferieur et ses limites (Rennes, 16-24 Septembre 19641, Fr., Bur. Rech. Geol. Minieres, mem., no. 33; p. 373-389. Martinsson, A., 1963, Kloedenia and related Ostracode genera in t h e Silurian and Devonian of t h e Baltic a r e a and Britain. Geol. Inst. Univ. Uppsala, Bull. 42, p. 1-63. , 1965a, The Siluro-Devonian ostracode genus Nodibeyrichia and faunally associated kloedeniinen. Geol Foren. Forhandl., v. 87, p. 109-138. , 1965b, Remarks on t h e Silurian ostracode genus Craspedobolbina from t h e Baltic a r e a and Britain. Geol. Foren. Stockholm, Forh. v. 87, pt. 3, no. 522, p. 314-325, illus., 1965. , 1967, The succession and correlation of ostracode faunas in t h e Silurian of Gotland. Geol. Foren. Forhandl., v. 89, p. 350-386. , 1968a, An Appalachian species of t h e Silurian Ostracode Genus Craspedobolbina. Geol. Foren. Stockholm, Forh., v. 90, pt. 2, no. 633, p. 302-208, illus., 1968. , 1968c, The Appalachian species of t h e Silurian Ostracode Genus Craspedobolbina. Geol. Foren. Forhand, Stockholm, v. 90, p. 302-308, 6 text-figs.

45

Petersen, L. E.; and Lundin, R. F.., 1974, Thlipsura martinssoni, a new ostracode species from t h e Silurian of England. J. Paleontol., v. 48, no. 2, p. 357-360. Pranskevichus, A. A., 1970, Silurian ostracod assemblages of t h e south Baltic Region and their correlation value: Acad, Sci. USSR, Dokl., Earth Sci. Sect., vol. 192, p. 83-85. , 1971, (New ostracodes of Wenlockian a g e in t h e southern Baltic region): (in) Paleontologiya i stratigrafiya Pribaltiki i Belorussii, sbornik 111, p. 51-60 (incl. Engl. sum,), illus., Lit. NauchnoIssled. Geologorazc. Inst. Vilnius., 1971. , 1971, (Paleontological characteristics of lower Silurian in t h e southern Baltic region based on studies of Ostracods): (in) Paleontologiya i stratigrafiya Pribaltiki i Belorussii, shomik 111, p. 6170 Inst., Vilnius, 1971. , 1972, (Silurian ostracods of t h e southern Baltic sea): Liet. Geol. Mokslinio Tyrimo Inst., Tr,, no. 15, 180 p. (incl. Lith., Engl. sum.), illus. (Incl. sketch map), 1972. ,1972, (New Silurian rishonids f r o m t h e South Baltic area): (in) Novyye vidy drevnikh rasteniy i bespozvonochnykh SSSR, p. 272275, illus., Akad. Nau, SSSR, Nauch. Soviet Probl., Moscow, 1972. ,1972, (Silurian Ostracoda of t h e south Baltic region): Vilnius, Geol., Inst., Darb., no. 15, 280 p. (incl. Lith., Engl. sum.), illus. (incl. sketch map), 1972. , 1972, Ostracods from t h e Upper Silurian of t h e Southern Baltic region: Geol. Foeren. Stockh., Foerh., v. 94, p a r t 3, no. 550, p. 439-447, ilus., 1972. , 1972, New ostracods of t h e Llandoverian of Lithuania. Geol. Foren. Stockh., Foerh., v. 94, p a r t 3, no. 550, p. 435-438, illus., 1972. , 1973, New l a t e Silurian ostracodes from t h e South of t h e Baltic region: Paleontol. J., v. 7, no. 1, p. 32-42, illus., 1973. , 1973, (New l a t e Silurian ostracods from t h e South of t h e Baltic region): Paleontol. Zh., no. I, p. 39-47, illus., 1973. , 1973, New l a t e Silurian ostracodes from t h e south of t h e Baltic region): Paleontological Journal, v. 7, no. I, p. 32-41, pls. 3, 4. Robardet, M.; Henry, J. L.; Nion, J.; et al., 1972, (Pont d e Daer (Caradocian) Formation in t h e Domfront and Sees Synclines, Normandy): SOC. Geol. Nord., Ann., v. 92, no. 3, p. 117-137 (incl. Engl. sum), illus, 1972. Sarv, L., 1973, (Zonation of t h e Silurian in t h e section of t h e Kalvariya Well based on ostracods): Eesti NSVstead. Akad., Toim., Keemia Geol., v. 22, no. 2, p. 88-91, illus., 1973. Schallreuter, R U, 1967, (New ostracods f r o m Ordovician boulders). Geologie (Berlin), v. 16, no. 5, p. 615-631 (incl. Engl. Russ. sum.) illus., 1967.

46

, 1968, (Ordovician Podocopida; Beecherellidae). Neues Jahrb. Geol. Palaontol., Abh., v. 131, no. 1, p. 82-96 (incl. Engl. sum.), illus., 1968. , 1969, Neue Ostracoden aus ordovizischen Geschieben, 11. Sonderdruck aus Geol. Jg. 18, H.2, Akad-Verlag Berlin, p. 203-215, 3 PIS. , 1971, Ostrakoden aus Ojlemyrgeschrieben (Ordoviz) N. jb. GeoLPalaont, Mh, Jg. 1971, H. 7, p. 423-431, 1 pl. , 1971 (Asymmetric Ordovician Ostracods): Neues Jahrb. Geol. Palaeontol., Monatsh, no. 4, p. 249-260 (incl. Engl. sum.), illus., 1971. ,1971, (Ostracods from t h e Ojlemyr flint, Ordovician): Neues Jahrb. Geol. Palaeontol., Monatsh, no. 4, p. 423-431 (incl. Engl. sum.), illus., 1971. , 1972, (Drepanellacea (Ostracoda, Beyrichicopida) f r o m t h e middle Ordovician Backstein Limestone boulders: 4, L a t e r o hores hystrix n. sp., Pedomphalella germanica n. sp. and Easc midtella fragosa): Dtsch. Ges. Geol. Wiss., Ber., Reihe A. Geol. Palaontol., v. 17, no. I, p. 139-145, illus., 1972. Shaw, R. W. L., 1971, The faunal stratigraphy of t h e Kirky Moor f l a g s of t h e type a r e a near Kendal, Westmorland: Geol. J., v. 7, p a r t 2 , p. 359-380, illus. (incl. geol. m a p 1:63, 3601, 1971. Sidaravichene, N.V., 1971, (New Ostracods from t h e middle and upper Ordovician of Lithuania), (in) Paleontologiya i stratigrafiya Pribaltiki i Belorusii, sbornik 111, p. 23-36 (incl. Engl. sum.), illus. (incl. sketch map), Lit. Naerchno-Issled. Geologorazv. Inst., Vilnius, 1971. Whitfield, R. P.! 1890, Observations on some imperfectly known fossils from t h e calciferous sandrock of Lake Champlain and descriptions of several new forms. Am. Mus. N a t Hist. Bull. 2, 56-80., pl. 13, figs. I6. Zbikowska, B., 1973, (Upper Silurian Ostracods from t h e Leba Elevation, northern Poland): (in) P r a c e zwiazane y problematylca struktur wg lebnych Polski, A c t a Geol. Pol., v. 23, no. 4, p. 607-644, (incl. Engl. sum.), illus., 1973. Zenger, D. H., 1971, Uppermost Clinton (Middle Silurian) Stratigraphy and Petrology, East-Central New York: N.Y. State Mus. Sci. Serv., Bull., no. 417, 58 p. illus. (incl. sketch map), 1971.

+

47

Discussion S . Bergstr8m: I w a s most i n t e r e s t e d t o l e a r n a b o u t t h e B a l t i c a f f i n i t i e s of t h e o s t r a c o d e s of t h e San J u a n F o r m a t i o n o f A r g e n t i n a , a n d r e f e r -

Dr.

ence t o i t a s b e i n g o f L l a n v i r n i a n a n d L l a n d e i l a n a g e . The c o n o d o n t f a u n a o f t h i s u n i t a l s o shows B a l t i c a f f i n i t i e s b u t , a s n o t e d by S e r p a g l i (1974), i t s u g g e s t s a l a t e A r e n i g i a n r a t h e r t h a n y o u n g e r a g e o f t h e f o r m a t i o n . Can t h e S a n J u a n o s t r a c o d e s be u s e d t o d a t e t h e f o r m a t i o n , and i f s o , d o t h e y show c o r r e l a t i o n w i t h L l a n v i r n i a n and L l a n d e i l a n s t r a t a i n n o r t h w e s t e r n E u r o p e r a t h e r than with Arenigian u n i t s ? Swain: The few s p e c i e s o f o s t r a c o d e s from t h e S a n Juan Formation are n o t d e f i n i t i v e i n a g e , b u t a r e more s u g g e s t i v e o f m i d d l e t h a n o f e a r l y Ordo v i c i a n . Reconstructions of c o n t i n e n t a l p o s i t i o n i n t h e O r d o v i c i a n by S m i t h e t a 1 . ( 1 9 6 3 ) s h o w t h a t s h a l l o w m a r i n e m i g r a t i o n s b e t w e e n t h e B a l t i c area and w e s t e r n S o u t h America c o u l d r e a s o n a b l y h a v e occurred. D r . M . C . Keen: I n y o u r a b s t r a c t you m e n t i o n e d b r a c k i s h water o s t r a c o d s i n t h e L u d l o v i a n . When d i d b r a c k i s h water o s t r a c o d s f i r s t a p p e a r ? How d o you r e c o g n i s e them and a r e t h e r e a n y f r e s h - w a t e r ones? Swain: J e a n B e r d a n and I h a v e d i s c u s s e d t h i s s e v e r a l times. C e r t a i n e l o n g a t e , s u l c a t e (eukloedene l l i d o s t r a c o d e s o f t h e S i l u r i a n may r e p r e s e n t e i t h e r b r a c k i s h o r h i g h - s a l i n i t y forms; t h e y occu r i n f o s s i l i f e r o u s r e d b e d s (Bloomsburg) a s d e s c r i b e d by H o s k i n s from c e n t r a l P e n n s y l v a n i a . D r . J . Berdan: I would a g r e e w i t h t h a t , a n d a l s o I think t h a t the difference i n t h i s context, b e t w e e n t h e A p p a l a c h i a n f a u n a , d o m i n a t e d by k l o e d e n e l l i d s , and t h a t t o t h e w e s t , s u c h a s t h e Henr y h o u s e Formation where k l o e d e n e l l i d s a r e n o t abu n d a n t , i n d i c a t e s t h a t t h e r e w a s something p e c u l i a r about t h e environment i n t h e Appalachian area a t t h a t t i m e . Swain: One o f t h e p r o b l e m s i s t h a t t h i s w a s a t i m e d u r i n g which e v a p o r f t e c o n d i t i o n s o c c u r r e d i n t h e A p p a l a c h i a n r e g i o n , so i t i s d i f f i c u l t t o know w h e t h e r t h e s e a r e h i g h o r low s a l i n i t y f o r ms. A s f a r as f r e s h w a t e r forms are concerned, w e have i n d i c a t i o n s of f r e s h w a t e r s p e c i e s i n t h e C a r b o n i f e r o u s and p e r h a p s i n t h e Devonian.

--

48

Berdan: I think they are earlier and appear in the middle or late Silurian. Murray Copeland has more information. Dr. J. E. Conkin: Does the Pridolian represent a pulsation (transgression) of the seas onto the continents? If so what is the bearing of this on the Silurian-Devonian boundary? Swain: The result of a late Silurian transgression in the Appalachians, as well as a return to a more favorable benthic environment seems to have been the production of a transitional Siluro-Devonian population of ostracodes and other invertebrates in such units a s the Keyser Limestone.

49

PALEOZOIC SMALLER FORAMINIFERA OF THE NORTH AMERICAN ATLANTIC BORDERLANDS by James E. Conkin, University of Louisville, Lou. Ky. 40208 and Barbara M. Conkin, Jefferson Community College, Lou. Ky. 40202 Abstract Species of Paleozoic smaller Foraminifera, combined . with physical evidence of diastrophism (paracontinuity), may be used in precise placement of time-stratigraphic boundaries in the eastern United States as with the Devonian-Mississippian and KinderhookianOsagean boundaries. Evolutionary lineages a r e recognized in t h e Devonian and Mississippian and certain stratigraphic intervals within the Lower and Middle Paleozoic are delimited by foraminifera1 zones; nevertheless, even though the stratigraphic value of Paleozoic smaller Foraminifera has been demonstrated, their full potential remains to be realized. Agglutinated Foraminifera frequently occur in shale and limestone containing silt or fine sand; however, their distribution varies in diverse lithologies within single genetic units. Sparry bioclastfc calcarenites rarely contain agglutinated Foraminifera, but often bear calcareous forms. Earliest textulariinid Foraminifera, consisting of simple, free or attached, tubular, globular, spherical, or hemispherical chambers, arose by mid-Ordovician. Tubular t o hemitubular attached forms appeared in late Ordovician. Apertured planoconvex, tubular, irregularly coiled and planispirally coiled forms and globular forms with various projections, arose in early Silurian. Multichambered Highly forms with enlarging chambers began in late Devonian. organized, attached hemitubular, and well-organized multichambered forms, appeared in early Mississippian and evolved into more complex multichambered forms (including attached forms) in Pennsylvanian and Permian. Microgranular calcareous (fusulininid) foraminiferans arose in Middle Devonian and increased in number and complexity in Mississippian, Pennsylvanian, and Permian. Calcareous porcelaneous (miliolinid) tests appeared in early Pennsylvanian and calcareous hyaline (rotaliinid) tests evolved in early Permian.

50

\

Les esp\eces d e petits foraminiferes pale*ozoiques, unies 3 l a preuve physique du diastrophism (paracontinuit&), peuvent Ae t r e utilisdes dans l'emplacement pr6cis des frontikres d e temps-stratigraphiques dans l a rdgion est des Etats-Unis c o m m e a v e c l e s frontikres Les lignages d6vonien-mississippiens et kinderhookien-osagkens. 4volutionnistes se sont reconnus dans l e dkvoni/en et l e mississippien. Certains intervalles stratigraphiques dans l e paleozoique infdrieur et l e mi-palebzoique sont delimitds par d e s zones foraminif6rales; n6anmoins, malgre' la valeur stratigraphique dCyontre'e des petits foraminifkres pale'ozoiques, leur potentialit6 r e s t e a S t r e rCalise'e. Des foraminifkres agglutings souvent se trouvent dans d e s schistes argileux et d e s calcaires contenant d e s sables fins ou d e s vases. Cependant, leur distribution se varie dans d e diverses lithologies l'int6rieur d e simples unit& g6nCtiques. I1 est :are q u e les sparry calcarenites bioclastiques contiennent des foraminiferes agglutin6s mais souvent donnent des formes calcaires. Par l e mi-ordovicien, les plus anciens foraminif&es textulariinid apparaissaient. 11s contenaient des chambres, soit simples, soit libres ou lides, soit tubulaires, g!obulaires, sphgriques o u he'misph6riques. Des for mes lids tubulaires a l'hdmi-tubulaires apparaissaient pendant l'ordovicien r6cent. Des formes planoconvexes \ apertures, ainsi que tubulaires, lov& irre'gulikrement et loves planispiralement et d e s for mes globulaires projections diverses apparaissaint pendant l e d6but du silurien. Des f o r m e s multichambrks a v e c d e s chambres aggrandissantes commensaient pendant l e dgvonien re'cent. Des f o r m e s multichambrds l i i s , he'mitubulaires, assez complexes et organisds apparaissaient pendant l e d6but du mississippien et se sont Cvoluks e n des f o r m e s multichambr6s plus complexes (y compris l e s formes lids) pendant l e pennsylvanien et l e permien. Des foraminifkres microgranulaires calcaires (f usulininid) apparaissaient dans l e midevonien et se sont augment& e n nombre et complexitd pendant l e mississippien, le pennsylvanien et l e permien. Des tests calcaires porcelanaires (miliolinid) apparaissaient pendant l e d6but du pennsylvanien. Des tests calcaires hyalines (rotaliinid) se sont kvoluds pendant l e ddbut du permien.

>

51

Introduction Agglutinated and microgranular, porcelaneous, and hyaline calcareous (excluding fusulinid, endothyrid, and tournay ellid) foraminiferans may be considered %mailer" Foraminifera; however, even these may require sectioning for identification. Paleozoic smaller Foraminifera from the North American Atlantic borderlands (Texas to New York and Ontario), have been studied for nearly 50 years, but the quality of the work is uneven. Reviews of North American late Devonian-early Mississippian agglutinated Foraminifera (Conkin and Conkin, 1967 and 1970) and smaller Foraminif era of the pre-Pennsylvanian (Conkin and Conkin, 1973a) stressed their stratigraphic significance. Agglutinated Foraminifera occur abundantly in shale (Conkin, 1961, p. 234) which contains silt and/or fine-grained sand, as well as in limestone (even sublithographic) if fine-grained detrital material is present, but they may be unevenly distributed in diverse lithologies within a single genetic unit; limestone lenses and impure ironstone concretions may contain many specimens, while surrounding shales, silty shales or shaly siltstones bear essentially none. Sparry bioclastic calcarenites rarely contain agglutinated forms, but calcareous foraminiferans are frequently found therein. The dominance of agglutinated (textulariinid) Foraminifera in early Paleozoic resulted from their early evolution and pioneer occupation of shallow marine benthonic niches; with evolution in the Devonian of calcareous Foraminifera, competition ensued and increased significantly from Carboniferous onward, with calcareous groups progressively replacing agglutinated forms in "normal epicontinental" marine environments. Paleozoic Genera Of Smaller Foraminifera In preparing generic keys and ascertaining ranges of genera (Text-figs. 1-31, we have exercised our best judgment in determining the validity of records of stratigraphic occurrence and taxonomic assignment. The keys serve to clarify generic identities and relationships. We consider several genera recorded from the Paleozoic t o be junior synonyms (in parentheses) of the following: Calcitornella (ADterrinella. Calcivertella and Plummerinella), Hemisphaerammina (Fairliella; Metamorphina, and l T W e b b i n r n , A m movertella (Ammodiscella), Oryctoderma (Crithionina), Ordovicina (Croneisella, Gastroam mina, and Shidelerella), Nodosinella - Climacammina Mono enerina), Palaeotextularia (Paratextularia), &:ml Saccam mina (Proteonina, Raibosammina and T v Lunucam mina (Geinitzina), and Tholosina (Amphicervicis). Other genera are so ill understood '(Agathamminoides, Kerionammina, Tuberitina, Stacheia, and Stacheoides) that no useful statement can be made. Some genera have been recorded erroneously from the Paleozoic (Astrammina, Astrorhiza, Bullapora I and

52

ORDOVICIAN

SILURIAN

IARLY IMIDDLEI LATE

EARLY IliIDDLEI LATE

DEVONIAN EARLY lHIDDLE[ LATE

’-ASCHEMONELL

EUDOPALMULA

1

I

TEXT-FIGURE

1.

GENERIC RANGES OF PALEOZOIC SMALLER

53

IIISSISSIPPIAY EARLY

I MIDDLE^

LATE I

ORTHOVERTELLA

AMVOVERTELLA

PREPEILOPSIS PLACOPSILIIUA

F O W I N I F E R A IN THE NORTH AMERICAN ATLANTIC BORDERLANDS.

54

Schizammina); and still others have been incorrectly assigned t o the Foraminif era (Thuram minoides, a radiolarian, and Weikkoella, a charophyt e). Ranges And First Occurrences Of Some Genera Of Foraminifera Text-figure 2 presents the stratigraphic ranges of genera of Foraminifera in the Paleozoic of the North American Atlantic borderlands arranged systematically. Text-figure 3 presents t h e genera arranged according to their first occurrences (see Text-figure 1 for illustrations of genera). The agglutinated Foraminifera are represented by the suborder Textulariina, with two superfamilies, the Ammodiscacea (globular, tubular, or irregular tests with one or more apertures) and the Lituolacea (multilocular, rectilinear, enrolled or uncoiled, or trochospiral coil modified to biserial, tests). The suborder Fusulinina (with a nonlamellar, microgranular, calcite wall) is represented by two superfamilies, the Parathuramminacea (with globular or tubular tests with one or more apertures) and the Endothyracea (with multiple, rectilinear, enrolled, or biserial chambers and single to multiple apertures). The suborder Miliolina (with an imperforate, porcelaneous, calcite wall) is represented by the superfamily Miliolacea (comprising forms with a proloculus and tubular second chamber, planispirally or variously coiled) and the suborder Rotaliina (calcareous, hyaline, perforate, lamellar tests) is represented by the superfamily Spirillinacea. The first textulariinid Foraminif e r a had simple tests consisting of free or attached, tubular, globular, spherical, or hemispherical chambers; by Middle Ordovician, the tubular Bathysiphon, H perh e ammina, and Rhabdammina, the box-like planoconvex Hemisphaeram mina and tubular to hemitubular attached To1 pammina and the globular t er simple forms appeared Blastammina arose in late Ordovocian. in early Silurian: the globular Psammosphaera and Sorosphaera and planoconvex -Webbinelloidea, . as well as the tubular, irregularly coiled GlomospirE Lituotuba and the planispirally coiled Ammodiscus. Barly Sil- ' A globular forms with various projections are Saccammina, La enarrimina, Thurammina, and Pseudastrorhiza. The first multicham ere agg utinated forms with chambers enlarging in size a r e found in late Devonian: the attached multichambered Oxinoxis and the free

+

b

my-

TEXT-FIGURE

2.

GENERIC RANGES OF PALEOZOIC SMALLER FORAMINIFERA, ARRANGED ACCORDING TO

SYSTEMATIC CLASSIFICATION.

SOLID LINE INDICATES RECOROED OCCURRENCES; DOTTED LINE,INFERRED OCCURRENCES. ARROW INDICATES RANGE ABOVE PALEOZOIC. 55

TEXT-FIGURE

3. GENERIC RANGES OF PALEOZOIC SMALLER FORAMINIFERA &KANGED ACCORDING TO THEIR F I R S T OCCURRENCES.

56

Reophax (first abundant in early Mississippian). The attached, spiral, tubularTrepeilopsis is first found in late Devonian. The organized attached hemitubular form, Ammovertella, appeared in early Mississippian when the well-organized multichambered Trochammina and Ammobaculites also appeared. In early Pennsylvanian other complex agglutinated for m s appeared : Haplophrag m oides, Text ularia , Bigenerina, and Mooreinella. Finallv, in late Pennsylvanian, the Y attached, multichambered P1acopsilina"arose. The earliest known calcareous foraminiferan, the complex, multichambered Semitextularia, first appeared in Middle Devonian. Two simpler calcareous forms are the two-chambered (proloculus and tubular second chamber) rectilinear Earlandia and the planispiral Cornuspira which appear in middle Mississippian. More complex calcareous genera are found in late Mississippian: Palaeotextularia, Cli macam mina, and Tetra taxis. A number of new calcareous forms appeared in Early Pennsylvanian: Nodosinella, Polytaxis, Valvulinella, Globivalvulina, Brad h a , Aeathammina. Calcitornella. and SDirillina. Textularia. Hemiaor lus, a i d Rectocornuspira appeared in middlePennsylvanian, and, in late Pennsylvanian two additional multichambered genera, Glyphostomella and Lunucammina. Finallv. in earlv Permian, a comdex, multichambered rotaliinid calcarGous genus; Patellina,- was introduced.

-41

Zonation By Smaller Foraminifera And Devonian Early Mississippian Evolutionary Lineages

We restrict our zonation to the pre-Chesterian portion of the Paleozoic and include only those Foraminifera which a r e taxonomically valid, widely distributed, and occupy well-defined, rather short stratigraphic intervals. Text-figure 4 illustrates and presents notes on the recognized foraminifera1 zones as well as evolutionary lineages recognized by us in the Devonian-early Mississippian. Smaller Foraminifera And Time-Stratigraphic Boundaries Early Mississippian smaller Foraminif e r a are best known of any in the Paleozoic and a number of species have quite restricted ranges, and can be used for age determination, correlation, and boundary placement. Using agglutinated Foraminifera (Text-figure 5) as the biologic parameter and paracontinuities as the physical parameter, we have succeeded in precise placement of t h e long-sought DevonianMississippian boundary, as well as the Kinderhookian-Osagean boundary, in east-central United States (Conkin and Conkin, 1973b and 1975).

-

I

MI S S I S SI PPIAN

c

Oxinoxts Iigula,

Tolypommina bulbosa,

Tolypammina gersterensia,

Tolypommlna cyclops,

Tolypommina jacobschapelensis,

Hyperammino rockfordensis Ammodiscus longexssrtus,

Ammodiscus semiconstrictus,

Hyperommino coaleri Hyperommino compocto, Hyperommino yrocilenta,

I

Rcophnx lochryrnosus

I

Tolypommino bronsoni, Tolyparnminn friizelli, Ammoboculites lepfns,

Hyperommino conslricta,

Thurornmino ? iriradiota, Trepeilopsis glornospiroides, Ammovertella ltsoe,

Reophox calothus

Ammovertella p i k e i , Arnrnobaculites qutschicki, Trepeilopsis recurvidens hnmoboculites beveridgei, rrochommino mehli,

O r i n o r i s swollowi

Hyperammino nitido,

Sorosphoero ?cooperensis,

Trepeilopsis prodigalis,

Saccammino howei, Reophaa Reophax nor t hviewensis, Pseudostrorhizo

buccino,

Lituotu ba semiplana

conic0 , Pseudastrorhiza delicato

, Amrno-

boculites choppelensis, xmsphaero papilla, Thummmina congesta Pseudostrorhiro digitata, rhiza bocculo,

Pseudastrorhiza lonceola, Pseudmiro-

Tolypammina loocoon, Tolypomrnina botanuncus

Tolypammina r o t u l a Reophax %.A,

Thurornmino orenacorna

TEXT-FIGURE 4. FORAMINIFERAL ZONATION IN THE l.OWER PALEOZOIC AND EVOLUTIONARY LINEAGES IN THE DEVONIAN-LOWER MISSISSIPPIAN.

AND MIDOLE NORTH AMERICA.

References Cited Conkin, J. E., 1961. Mississippian smaller Foraminifera of Kentucky, southern Indiana, northern Tennessee, and south-central Ohio: Bull. Amer. Paleont., v. 43, no. 196, p. 129-368.

, and Conkin, B. M., 1967. Arenaceous foraminifera as a key to Upper Devonian and Lower Mississippian relationships in the type Mississippian area: Essays in Paleontology and Stratigraphy. R. C. Moore Commemorative Volume, Spec. Pap. Univ. Kansas, Dept. of Geol., no. 2, p. 85-101. , 1970. North American Kinderhookian (Lower , and Mississippian)naceous For am inif era: Com pte Rendu 6e Congress Intern. Strat. Geol. Carbonif., Sheffield, 1967, v. 2, p. 575-584. and , 1973a. Pre-Pennsylvanian Foraminifera of North America: XXII Int'l. Geol. Congress, India, 1964, p. 319335. Y

, 1973b. The paracontinuity and the determination of the Devonian-Mississippian boundary in the type Lower Mississippian area of North America: Univ. Louisville Studies in Paleont. and Strat. No. 1, Univ. Lou. Reprod. Serv., 36 pp. , and , 1975. The Dovonian-Mississippian and Kinderhookian-Osagean boundaries in the east-central United States are paracontinuities: Univ. of Louisville Studies in Paleont. and Strat. No. 4, Univ. of Lou. Reprod. Serv., 54 pp. Loeblich, A. R., Jr., and Tappan, H., 1964. Sarcodina, chiefly "Thecamoebians" and Foraminifera. In: Moore, R. C., Ed., Treatise on Invertebrate Paleontology. New York: Geol. SOC. Amer., and Univ. Kans. Press, pt. C, v. 1, p. i-xxxi, Cl-C510a.

59

Discussion Dr. R. A. Olsson: Have you done any work on the facies relationships of these fauna? Dr. J . E . Conkin: Well, we d i d n ' t have space in the paper t o go into facies. Agglutinate foraminiferans can, and d o , occur i n great abundance in some Paleozoic limestones, such as the Upper Devonian Louisiana Limestone of northeastern Missouri and western I l l i n o i s (sublithographic limestone bearing much fine-grained s i l t ) which carries a magnificent agglutinate foraminifera1 fauna. Here's a paper [Conkin and C o n k i n , 1964, Devonian Foraminifera, Part 1 - The Louisiana of Missouri and I l l i n o i s : Bull. Amer. Pal., v . 47, no. 213, pp. 53-105, pls. 12-15, text-figs. 1-5, charts 1-31 on i t . I d o n ' t say t h e r e ' s no ecological control for there i s a l ways some. For example, in sparry bioclastic limestone there are few agglutinate foraminiferans f o r often n o t enough det r i t a l grains are available for building t h e i r t e s t s ; the Lower Mississippian (Osagean) Burl ington Limestone of Missour i and I l l i n o i s bears no agglutinate foraminiferans for t h i s reason. I n the essential equivalent of the Burlington Limestone, the New Providence Shale of northwestern Kentucky and southern I n d i a n a , agglutinate foraminiferans are f o u n d . I n some shales and s i l t s t o n e s units in the Osagean Brodhead Formation o f Kentucky and Indiana ( i n which very few and/or poorly preserved arenaceous foraminiferans are f o u n d ) , there are occasional intercalated limestone or ironstone nodules and lenses which produce, upon acidization, well preserved agglutinate foraminiferans. Some agglutinate species have quite restricted stratigraphic ranges such as Hyperammina kentuckyensis which i s a definitive Osagean marker occurring in b o t h limestones and shales. I n general, we may say t h a t in Mississippian limestone facies, the tournayellids and endothyrids are dominant while i n the shale facies the agglutinate foraminiferans dominate.

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61 LATE PALEOZOIC OSTRACODES OF WESTERN EUROPE AND NORTH AMERICA: A REVIEW L u i s C. Sanchez D e Posada

U n i v e r s i d a d d e O v i e d o , O v i e d o , Espana

ABSTRACT

it is perhaps due t o t h e f a c t t h a t ostracodes have proved to be succ e s s f u l i n so many d i f f e r e n t environments adapting themselves t o every vari a t i o n i n :emperature, s a l i n i t y , water energy, s u b s t r a t m , depth, t h a t t h e y o f t e n sei? l e s s u s e f u l f o r b i o s t r a t i g r a p h i c a l a p p l i c a t i o n s , a t l e a s t a s f a r a s 1ong-d:siince c o r r e l a t i o n s a r e concerned. On t h e one hand we observe several !ong-ranging s p e c i e s , which p e r s i s t i n diachronous f a c i e s and on t h e other &and t h e r e exist many groups which are a b l e to s u r v i v e small f a c i e s c i i a y e s w i t h small changes in t h e i r morphology. The b i o s t r a t i g r a p h i c use o f Paleozoic ostracodes is f u r t h e r hampered b3 t h e f a c t that up to now we have only t h e r a t h e r i s o l a t e d r e s u l t s of work ostracodes from d i f f e r e n L areas and environments a t our d i s p o s a l . T h i s s i t u a t i o n may improve w i t h i n t h e forthcoming y e a r s as has been shown by t h e d'scovery o f so-called s i l i c i f i e d Devonian faunas and Devonian-CarbonlferHowever, at she p r e s e n t time t h e s e a r e o n l y ou8 entomozoacean faunas. k n c m from northwestern Europe, Spain, Portugal, and ilorth America. A t t h e s m e time attempss are being made t o come t o long-distance c o r r e l a t i o n s o f :'?per Devonicr and 9inan:ian assemblages betveen t h e USSR and western Surope by ~?ussiano s t r a c o d o l o g i s t s . In Euurope, she a t t e n t i o n o f Devonian t o Permian ostracode workers has up to nod T a i n l y been concentrated on d e s c r i p t i v e palaeontology and i n t h e l a s t decade 0% p l a e o e c o l o g y . RfSUMi C ' e s t un f a < t que l e s ostracodes o n t rgussi & s ' a d a p t e r 'a beaucoup d ' e n u i r o n n e ~ e n t sdi;;r^e'rerts e t h beaucoup de v a r i a t i o n s de l a tempgrature, de l a sa:initi, de l ' E w r g i e d'eau, de ;a s o u s t r a t e e t de l a profondeur. ~ ' e a :peut-&re h cause de c e c i q?ie l e e ostracodes semblent Ptre moins util e s quans a m a p p l i c a t i o n s b i o s t r a t i g r a p h i q u e f , du moins en ce q u i touche ! e s c o r r e l a t i o n s de longue-portei. D 'un c d t e , on remarque p l u s i e u r s e s pbces h grsnde ,&is;ribu$ion, qui p e r s i s z e n t dans des f a c i e s diachroneuz. De 1 ' a u t r e A t e , il y 2 beaucoup de groupes qui a r r i v e n t h surmonter l e s changenents de p e z i t s f a c i e s avec des changements vinimes dans l e w morphologie. 3e p l u s , l ' u t i l i z a t i o n b i o s t r a t i g r a p h i q u e des ostracodes palakozoiques e a t entrovge par l e f a i t que j u a q u ' i c i , oi: n ' a v a i t eu que des r 6 s u l t a t s isole's sur des ostracodes provenant des rdgions e t des environnements d i p & e n t s . C e t t e s i t u a t i o n p o u r r a i t s'mnZliorer dans 1 ' a v e n i r avec l e de'couvert des soi-disant faunes de'voniennes e t des faunes entomozoacdennea du Divonie n - C a r b o n i f b e . Cependent, pour l e moment, e l l e s ne sont connues qre pour l a p a r t i e cordouest de 1 'Europe, l 'Espagne, l e Portugal e t l 'Amirique du !lord. En rnzrnmo temps. des o s t r a c o d o l o g i s t e s r u s s e s f o n t des e f f o r t s p o w arr i v e r a m c o r r e l a $ i o n s de longue-portke e n t r e 1 'U.R.S.S. e t 1 'Europe de 1 ' Guest pour l e s assemblages du Divonien SupGrieur e t du Dinantien. En Europe, j u s q u 'ici i 'inte'r&?t des recherche6 sur l e s ostracodes du D6vonien jusqu'au P e n i e n a e'te' place' 6w l a p a l e b n t o l o g i e d e s c r i p t i v e e t d i n s l e s diz dernidres anne'es, sur l a palebe'cologie.

INTRODUCTION T h e r e e x i s t s a n e x t e n s i v e l i t e r a t u r e on l a t e P a l e o z o i c ost r a c o d e s from b o t h N o r t h America and w e s t e r n E u r o p e .

Amongst

t h e many p a p e r s w e may q u o t e t h e work by JONES AND KIRBY o n Eur o p e a n o s t r a c o d e s i n t h e p a s t c e n t u r y , and t h a t of U L R I C H and BASSLER $t t h e end of t h e 1 9 t h and b e g i n n i n g of t h e 2 0 t h c e n t u r y , who i n v e s t i g a t e d t h e N o r t h American f a u n a s .

Their funda-

m e n t a l s t u d i e s h a v e b e e n c o n t i n u e d by a l a r g e number of o s t r a code w o r k e r s s i n c e t h e F i r s t World War.

62

I n E u r o p e , l a t e P a l e o z o i c o s t r a c o d o l o g i s t s h a v e b e e n esp e c i a l l y a c t i v e i n Germany a n d s u r r o u n d i n g a r e a s .

It was

t h r o u g h t h e i r i n v e s t i g a t i o n s , t h a t a f i r s t a t t e m p t w a s made t o u s e entomozoan and s i l i c i f i e d o s t r a c o d e f a u n a s f o r b i o s t r a t i graphical purposes.

The p a s t t e n y e a r s h a v e moreover shown a

growing i n t e r e s t i n t h e p a l a e o e c o l o g y o f t h e s e o s t r a c o d e s . I n N o r t h America, work on Devonian t o P e r m i a n o s t r a c o d e s h a s b e e n m a i n l y c o n c e n t r a t e d on d e s c r i p t i v e p a l a e o n t o l o g y r a t h e r t h a n on b i o s t r a t i g r a p h y , a l t h o u g h i n t h e l a s t d e c a d e t h e r e i s a t e n d e n c y t o r e v i e w t h e i r v a l u e f o r i n f r a - and i n t e r b a s i n a l

correlations. I n comparison w i t h post-Paleozoic o s t r a c o d e s t h e s t u d y of P a l e o z o i c o s t r a c o d e s h a s b e e n l e s s i n t e n s i v e on t h e w h o l e as shown by t h e p a p e r s r e a d d u r i n g t h e p a s t f i v e o s t r a c o d e sympos i a a t N a p l e s , H u l l , P a u , Newark, and Hamburg.

I t should be

k e p t i n mind of c o u r s e , t h a t 1 2 P a l e o z o i c o s t r a c o d e w o r k e r s m e t s e p a r a t e l y a f t e r t h e Hamburg symposium a t G o t l a n d , w h e r e e i g h t non-published progress r e p o r t s have been discussed.

It is also

c u r i o u s t o n o t i c e how s e v e r a l y o u n g e r d i s c i p l i n e s w i t h i n t h e f i e l d of Paleozoic micropalaeontology,

such

BS

conodont, a c r i -

t a r c h s , c h i t i n o z o a n s , palynolomorphs and f o r a m i n i f e r s have y i e l d e d world-wide a p p l i c a b l e c o r r e l a t i o n s , w h e r e a s t h e b i o s t r a t i g r a p h i c v a l u e of o s t r a c o d e s i s s t i l l i n d i s c u s s i o n . I n t h i s c o n t e x t it appears t o be impossible t o p r e s e n t a t t h i s moment u n i f o r m b i o s t r a t i g r a p h i c o s t r a c o d e r a n g e c h a r t s which c a n b e u s e d on b o t h s i d e s o f t h e A t l a n t i c .

LOWE2 DEVONIAN Canada and A l a s k a Lower Devonian t o M i s s i s s i p p i a n o s t r a c o d e s i n Canada were r e v i e w e d by COPELAND (1972). G e d i n n i a n a s s e m b l a g e s , c o n t a i n i n g s e v e r a l t h l i p s u r i d and b e y r i c h i i d genera and P o l o n i e l l a s p e c i e s have been d e s c r i b e d from Quebec (BERDAN (COPELAND, 1 9 6 2 ) .

&

COPELAND

&I

BURK,

1 9 6 5 ) a n d N e w Brunswick

Upper Emsian o s t r a c o d e s , i n c l u d i n g many

b e y r i c h i i d s and t h e f i r s t d i v e r s i f i e d hollinomorphs have been d i s c o v e r e d i n A l a s k a a n d Yukon T e r r i t o r y (BERDAN 1973).

&

COPELAND,

The l a t t e r f a u n a a l s o c o n t a i n s s e v e r a l g e n e r a which a r e

known from t h e Lower Devonian o f E u r o p e , s u c h a s A c a n t h o s c a p h a ,

63

Tricornina, Beecherelia, Berounella, Praepilatina and Poloniella. U.S.A. Gedinnian faunas have been described by among others LUNDIN (1968) from Oklahoma and Tennessee (cf. also WILSON, 1935) with many thlipsurid species and Poloniella. Emsian thlipsurid faunas have been described from Tennessee (BASSLER, 1941) and Siegenian thlipsurid faunas have been described from West Virginia (ULRICH and BASSLER, 1913) and Pennsylvania (SWART2, 1932) Germany Czechoslovakia When JORDAN (1970) reviewed the Paleozoic ostracodes of Central Europe, he listed several species of Tricornina, Acanthoscapha and hollin3morphs from the Siegenian-Emsian of the German Democratic Republic, including an unidentified species of Polyzygia from the Emsian. BECKER & BLESS 11974) considered several species of Zygobeyrichia, Kozlowskiella, Polon+ella, Carinokloedenia and Bassleratia to have some biostratigraphical value for a regional subdivision of Emsian strata in the Rhenisch Mountains. Kozlowskiella also occurs the Upper Emsian of Czechoslovakia (PRIBYL, 1962). _ I

.

Acantoacopha Beccherella

62

Plo9ionephrodss

Bcrounellidr

0

Polonleila

Bcyrlchlocco ather than

@3

PoIyZygIo

treposelllmd*

a

Corboniia group

sI

Prmiopsocean Processobaiidm

Entomomids

,

i i

Fig. 1.

a

Kirkbyoccon

p~

Kloedenellacem

?

4

Rectonar (doe

a

Thlipsurids

w

Traporellinids

@

Tricirninidae

W

Hollinomorphs

0

Heaidlacean

J \

Mouryello

Schematic distribution of some ostracod groups in Lower Devonian strata

64

France The b e y r i c h i i d o s t r a c o d e s which have b e e n d e s c r i b e d from t h e S i e g e n i a n of Normandy (WEYANT, 1 9 6 5 , 1 9 6 6 ) t o g e t h e r w i t h a t h l i p s u r i d s p e c i e s and a d i v e r s i f i e d a s s e m b l a g e of P o l j z y g i a show l i t t l e i n common w i t h e i t h e r N o r t h America ( e x c e p t f o r a l o c a l s p e c i e s of O c t o n a r i a ) o r German f a u n a s . Carnic A l p s BANDEL & BECKER,

1 9 7 5 , s t u d i e d s i l i c i f i e d o s t r a c o d e s from

t h e Upper S i l u r i a n t o Lower C a r b o n i f e r o u s of t h e C e n t r a l C a r n i c Alps.

The f a u n a s a r e c h a r a c t e r i z e d by t h e predominance of

d i s t i n c t , r e l a t i v e l y few and l o n g - r a n g i n g s y s t e m a t i c u n i t s . Spain MICHEL ( 1 9 7 2 ) d e s c r i b e d f i v e s p e c i e s of P o l y z y g i a from

S i e g e n i a n and Emsian o f n o r t h w e s t e r n S p a i n . Conclusions B e y r i c h i i d o s t r a c o d s s . 1. and P o l o n i e l l a s . 1. a r e known from b o t h s i d e s o f t h e A t l a n t i c , a l t h o u g h no c l e a r r e l a t i o n s h i p s even a t g e n e r i c l e v e l c a n b e o b s e r v e d .

Thlipsurid ostra-

c o d e s e x c e p t P o l y z y g i a a p p e a r t o be w i d e s p r e a d i n t h e Lower Devonian o f N o r t h America b u t t h e y t e n d t o become r a r e i n t h e Emsian. T h i s g r o u p of o s t r a c o d e s i s p r a c t i c a l l y a b s e n t i n w e s t e r n Europe, where o n l y one s p e c i e s h a s b e e n d e s c r i b e d from Normandy. I n w e s t e r n Europe t h e t h l i p s u r i d genus P o l y z y g i a i s a b u n d a n t i n Normandy and S p a i n w i t h one s p e c i e s o c c u r r i n g i n

German Democratic R e p u b l i c .

-'e r e l l a

Genera l i k e A c a n t h o s c a p h a , Beech-

T r i c o r n i n a , and P r a e p i l a t i n a , which seem t o be r e s t r i c t -

ed t o r a t h e r q u i e t , low e n e r g y f a c i e s ( c f . J O R D A N , 1 9 7 0 ) o c c u r a t s e v e r a l p l a c e s i n Lower Devonian s t r a t a where t h e e n v i r o n m e n t a l c o n d i t i o n s a p p e a r t o have b e e n f a v o r a b l e f o r s u c h assemblages.

They c o n t a i n few marker s p e c i e s i n g e n e r a l and s e v e r a l

of t h e g e n e r a r a n g e i n t o Upper Devonian and D i n a n t i a n .

MIDDLE DEVONIAN Canada The E i f e l i a n of Eilesmere I s l a n d h a s y i e l d e d s e v e r a l s p e c i e s of P o l o n i e l l a

(WEYANT,

1968).

BRAUN,

1966 described

G i v e t i a n a s s e m b l a g e s from t h e N o r t h w e s t T e r r i t o r i e s w i t h p r i m i t s i o p s i d and q u a s i l l i t i d forms and P o l o n i e l l a .

McGILL

(1967)

d e s c r i b e d p o o r l y d i a g n o s t i c o s t r a c o d f a u n a s from t h e G i v e t i a n of t h e Northwest T e r r i t o r i e s , which h e compared w i t h f a u n a s of

65

similar age in Germany. McGILL 21966) discovered primitiopsid ostracodes from the Givetian of Alberta, U.S .A. Rich and diversified hollinomorph assemblages have been described from the Lower Eifelian of Ohio (KESLING & PETERSON, 1958), the Givetian of Michigan (KESLING & TABOR, 1953; KESLING, 1952; KESLING & McMILLAK, 1952) and the Givetian of Ontarie (KESLING, 1952). The Givetian of Ontario has also yielded quasillitid ostracodes and several species of Poloniella (cf. STUMM & WRIGHT, 1958) , Treposellinid (Hibbardia), quasillitid and thlipsurid ostracodes have been found in the Givetian of New York (SWARTZ & ORIEL, 1948). Thlipsurid and hollinomorph ostracodes from the Eifelian of Pennsylvania have been described by SWARTZ & SWAIN (1941). KESLING & KILGORE (1952) and KESLING & WEIS (1953), discovered thlipsurid and quasillitids from the Givetian of Michigan. KESLING (1954) described Poloniella from the Upper Eifelian of Ohio. ULRICH (1891) and KESLING (1955) described treposellinid species from the Eifelian of Kentucky and the Givetian of New York, respectively, Germany- & Poland Endemic black shale faunas of Upper Eifelian age occur in Thuringia with high percentages of Tricornina, Hlubocepina and healdiid ostracodes (K. ZAGORA, 1967). Significant markers are the genera Jenningsina and Poloniella. Silicified ostracode assemblages of presumably low-energy environments with Acanthoscapha, Beecherella, Berounella, Tricornina, Jenningsina and several hollinomorphs occur in the Eifelian of the Harz (BLUMENSTENGEL, 1969) and Vogtland (JORDAN, 1965). Treposellinid (Kozlowskiella, Parakozlowskiella) , hollinomorphs, quasillitid,primitiopsid and Polyzygia appear to be important regional guides in the Eifelian of Poland (ADAMCZAK, 1968) and the Eifelian-Givetian boundary of the Rhenish Mountains (BECKER, 1964, 1965, 1969, 1970, GROOS, 1969, KROMMELBEIN, 1950, 1953, 1955, BECKER & BLESS, 1974). Czechoslovakia POKORNY (1951) described some ostracodes occurring in Middle Devonian of Czechoslovakia, among others fuesillitids, hollinomorphs and primitiopsids.

-

66 (1

MIDDLE DEVONIAN

BULTIYNCK (1967) cited Polyzygia from the Eifelian of the Dinant Basin, Spain The genus Polyzygia is widely distributed in Eifelian and Givetian strata of NW Spain (MICHEL, 1972). Primitsiopsid, hollinomorphs and quasillitid ostracodes together with the genera Acanthoscapha, Tricornina, Berounella, Poloniella and Praepilatina occur in the Eifelian of NW Spain (BECKER & SANCHEZ DE POSADA, and BECKER et al., in Press). Conclusions Treposellinid ostracodes are distinctive elements from the Middle Devonian in both North America and Europe, As in the case of the Lower Devonian thlipsurid genera, treposellinid genera appear to exclude each other on both sides of the Atlantic. Hibbardia and Treposella being restricted to North America, whereas Kozlowskiella and Parakozlowskiella occur in Europe (Germany and Poland) and Australia (PRIBYL, 1962). It should be noted, however, that it is not clear to me, whether Hibbardia appears to possess a more distinct dolonoid scar than

67

Parakozlowskiella. Whether this phenomenom should be considered to be a specific or generic character remains open for discussion. Poloniella s.1. (including Dizyglopeura and Framella as subgenera) and quasillitids are characteristic of many Middle Devonian strata, However species are usually restricted to a single basin and do not permit long distance correlations. The same is true of hollinomorphs, which according to BECKER & BLESS (1971) appear to have migrated in time and space from North America to Europe during the Devonian and Carboniferous, the different genera showing a clear diachronism. The low energy environments containing Tricornina, Acanthoscapha, Berounella, Beecherella, have not been described in North America. The similarity at the specific level between certain German and Spanish Lower Fifelian faunas may be due to similar facies conditions hence their stratigraphical use remains uncertain.

UPPER DEVONIAN Canada Large Frasnian ostracode faunas from Alberta and Northwest Territories containing amongst others several species of gionephrodes, and quasillitids (Eriella, Quasillites! seem to have some similarities with Russian Platform faunas of similar age. LORANGER, 1954, 1963, 1965; McGILL, 1963; BRAUN, 1963, 1968; LORANGER, 1971, describes a Frasnian fauna containing amongst others several entomozoan ostracods which may permit comparison with entomozoan faunas from NW Europe. The apparent absence of hollinomorphs is remarkable. U.S.A. GIBSON (1955) described a fauna from the Cerro Gordo Formation of Iowa containing primitiopsid ostracodes. STEWART & HENDRIX (1945) described rather heterogeneous ostracode assemblages containing some entomozoan species from the Frasnian of Ohio. KESLING & PLOCH, (1960) studied a probably endemic cypridinacean species from the Upper Devonian Black Limestone (Frasnian/Famennian). The absence of hollinomorphs is again remarkable. Germany and Poland BLUMENSTENGEL (1965) described a rich Frasnian/Famennian

e-

68

silicified fauna from lhuringia, with hollinomorphs, Acanthoscapha, Tricornina, Berounella, Processobairdia among others. This fauna has shown to be useful for regional zonation. The Frasnian fauna from the Harz described by BLUMENSTENGEL (1969) also contains Acanthoscapha, Berounella, Tricornina and hollinomorphs but there is very little similarity between the two faunas at specific level. However GRUNDEL (1962) BLUMENSTENGEL (1954) described a rich entomozoan fauna from Thuringia which can be directly compared with the Frasnian/Famennian entomozoan faunas from the Rhenisch Mountains (RABIEN, 1954). KRCMMELBEIN (1954); BECKER (1967, 1968 , 1970) GROOS, (1969), have described rich and diversified ostracod assemblages from the Frasnian of the Rhenisch Mountains which contained several species of Polyzygia, Plagionephrodes, Primitiopsacea, Poloniella, and hollinomorphs. Entomozoan ostracodes also appear in the Upper Devonian of Poland (cf. JORDAN, 1970). Papers by RABIEN, (especially RABIEN, 1954) represent an important attempt to obtain a zonation with entomozoan ostracods and this zonation with minor modifications seems to be mainly accepted in Europe. Fig. 7 shows the Upper Devonian and lowermost Carboniferous entomozoan zonation after BECKER & BLESS (1974). The Richterina ( g . ) aff. latior Zone is proposed by BECKER & BLESS (op. cit.) and characterized by the presence of ostracodes described as 5. ( 5 . ) aff. latior by GRUNDEL (1961, 1963) JORDAN & BLESS (1970) and SANCHEZ DE POSADA & BLESS (1974). This zone is supposed to be equivalent to the Middle-Upper Tournaisian and part of the Visean. France and Belgium -LETHIERS (1970, 1972, 1974) described ostracode faunas ranging from Frasnian to Tournaisian age containing, amongst others, Polyzygia,- Quasillitidae, and several entomozoan species. BECKER & BLESS (1974) noticed that the stratigraphical range of some of the species described by LETHIERS does not coincide with that observed by themselves suggesting that Upper Famennian benthonic ostracodes of the Dinant Basin had been clearly facies controlled in their lateral and vertical distribution.

69

LETHIERS (1974b) proposed a preliminary zonation for ostracodes from Frasnian to lowermost Tournaisian in the Dinant Basin. However, as ye this zonation has not been tested outside of the area in which it was established. Sjain Little is known about Upper Devonian ostracodes in Spain. BLESS & MICHEL (1967 studied a silicified ostracod fauna from northwestern Spain containing among others Acratia,-Bohemina, Ceratacratia, Processobairdia, Ectoplacera and Tricornina. This fauna has been compared with the fauna described by BLUMENSTENGEL (1965) from the Upper Devonian in Thuringia, the age established from the ostracodes is in agreement with that obtained from conodonts and cephalopods. In addition MICHEL (1972) has described 2 species of Polyzygia in Frasnian strata of northwestern Spain. Conclusions Upper Devonian entomozoan ostracode faunas seems to be very useful for stratigraphical purposes, at least in Europe, and entomozoan zonation may be correlated with the orthochronological scale. Benthonic ostracodes are occasionally useful in regional correlations. LOWER C A R B O N I F E R O U S E U RO PE A N FA U N A S AND M I S S I S S I P P I A N AMERICAN FAUNAS

Recent progress in correlation techniques in Carboniferous strata of Europe and North America coupled with the difficulty of not knowing the exact stratigraphical level from which some ostracode faunas (described many years ago) have been obtained, has necessitated that Chester ostracodes from North America should be treated together with Lower Carboniferous European faunas

.

Canada GREEN (1963) described rich and diversified ostracodes assemblages from the Banff Formation of Alberta containing among others hollinomorphs, Kirkbyacea, Beyrichiopsidae, Kloedenellacea, Healdiidae, Paraparchitacea, rich quasillitids, some Berounellidae, Beecherellidae, Bythocytheridae and Entomozoidae. LORANGER (1958) divided the Rundle Formation into a

70

Lower Criboconcha zone and an upper Paraparchites carbonarius zone. Other Mississippian ostracodes in Canada were described by COPELAND (1957), BELL (1960) and BLESS & JORDAN (1971). U.S.A. Carboniferous and Permian ostracodes described in U.S.A. wete compiled by ECHOLS & CREATH, 1959. Most of the known Carboniferous occurrences are in the interior region outside the area of this paper.

Great Britain JONES ( 1 8 8 4 ) and JONES & KIRKBY k 8 7 4 ) described in many publications a great number of ostracodes in the British Isles covering the whole Carboniferous at the end of last century. Most of these species need revision now. As far as we know only a few of the lower Carboniferous species have been restudied. ANDERSON (1970) dealt with species of the genus Carbonita.

DEVONIAN

Fig. 3 Schematic distribution of some ostracode groups in Upper Devonian strata.

71

ROBINSON (1959) described an ostracod fauna from the Cowdor Quarry in Derbyshire containing among others Tetrasac-culus 1 Kirkbyacea, Discoidella, Paraparchitacea, Monoceratina and Healdicea. Germany KUMMEROW 1939) described 80 species from Lower Carboniferous strata of Germany and Belgium containing among others Hollinellidae Kirkbyacea, Bairdiacea, Berounellidae, Glyptopleuridae and Entomozoidae. GRUNDEL (1961) described more than 60 species from the Gattendorfia-stufe. The faunas are mainly composed of Tricorninidae, Kirkbyacea, Healdiidae, Rectonariidae, Bairdiidae, Cypridinadae, Monoceratina, Triceratina and Entomozoidae. Ostracod faunas described by GRUNDEL (1962) from the CU 11 from the southern border of the Ruhr Carboniferous B/Y area contained mainly Rectonariidae, Tricornina, Glyptopleuridae, Healdiopsis and Entomozoidae. Two species, Glyptopleura elapa and Richterina (R.) aff. latior a r e related to species described in 1974 by SANCHEZ DE POSADA & BLESS from Aprath (Federal Republic of Germany). BECKER & BLESS (1974) reviewed the stratigraphical range of the species described from the Lower Carboniferous of Dinant Basin by DE KONINCK. (1840, 1844) ,JONES & KIRKBY (1874), TSCHIGOVA (1970), ROME (1971) and ROME & GOREUX (1960). Some of the species named under open nomenclature are figured in the above papers; some of them are compared with previously described species, and their stratigraphical range has been proposed. Nine ostracod zones ranging from Fa2a to V3 have been proposed. Belaium ROME & GOREUX (1960) described nine species of Cryptophyllus from Strunian strata. ROME (1971) described several species of Kegelites, Beyrichiopsis, Sansabella, Bairdia, Silenites, Microcheilinella, and Paraparchites. Some of the species of Bairdia described by ROME are considered to belong to a single species (LETHIERS, 1975). BECKER & BLESS (1974) studied ostracodes in the Dinant Basin of Germany and Belgium (see above). BECKER & BLESS (1974) figured and described some species occurring in Fr2 strata in the Belgian part of the Dinant Basin. Special attention is

12

p a i d t o B e y r i c h i o p s i s g l y p t o p l e u r o i d e s GREEN and t o a g r o u p of s i m i l a r ( i f n o t i d e n t i c a l ) s p e c i e s composed o f " B e r n i x " v e n u l o s a KUMMEROW

( 1 9 3 9 ) , P s e u d o l e p e r d i t i a p o o l e i SOHN ( 1 9 6 9 ) and

p.

t u b e r c u l i f e r a SCHNEIDER (1956) a l l of which a r e c o n s i d e r e d t o p r o b a b l y have some v a l u e i n l o n g - d i s t a n c e c o r r e l a t i o n s .

g.

g l y p t o p l e u r o i d e s i s known from t h e uppermost Famennian and lower most T o u r n a i s i a n s t r a t a i n t h e USSR, Europe and Canada. The g r o u p of P,. p o o l e i ,

g. t u b e r c u l i f e r a and " B e r n i x " v e n u l o s a

i s known from D i n a n t i a n s t r a t a i n U S A , t h e F e d e r a l R e p u b l i c of Germany and USSR. BLESS & THOREZ (& BECKER e t a l . , 1 9 7 4 ) d i s t i n g u i s h e d f o u r o s t r a c o d e s a s s e m b l a g e s , two o f which o c c u r i n l i m e s t o n e b e l i e v e d t o r e p r e s e n t a r e l a t i v e l y d e e p s u b t i d a l environment, t h e o t h e r occurred i n limestones b e l i e v e d t o have been d e p o s i t e d i n a n i n t e r t i d a l and a s u p r a t i d a l e n v i r o n m e n t . Poland BLASZYK & NATUSIEWICZ ( 1 9 7 4 ) d e s c r i b e d 3 4 o s t r a c o d e s p e c i e s from D i n a n t i a n and Namurian s t r a t a i n n o r t h w e s t e r n P o l a n d .

Only one s p e c i e s i s r e l a t e d t o p r e v i o u s l y d e s c r i b e d s p e c i e s from Europe, f o u r a r e i d e n t i c a l and two are r e l a t e d t o American species. Spain JORDAN & BLESS ( 1 9 7 0 ) d e s c r i b e d two s p e c i e s of entomozoid

O s t r a c o d a o c c u r r i n g i n T o u r n a i s i a n s t r a t a of n o r t h w e s t e r n S p a i n and f i g u r e d s e v e r a l s p e c i e s of K i r k b y a , A c r a t i a and T r i p l a c e r a . Conclusions Entomozoan O s t r a c o d a seem t o be u s e f u l f o r s t r a t i g r a p h i c a l p u r p o s e s i n some Lower C a r b o n i f e r o u s s t r a t a from Europe b u t a l o t of work h a s s t i l l t o be done c o n c e r n i n g t h i s s u b j e c t . BECKER & BLESS

(1974)

( i n BECKER

g . )cited

several

s p e c i e s of B e r n i x , B e y r i c h i o p s i s and P s e u d o l e p e r d i t i a a s p o s s i b l e index f o s s i l s f o r long d i s t a n c e c o r r e l a t i o n s . A most i n t e r e s t i n g a s p e c t o f t h e o s t r a c o & f a u n a on b o t h

s i d e s of t h e A t l a n t i c i s t h e a b s e n c e i n N o r t h America of T r i c o r n i n i d a e and R e c t o n a r i i d a e .

On t h e o t h e r hand t h e most

s t u d i e d American Lower C a r b o n i f e r o u s f a u n a s p o s s e s s a g r e a t e r v a r i e t y of s p e c i e s of h o l l i n o m o r p h s , K i r k b y a c e a , B a i r d i a c e a and H e a l d i a c e a .

73 UPPER CARBONIFEROUS

U.S.A. Most of t h e p a p e r s o n P e n n s y l v a n i a n o s t r a c o d e s d e a l w i t h faunas r e s t r i c t e d e i t h e r s t r a t i g r a p h i c a l l y o r g e o g r a p h i c a l l y . COOPER ( 1 9 4 6 ) , BRADFIELD ( 1 9 3 5 ) , and KELLETT

(1933, 1934, 19351,

however, d e s c r i b e l a r g e and d i v e r s i f i e d f a u n a s from t h r o u g h o u t t h e P e n n s y l v a n i a n of I l l i n o i s and a d j a c e n t a r e a s o f I n d i a n a and Kentucky, t h e Ardmore B a s i n i n Oklahoma and t h e Upper P e n n s y l vanian i n t o Permian of Kansas, a l l of which are o u t s i d e t h e a r e a of t h i s s t u d y .

T h e s e f a u n a s a r e m a i n l y composed o f H o l l i -

n e l l a , Kloedenellacea, Kirkbyacea, Paraparchitacea, Bairdiacea, and H e a l d i a c e a .

L i t t l e can be s a i d about t h e u s e f u l n e s s of t h e

d e s c r i b e d s p e c i e s f o r s t r a t i g r a p h i c a l p u r p o s e s as m o s t o f them

seem t o h a v e a r a t h e r l o n g s t r a t i g r a p h i c a l r a n g e and o n l y a c o m p a r a t i v e l y s m a l l number h a v e a r e s t r i c t e d r a n g e ( c f . C O O P E R , 1 9 4 6 , p . 18; KELLETT, 1 9 3 3 , p . 6 1 ) . SHAVER,

( i n Thomson e t a l . , 1 9 5 9 ) d e s c r i b e d a n o s t r a c o d e

f a u n a from K e n t u c k y , B a i r d i a c e a and K i r k b y a c e a b e i n g t h e p r e d o m i n a n t e l e m e n t s t h e r e i n . SHAVER & SMITH ( 1 9 7 4 ) d e s c r i b e d 1 5 s p e c i e s o f K i r k b y a c e a from Lower and M i d d l e P e n n s y l v a n i a n s t r a t a of I n d i a n a and K e n t u c k y .

The A_. r o t h i f a u n a i s f o u n d i n

rocks belonging t o t h e P r o f u s u l i n e l l a zone whereas t h e

5.

c e n t r o n o t u s f a u n a i s f o u n d i n r o c k s of t h e z o n e s o f F u s u l i n e l l a and F u s u l i n a . Lower P e n n s y l v a n i a n non-marine o s t r a c o d e s from t h e S . A p p a l a c h i a n s were d e s c r i b e d by SCOTT

&

SUMMERSON ( 1 9 4 4 ) .

They

included a s p e c i e s , Cypridina r a d i a t a ( t y p e s p e c i e s of Radiic y p r i d i n a BLESS, 1 9 7 3 ) , w h i c h i s common i n t h e Lower Westp h a l i a n of Europe.

74

MISSISSIPPIAN

ii

LOWER CARBONIFEROUS

Y

Fig. 4 Schematic distribution of some ostracode groups 4.n Lower Carboniferous and Mississippian strata.

'ENNSYLVANIAN

UPPER

CARBONIFEROUS

/,

/

"

/

I' \

.i

,

Fiq. 5 Schematic distribution of some ostracode groups in Uppe; Carboniferous and Pennsylvanian strata.

75 U P P E R C A R B O N I F E R O U S OF E U R O P E

Great Britain JONES and JONES & KIRKBY described in the last century some ostracodes occurring in the Upper Carboniferous of Great Britain, most of these are species of Geisina and Carbonita. As stated before species of Carbonita were reviewed by ANDERSON (1970). POLLARD (1966, 1969) described and noted the occurrence of several Geisina and Carbonita species in non-marine bands from the Coal Measures of Durham and Northumberland. BLESS & POLLARD (1973) studied the palaeocology and content of two ostracodeassemblages, one from Upper Westphalian A strata in The Netherlands, the other one from Lower Westphalian B in Great Britain. Only a small number of marine ostracodespecies are known from the Upper Carboniferous of Great Britain. RAMSBOTTOM, 1952 described some kirkbyacean and Roundyella species from the Similis pulchra zone. BLESS (1974) described the occurrence of several species of Hollinellidae (Hollinella and Jordanites) , Kirkbyacea, Roundyella, Moorites, Cornigella, Pseudoparaparchites, Healdia and Asturiella from the Croft's End Marine Band. Eleven of these species are conspecific or closely related to species of Pennsylvanian age in North America. Germany KUMMEROW (1953) described Upper Carboniferous ostracodes from Germany containing, among others, Paraparchitacea, Kellettina, and Kloedenellacea. Now the fauna needs to be restudied. KREMP & GREBE (1956), VANGEROW (1958, 1970), described nonmarine ostracodes mainly Kloedenellacea and Carbonita species. The Netherlands VAN DER HEIDE (1951) describes species of Carbonita, Geisina, and Qpridina in the Upper Carboniferous of The Netherlands. BLESS, JORDAN & MICHEL (1969) described a rather diversified ostracode fauna from the base of Westphalian C. This included: Hollinellidae, Kirkbyacea, Cornigella, Roundyella, Morrites, Paraparchitacea and Healdiacea. Twelve of these species are conspecific with species described by BLESS (1974) from the same horizon in Great Britain. BLESS (1974) described the new genus Cypridelliforma from the Lower Westphalian A of the Netherlands.

-

76

Spain BLESS (1965, 1967, 1968, 1970 - in VAN AMEROM g.), SANCHEZ DE POSADA & BLESS (1971), BECKER & BLESS (in BECKER g a1.,1375 ) described more than 40 species of Upper Carboniferous ostracodes in northwestern Spain (mostly in Upper Westphalian strata with only a small number from Namurian and Stephanian rocks). Most of the species which had been previously described from elsewhere are identical or closely related to Upper Pennsylvanian species from North America. The faunas are mainly composed of Hollinellidae (Hollinella and Jordanites) , Kirkbyacea, Roundyella, Bairdiacea and Healdiacea. However two genera, Jordanites and Asturiella do not occur in North America. Unpublished data of several localities in northwestern Spain show that some species which occur at the base of Westphalian C in The Netherlands and England are now known from the Westphalian A-B of northwestern Spain: Healdia sp. D (BLESS, JORDAN & MICHEL 1969) , Asturiella limburgensis BLESS, Pseudobythocypris pediformis (KNIGHT) and Rouridyella simplicissima (KNIGHT) Cavellina sp. cf. cumingsi described by BLESS AND by SANCHEZ DE POSADA & BLESS (1971) previously described from Upper Westphalian strata only in Spain has now also been found in Lower Westphalian rocks. A most interesting aspect of the Spanish Upper Carboniferous ostracodefauna is the presence of some ostracodes previously not known from so young strata as Upper Carboniferous, mainly Tricornidae (Tricornina (Sricorninq) and (Bohemina) and Rectonariidae (at least one probable species of Rectoplacera occurs), and Berounella. The occurrence of such ostracodes is believed to have a clear environmental control. All these o s tracods were found in limestones with silicified fauna or in shales (as internal and external molds) in sections without coal bearing strata. The same holds true for a silicified fauna composed of Myodocopida in limestones of Westphalian D age and for the entomozoan ostracode Truyolsina truyolsi described by BECKER & BLESS (in BECKER et a1.1974 ) from rocks of Namurian A age. Czechoslovakia PRIBYL (1958, 1962) described 4 3 ostracode species from the Namurian A of Czechoslovakia, containing amonc; others

.:

77

Carbonita, Hollinella, Healdiacea, Kloedenellidae, and Kirkbyacea. These bear a close relationship to American faunas from Chester and Morrow strata (cf. PRIBYL, 1962, p. 6). Conclusions Possibly due to the greater development of marine sequences in North America, Upper Carboniferous ostracodes in USA are more varied than in western Europe where only a relatively small number of marine faunas has been studied. The marine ostracodes of Europe have frequently been considered to have relationships with American ones (cf. PRIBYL, 1962, BLESS, 1974). Both American and European marine bands are mainly composed of Hollinellidae, Kirkbyacea, Kloedenellacea, Paraparchitacea, Bairdiacea, and Healdiacea. Some of the species are identical or closely related on both sides of the Atlantic. In Europe work was mainly done with non-marine ostracodes. Carbonita and Geisina are the more frequent genera. The presence in Upper Carboniferous strata of northwestern Spain of some ostracodes belonging to the Families Fricorninidae and Rectonariidae is remarkable.

-

PERMIAN

U.S.A.

HARRIS & LALICKER (1932) described Wolfcampian ostracodes from Oklahoma and Arkansas containing Paraparchitacea, Healdiacea and Kloedenellacea. Diversified assemblages of Hollinellidae, Kirkbyacea, Kloedenellacea and Bairdiacea were described from Wolfcampian strata of Kansas by KELLETT (1933, 1934, 1935) Wolfcampian and Lower Leonardian from Nebraska by UPSON (1935). Other Wolfcampian faunas were described by DELO (1930) and HARRIS & WORELL (1936). All of these are outside the present study area. HOLLAND (1934) and SCOTT (1942) studied unique non-marine species from West Virginia,

Fig. 6

Schematic distribution of some ostracode groups in

Permian strata.

79 England Permian o s t r a c o d e s from England were d e s c r i b e d i n t h e l a s t c e n t u r y by K I R K B Y . Germany

&

K i r k b y a c e a a r e t h e most r e m a r k a b l e e l e m e n t s .

Poland

Lower Z e c h s t e i n o s t r a c o d e s from Pommern h a v e b e e n des c r i b e d by KRb'MMELBEIN ( 1 9 5 8 ) .

The f a u n a c o n t a i n s s e v e r a l s p e -

c i e s of M o n o c e r a t i n a , R o u n d y e l l a , H e a l d i a c e a and B a i r d i a c e a , most of which had n o t b e e n p r e v i o u s l y d e s c r i b e d .

RICHTER and

REUSS d e s c r i b e d i n t h e 1 9 t h c e n t u r y o s t r a c o d f a u n a s from t h e

Z e c h s t e i n of Germany and i n 1968 J O R D A N r e v i e w e d t h e P e r m i a n o s t r a c o d e s d e s c r i b e d from t h e Z e c h s t e i n i n c e n t r a l E u r o p e .

REFERENCES Due t o r e a s o n of s p a c e t h e r e a d e r i s r e f e r r e d t o BECKER & BLESS,

1 9 7 4 and ECHOLS & CREATH,

1959 f o r m o s t r e f e r e n c e s d e a l -

ing w i t h o s t r a c o d e s d e s c r i b e d from Devonian and D i n a n t i a n s t r a -

t a of C e n t r a l and W e s t e r n Europe a s w e l l a s M i s s i s s i p p i a n , P e n n s y l v a n i a n and Permian s t r a t a of U.S.A. Amerom, H . W . J . v a n , B l e s s , M . J. M . , and W i n k l e r , P r i n s C . F . , 1 9 7 0 . Some p a l e o n t o l o g i c a l and s t r a t i g r a p h i c a l a s p e c t s of t h e Upper C a r b o n i f e r o u s Sama F o r m a t i o n ( A s t u r i a s , S p a i n ) . Med. R i j k s G e o l . D i e n s t , N.S., n . 2 1 , p p . 9 - 7 9 , p l s . 1 - 1 0 . Anderson, F . r 1 9 f 0 . a r b o n i f e r o u s O s t r a c o d a . The g e n u s C a r b o n i t a S t r a n d . B u l l . Geol. S u r v . G r e a t B r i t a i n , n . 32, DD. 69-121. ~ l s X . II-XIX. B a i i e l , D . , an& B e c k e r , G . , 1975. O s t r a c o d e n a u s p a l s o z o i s c h e n p e l a g i s c h e n K a l k e n d e r K a r n i s c h e n Alpen ( S i l u r i u m b i s U n t e r k a r b o n ) . Senck. l e t h . , Band 5 6 , p p . 1 - 8 3 , p l s . 1 - 8 . 1 9 4 1 . O s t r a c o d a from t h e Devonian (Onondaga) Bassler, R. S. c h e r t of West V i r g i n i a . Washington Acad. S c . J o u r . , v . 3 1 , pp. 2 1 - 2 7 . Becker, F . , B l e s s , M . J. M. , S t r e e l , M. , and T h o r e z , J . , 1 9 7 4 . P a l y n o l o g y and o s t r a c o d e d i s t r i b u t i o n i n t h e Upper Devonian and b a s a l D i n a n t i a n of Belgium and t h e i r d e p e n d e n c e on s e d i +. R i j k s G e o l . D i e n s t , N . S . , n . 25, p p . 9mentary f a c i e s . M 98, 30 p l s . Ostracode s t r a t i g r a p h y Becker, G . , and B l e s s , M. J . M . , 1 9 7 4 . of t h e Ardenno-Rhenisch Devonian and D i n a n t i a n . I n t e r . B e l g i a n Microp. l i m i t s , Namur, 1 9 7 4 , P u b l i c a t i o n n . 1, 52 p p . , 50 p l s . Becker, F . , B l e s s , M. J . M . , and Kullmann, J . , 1975. O b e r k a r b o n i s c h e E n t o m o z o e n - S c h i e f e r i m K a n t a b r i s c h e n G e b i r g e (NordP a l a o n t . Abh. 1 5 0 , p p . 9 2 - 1 1 0 . s p a n i e n ) . 5. Becker, G . , Mendez B e d i a , I . , and Sanchez d e P o s a d a , L . C . , ( i n p r e s s ) ; Una f a u n a d e o s t r i c o d o s d e l a f o r m a c i o n M o n i e l l o (Devonico, A s t u r i a s , NW d e E s p a n a ) . Nota p r e l i m i n a r . T r a b . Geol., n . 7 . Becker G . , and S a n c h e z d e P o s a d a , L . C . ( i n p r e s s ) . Ostracoda aus d e r M o n i e l l o F o r m a t i o n A s t u r i e n s (Devon; NW S p a i n ) Palaeontographica.

,

w.

Jb.

-

e.

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Robinson, J . E . , 1 9 5 9 . The o s t r a c o d e f a u n a o f t h e s h a l e f a c i e s of t h e Cowdor L i m e s t o n e s , n o r y h end o f Cawdor Q u a r r y . Q u a r t . J o u r . Geol. London, v . 1 1 4 , p p . 435-448. Sanchez d e o s a d a , L . C . , and B l e s s , M. J . M . , 1 9 7 1 . Una m i crofauna d e l Westphaliense C de Asturias. d e Microp a l e o n t . , v . 111, pp: 193-204, p l s . I , 11. , 1 9 7 4 . P r e l i m i n a r y n o t e on t h e Lower C a r b o n i f e r o u s O s t r a c o d s from A p r a t h ( F e d e r a l R e p u b l i c o f Germany). I n t e r n a t . 0" B e l g i a n M i c r o p a l e o n t . l i m i t s , Namur, 1 9 7 4 . P u b l i c a t i o n n. 2 , 5 p p . , 2 p l s . Some P e n n s y l v a n i a n k i r k b y S h a v e r , R . H . , and S m i t h , S . , 1 9 7 4 . a c e a n o s t r a c o d e s o f I n d i a n a and M i d - c o n t i n e n t S e r i e s t e r m i n o logy. P r o g r e s s , n . 3 1 , 59 p p . , 3 p l s . Sohn, I . G . , 1 9 6 0 . P a l e o z o i c sDecies of B a i r d i a and r e l a t e d g e n e r a . U.S. G e o l . S u r v . P r o f e s s . ,Paper 330A, 1 1 5 p p . , 6 p l s . 1 9 6 1 . A e c h m i n e l l a , Amphissltes, K i r k b y e l l a and rel- a.t _ e d g e n e-r a _. _ U . S . G e o l . S u r v . P r o f e s s . P a p e r 330B, p p . 107160, p l s . 7 - 1 2 . , ( i n Gordon e t a l . ) , 1 9 6 9 . R e v i s i o n of some G i r t y ' s i n v e r t e b r a t e f o s s i E =om t h e F a y e t t v i l l e S h a l e ( M i s s i s s i p p i a n ) of A r k a n s a s and Oklahoma. O s t r a c o d e s . Id. 606-F, pp. 41-55, p l s . 6-8. Sohn, I . G . , 1 9 6 9 . P s e u d o l e p e r d i t i a S c h n e i d e r , 1956 ( O s t r a c o d a , C r u s t a c e a ) a n e a r l y M i s s i s s i p p i a n g e n u s from S o u t h w e s t e r n Nevada. Id., 643C, p p . 1 - 6 , 1 p l . , 1 9 7 1 . N e w l a t e M i s s i s s i p p i a n O s t r a c o d e g e n e r a and s p e c i e s from N o r t h e r n A l a s k a . g., 7 1 1 A , pp. 1 - 2 4 , p l s . 1-9.

e.

Q~J.

=.of

.

=.=.

, 1 9 7 2 . L a t e P a l e o z o i c O s t r a c o d e s p e c i e s from t h e Con7 1 1 B , p p . 1-15, p l s . 1, 2 . terminous United S t a t e s . , 1975. M i s s i s s i p p i a n O s t r a c o d a of t h e Amsdem F o r m a t i o n ( M i s s i s s i p p i a n and P e n n s y l v a n i a n ) o f Wyoming. Id. 848G, p p . 1 - 2 2 , p l s . 1-3. S t e w a r t , G . A . , and H e n d r i x , W . E . , 1945. O s t r a c o d a of t h e Plum Broo S h a l e , E r i e C o u n t y , O h i o . Jour. P a l e o n t . , v . 1 9 , pp. 87-95, p l . 1 0 . Stumm, E . C . , and W r i g h t , J . D . , 1958. Check l i s t of f o s s i l i n v e r t e b r a t e s d e s c r i b e d from t h e M i d d l e Devonian r o c k s o f t h e Thedford-Arkona R e s i o n of S o u t h e a s t e r n O h i o . P a l e o n t . C o n t r . Michigan Univ. Museum, v . 1 4 , p p . 81-132. Swartz, F . , m 2 . R e v i s i o n of t h e o s t r a c o d e f a m i l y T h l i p s u r i d a e , w i t h d e s c r i p t i o n of a new s p e c i e s from t h e Lower Devoni a n of P e n n s y l v a n i a . P a l e o n t . v . 6 , p p . 36-58, p l s . 1 0 , 11. S w a r t z , F . , and O r i e l , S . S . . 1 9 4 8 . O s t r a c o d a from t h e M i d d l e Devonian’Windom Beds i n W e s t e r n N e w York. Penns l v a n i a C o l l . T e c h . , P a p e r 1 4 2 , p p . 541-566, p l s . S w a r t z , F . , and S w a i n , F . M . . 1 9 4 1 . O s t r a c o d e s o f t h e M i d d l e Devonian’ Onondaga Beds of C e n t r a l P e n n s y l v a n i a . G e o l . SOC. America v . 5 2 , p p . 381-458, p l s . 1 - 8 . S w e e t , W . C . , and B e r a s t r o m , S . M . . 1 9 7 0 . SvmDosium on Conoa . don; B i o s t r a t i g r a p h ; . =.’America 1 2 7 , 499 pp. Thompson, M. J . , and S h a v e r , R . H . , 1 9 6 4 . E a r l y P e n n s y l v a n i a n M i c r o f a u n a s of t h e I l l i n o i s B a s i n . T r a n s . I l l i n o i s S t a t e Acad. S c . , v . 5 7 , p p . 4-23, 1 p l . T h e o n T M . J . , S h a v e r , R . H . , and R i g g s , E . A . , 1959. E a r l y P e n n s y l v a n i a n f u s u l i n i d s and o s t r a c o d s of t h e I l l i n o i s B a s i n . J o u r . P a l e o n t . , v . 33, pp. 770-792, p l s . 104-107. U l r i c h , E . O . , and B a s s l e r , R . S . , 1 9 1 3 . S y s t e m a t i c P a l e o n t o l o g y Lower Devonian O s t r a c o d a Maryland Geol. S u r v . Lower Devonian volume, p p . 513-542, p l s . 95-98. Vanqerow, E. F . , 1 9 5 7 . M i k r o p a l d o n t o l o q i s c h e U n t e r s u c h u n s e n i n d e n K o h l s c h e i d e r S c h i c h t e n i m Wurmrevier b e i Aachen. J b . , Band 7 3 , p p . 457-506, p l s . 20-23. , 1 9 7 0 . D i e f a u n a d e s W e s t d e u t s c h e n O b e r k a r b o n s . pal a e o n t o g r . Band 1 3 4 , p p . 133-152, p l . 1 3 . Weyant, M . , 1 9 7 1 . Recherches m i c r o p a l 6 o n t o l o g i q u e s s u r l e P a l g o z o i c i n f k r i e u r e t moyen d e l ’ h r c h i p e l A r c t i q u e C a n a d i e n . U n p u b l i s h . Ph.D. t h e s e s Univ. Caen. W i l s o n , Ch. W . , 1 9 3 5 . The o s t r a c o d e f a u n a of t h e B i r d s o n g S h a l e , H e l d e r b e g , o f W e s t e r n T e n n e s s e e . Jour. P a l e o n t . , v . 9 , p p . 6 2 9 - 6 4 6 , p l s . 77-78.

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I

85 EARLY PALEOZOIC CONODONT BIOSTRATIGRAPfIY IS THE ATLANTIC BORDERLAHE S t i g M. B e r g s t r B m Department of Geology and Mineralogy, Columbus,

The O h i o S t a t e U n i v e r s i t y

O h i o 43210

ABSTRACT

Cambrian c o n o d o n t s ,

s t i l l r e l a t i v e l y p o o r l y known b u t a p p a r e i i t l y

w i d e s p r e a d i n t h e A t l a n t i c B o r d e r l a n d s , i n c l u d e s o m e 15 m u l t i e l e m e n t genera.

D e s c r i b e d f a u n a s a r e m a i n l y frsm S c a n d i n a v i a , P o l a n d , a n d

Germany ( e r r a t i c s ) w h e r e a s l i t t l e i n f o r m a t i o n i s a v a i l a b l e

from, f o r

i n s t a n c e , e a s t e r n N o r t h A m e r i c a a n d t h e B r i t i s h I s l e s . A l t h o u g h no s u c c e s s i o n of f o r n a l l y d e f i n e d c o n o d o n t z o n e s h a s a s y e t b e e n e s t a b l i s h e d t h r o u g h o u t t h e s y s t e m , Cambrian c o n o d o n t s have c o n s i d e r a b l e p o t e n t i a l as g u i d e f o s s i l s , p a r t i c u l a r l y i n t h e U p p e r C a m b r i a n , w h e r e many forms show l i m i t e d v e r t i c a l r a n g e s a n d v e r y w i d e h o r i z o n t a l distributions. O r d o v i c i a n c o n o c b n t s , w h i c h i n c l u d e a b o u t 80 m u l t i e l e m e n t g e n e r a , a r e much b e t t e r known t h a n t h e C a m b r i a n o n e s , a n d show s t r i k i n g provincial d i f f e r e n t i a t i o n throughout

the period.

I n the North

A m e r i c a n M i d c o n t i n e n t P r o v i n c e , some 1 7 b i o s t r a t i g r a p h i c u n i t s of zonal t y p e have been recognized and i n t h e North A t l a n t i c Province, some 1 5 z o n e s ,

a n d more t h a n 10 s u b z o n e s , h a v e b e e n f o r m a l l y d e f i n e d .

Ordovician conodonts have proved very u s e f u l biDstratigrdphically,

in

many i n s t a n c e s p r o v i d i n g a s t r a t i g r a p h i c r e s o l u t i o n s u p e r i o r t o t h a t of any o t h e r f o s s i l group. S i l u r i a n c o n o d o n t f a u n a s e x h i b i t f a r less t a x o n o m i c d i v e r s i t y ( a b o u t 15 m u l t i e l e m e n t g e n e r a ) a n d p r o v i n c i a l d i f f e r e n t i a t i o n t h a n Ordovician ones.

T h e S i l u r i a n c o n o d o n t s u c c e s s i o n , b e s t known i n t h e

A t l a n t i c B o r d e r l a n d s from Great B r i t a i n , S c a n d i n a v i a , V i r g i n i a , a n d t h e e a s t e r n part

o f t h e North American M i d c o n t i n e n t , form t h e b a s i s

f o r a b o u t 1 2 z o n e s . Many of t h e s e z o n e s h a v e b e e n w i d e l y r e c o g n i z e d n o t o n l y i n Europe and North A m e r i c a

but also i n Australia,

Asia,

and n o r t h e r n Africa. A l t h o u g h p u b l i s h e d r e p o r t s on E a r l y P a l e o z o i c c o n o d o n t s of A f r i c a a n d S o u t h America i n c l u d e o n l y a f e w p a p e r s , t h e a v a i l a b l e

d a t a s u g g e s t t h a t t h e conodonts f a u n a s from t h o s e c o n t i n e n t s are, by and l a r g e ,

v e r y s i m i l a r t o t h o s e known f r o m t h e n o r t h e r n h e m i s p h e r e .

C o - o c c u r r e n c e of s t r a t i g r a p h i c a l l y d i a g n o s t i c c o n o d o n t s a n d

g r a p t o l i t e s h a s made i t p o s s i b l e t o t i e t o g e t h e r c o n o d o n t and g r a p t 3 l i t e z o n a l u n i t s i n t h e O rd o v i cian and S i l u r i a n a t a r e l a t i v e l y l a r g e

number o f s t r a t i g r a p h i c l e v e l s . G e o g r a p h i c d i s t a n c e a p p a r e n t l y was o f r e l a t i v e l y minor i m p o r t a n c e i n comparison w i t h e c o l o g i c f a c t o r s f o r t h e e s t a b l i s h m e n t of p a t t e r n s i n t h e E a r l y P a l e o z o i c conodont biogeography.

This conclu-

s i o n , a l o n g w i t h t h e f a c t t h a t v e r y similar c o n o d o n t f a u n a s were p r e s e n t on b o t h s i d e s o f t h e P r o t o - A t l a n t i c ,

make c o n o d o n t s o f l i t t l e

u s e f o r e v a l u a t i o n s o f t h e s i z e a n d d e v e l o p m e n t of c l i e P r o t o - A t l a n t i c Ocean, a t l e a s t a t t h e p r e s e n t t i m e .

------------INTRODUCTION

C o n o d o n t s a r e common m i c r o f o s s i l s i n many t y p e s o f Lower P a l e o z o i c m a r i n e r o c k s . Due t o t h e i r r a p i d e v o l u t i o n , t h e v e r y w i d e h o r i z o n t a l d i s t r i b u t i o n o f many t a x a , a n d t h e f a c t t h a t numerous s p e c i e s a p p a r e n t l y were n o t s t r o n g l y f a c i e s - c o n t r o l l e d ,

conodonts

now r a n k among t h e most u s e f u l f o s s i l s b i o s t r a t i g r a p h i c a l l y i n t h e

Lower P a l e o z o i c .

The g r o u p h a s b e e n known f o r 1 2 0 y e a r s b u t t h e

p e r i o d of modern a n d i n t e n s e s t u d y o f t h e s e f o s s i l s b e g a n a b o u t 1950 when t h e i r g r e a t b i o s t r a t i g r a p h i c p o t e n t i a l b e g a n t o b e a p p a r e n t . Since

then,

t h e c o n o d o n t l i t e r a t u r e h a s grown v e r y r a p i d l y a n d c l o s e

t o 100 p a p e r s ,

i n which

c o n o d o n t s a r e d e a l t w i t h i n o n e form o r a n -

o t h e r , a r e now p u b l i s h e d a n n u a l l y .

Most p a p e r s a r e of b i o s t r a t i -

g r a p h i c o r taxonomic n a t u r e b u t d u r i n g t h e l a s t f e w y e a r s ,

the paleo-

e c o l o g y and m i c r o m o r p h o l o g y o f t h e s e f o s s i l s h a v e a t t r a c t e d c o n s i d e r a b l e i n t e r e s t , and i t i s l i k e l y t h a t t h e s e areas of r e s e a r c h w i l l be increasingly important i n the future. Since t h e mid-l960's,

c o n o d o n t taxonomy h a s gone t h r o u g h a

p e r i o d of f u n d a m e n t a l change. d i f f e r e n t types

On t h e b a s i s o f t h e f a c t t h a t s e v e r a l

of c o n o d o n t e l e m e n t s e v i d e n t l y o c c u r r e d i n t h e

a p p a r a t u s of a s i n g l e i n d i v i d u a l ,

t h e taxonomy h a s

developed rapid-

l y f r o m a p u r e f o r m taxonomy b a s e d o n e x t e r n a l s h a p e o f s i n g l e e l e m e n t s , t o a z o o l o g i c a l l y more s o u n d m u l t i e l e m e n t taxonomy b a s e d on r e c o n s t r u c t e d a s s e m b l a g e s o f e l e m e n t s . A g r e a t many c o n o d o n t t a x a h a v e now b e e n r e - e v a l u a t e d

on a m u l t i e l e m e n t b a s i s b u t i t w i l l t a k e

a l o n g t i m e t o c o m p l e t e t h i s r a d i c a l t a x o n o m i c r e v i s i o n b e c a u s e many

h u n d r e d s p e c i e s and more t h a n 300 g e n e r a were o r i g i n a l l y p r o p o s e d

87 a s form t a x a . The p u r p o s e o f t h e p r e s e n t c o n t r i b u t i o n i s t o s u m m a r i z e b r i e f l y t h e conodont b i o s t r a t i s r a p h y s o f a r e s t a b l i s h e d f o r Cambrian t h r o u g h S i l u r i a n rocks i n t h e areas b o r d e r i n g t h e p r e s e n t A t l a n t i c . of geographic e x t e n t ,

I n terms

t h e area d e a l t w i t h i n c l u d e s S o r t h America e a s t

o f 90°w L o n g i t u d e , w e s t e r n and c e n t r a l E u r o p e , and t h e B a l t o s c a n d i c region.

B e c a u s e l i t t l e i s known a b o u t Lower P a l e o z o i c c o n o d o n t s i n

South A m e r i c a (see, f o r i n s t a n c e , S e r p a g l i ,

for i n s t a n c e , E t h i n g t o n a n d F u r n i s h ,

1 9 7 4 ) and A f r i c a (see,

1962), t h e review w i l l i n c l u d e

d a t a m a i n l y f r o m N o r t h A m e r i c a and E u r o p e . A l t h o u g h p u b l i s h e d s e v e r a l y e a r s a g o , and t h e r e f o r e o u t d a t e d i n some r e s p e c t s , a summary volume

e n t i t l e d "Symposium on Conodont B i o s t r a t i g r a p h y " eds.,

(Sweet and Bergstrbm,

1 9 7 1 ) s t i l l p r o v i d e s a u s e f u l summary o f Lower P a l e o z o i c c o n o -

dont b i o s t r a t i g r a p h y ,

a n d t h e r e a d e r is r e f e r r e d t o t h a t volume f o r

a more d e t a i l e d t r e a t m e n t t h a n i s p o s s i b l e w i t h i n t h e s c o p e o f t h e present contribution.

P a p e r s i n t h a t volume a l s o g i v e i l l u s t r a t i o n s

of many of t h e s t r a t i g r a p h i c a l l y i m p o r t a n t c o n o d o n t s m e n t i o n e d b e l o w .

CAMBRIAR

The o l d e s t c o n o d o n t s known a r e f r o m s t r a t a i n S i b e r i a c u r r e n t l y c l a s s i f i e d as l a t e Precambrian (Missarzhevsky, Missarzhevsky,

1 9 7 3 ; Matthews a n d

1 9 7 5 ) b u t t h e g r o u p , w h i c h i s r e p r e s e n t e d by s p e c i e s

of t h e o r d e r P a r a c o n o d o n t i d a ,

exhibited l i t t l e d i v e r s i t y before Late

Cambrian time. The p a r a c o n o d o n t s a r e w e a k l y p h o s p h a t i z e d a n d d i f f e r a l s o i n o t h e r r e s p e c t s from t h e co n o d o n t i f or m c o n o d o n t s , which i n c l u d e p r a c t i c a l l y a l l post-Cambrian forms. A l t h o u g h known f r o m t h e B a l t o s c a n d i c area ( M C l l e r ,

1959; Poul-

s e n , 1 9 6 6 ; B e n g t s s o n , 1 9 7 6 ) , Germany (Mfiller, 1 9 5 9 , e r r a t i c b o u l d e r s ) , Poland ( S z a n i a w s k i , 1 9 7 1 ) , t h e B r i t i s h Isles (Miller and Rushton, 1 9 7 3 ) , a n d N e w York S t a t e ( L a n d i n g , 1 9 7 4 b , 1 9 7 6 ) , C a m b r i a n c o n o d o n t s are s t i l l v e r y l i t t l e s t u d i e d i n t h e A t l a n t i c B o r d e r l a n d s ( F i g . 1 ) . T h e i r p o t e n t i a l as b i o s t r a t i g r a p h i c t o o l s was s u g g e s t e d i n t h e p i o n e e r work by M g l l e r

( 1 9 5 9 ) , b u t s t u d i e s on Cambrian c o n o d o n t

b i o s t r a t i g r a p h y have s o f a r b een co n cerned o n l y w i t h m ai nl y L a t e Cambrian s u c c e s s i o n s i n a r e a s s u c h a s w e s t e r n N o r t h America ( M i l l e r , 1 9 7 5 ) , I r a n (Mcller, 1 9 7 3 ) , Q u e e n s l a n d ( D r u c e a n d J o n e s ,

1 9 7 1 ) , and

C h i n a (Nogami, 1 9 6 6 , 1 9 6 7 ) . Mcller ( 1 9 7 3 ) a n d Miller ( 1 9 7 5 ) i n t r o -

88

2oi

W Spitsbergen

w

10

D

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I

N Scotland

3

PRO TO-ATLANTIC OCEAN

20 E Spltsbergen

F i g . 1 . Cambrian conodont o c c u r r e n c e s i n N o r t h A m e r i c a and n o r t h w e s t e r n Europe p l o t t e d on a s k e t c h - m a p s h o w i n g i n f e r r e d c o n t i n e n t p o s i t i o n s d u r i n g M i d d l e Cambrian t i m e . A s i n F i g . 2 a n d 4, e a c h d o t d e n o t e s one o r s e v e r a l conodont l o c a l i t i e s which have p r o d u c e d c o l l e c t i o n s d e s c r i b e d i n t h e l i t e r a t u r e o r s e e n by t h e w r i t e r . L a t i t u d i n a l p o s i t i o n of n o r t h w e s t e r n E u r o p e b a s e d on K o l t i m i e r and B e r g s t r h ( i n p r e p a r a t i o n ) .

d u c e d z o n a l u n i t s b a s e d on Late Cambrian species a n d t h e r e a r e i n d i c a t i o n s t h a t a t l e a s t some of t h e s e z o n e s a r e r e c o g n i z e a b l e i n t h e Appalachians

( L a n d i n g , 1 9 7 6 ) . N o a t t e m p t h a s b e e n made s o f a r t o

e s t a b l i s h f o r m a l c o n o d o n t b i o s t r a t i g r a p h i c u n i t s i n t h e Lower a n d M i d d l e C a m b r i a n a n d a p a r t f r o m a f e w p a p e r s ( L a n d i n g , 197413; P o u l s e n , 1 9 6 6 ; B e n g t s s o n , 1976), c o n o d o n t s o f t h a t a g e r e m a i n v i r t u a l l y un-

s t u d i e d i n t h e A t l a n t i c area.

The known Cambrian c o n o d o n t f a u n a s i n -

c l u d e some 1 5 g e n e r a of s i m p l e f o r m s s u c h a s F u r n i s h i n a ,

",

Prosagittodontus,

Muellerina, Hertzina,

Proconodon-

Prooneotodus,

P r o s c a n d o d u s a n d h a v e a somewhat monotonous c h a r a c t e r .

and

However,

there

a r e c l e a r i n d i c a t i o n s t h a t some s p e c i e s h a v e a w i d e g e o g r a p h i c d i s t r i b u t i o n combined w i t h a r e a s o n a b l y s h o r t v e r t i c a l r a n g e ; accor di n g l y , a p r o m i s i n g and c h a l l e n g i n g t a s k would b e t o e x p l o r e t h e i r

89 W Spitsbergen

N . Ireland

0 0 0

PROTO-ATLANTIC OCEAN ? E\

N e w Brunswick

Nova Scotia \

Fig.2. Ordovician conodont occurrences i n North America and northwestern Europe plotted on a sketch-map showing inferred positions of continents in Early Ordovician (Arenigian) time. Latitudinal position of Europe according to Noltimier and Bergstram (1976; in preparation), that of North America based on McElhinny and Opdyke (1973). Dark dots denote North Atlantic Province faunas, open circles Midcontinent Province faunas. Note the presence of North Atlantic Province conodont faunas in the eastern Appalachians and in California (Klamath Mountains). utility as regionally useful index fossils in the Atlantic area.

ORDOVICIAN

The Early and Middle Ordovician was a time of rapid conodont evolution that led to a diversification at the generic and specific

90 l e v e l t h a t i s a p p a r e n t l y g r e a t e r than t h a t of any other comparable t i m e i n t e r v a l i n t h e s t r a t i g r a p h i c record o f conodonts.

This is i l l u s -

t r a t e d by t h e f a c t t h a t some 150 f o r m g e n e r a o f c o n o d o n t s h a v e b e e n p r o p o s e d on t h e b a s i s of O r d o v i c i a n c o l l e c t i o n s a n d more t h a n h a l f of t h e s e a r e d i s t i n c t as m u l t i e l e m e n t g e n e r a .

In a d d i t i o n , t h e r e a r e

q u i t e a f e w c h a r a c t e r i s t i c , b u t s t i l l unnamed,

g e n e r a , and t h e t o t a l

number o f O r d o v i c i a n m u l t i e l e m e n t g e n e r a may u l t i m a t e l y p r o v e t o b e

w e l l i n e x c e s s o f 100. T h i s f i g u r e i s more t h a n t w i c e as h i g h a s t h a t f o r any o t h e r g e o l o g i c p e r i o d . O r d o v i c i a n conodonts h a v e b e e n f a r more i n t e n s e l y s t u d i e d t h a n t h e Cambrian o n e s i n t h e A t l a n t i c B o r d e r l a n d s b u t t h e r e a r e , n e v e r t h e -

l e s s , l a r g e g a p s i n o u r k n o w l e d g e a b o u t f a u n a s of t h a t a g e .

Best

known a r e f a u n a s f r o m t h e B a l t o s c a n d i c a r e a a n d t h e N o r t h A m e r i c a n Midcontinent b u t t h o s e from s e v e r a l o t h e r major r e g i o n s ,

f o r instance,

S o u t h America, n o r t h e r n A f r i c a , and G r e e n l a n d , r e m a i n v i r t u a l l y unexplored.

Fig.2 g i v e s t h e g e n e r a l geographic l o c a t i o n of important

Ordovician conodont o c c u r r e n c e s i n areas b o r d e r i n g t h e p r e s e n t North Atlantic. Taken as a w h o l e , O r d o v i c i a n c o n o d o n t f a u n a s p r o b a b l y e x h i b i t a s t r o n g e r biogeographic d i f f e r e n t i a t i o n than t h o s e of any o t h e r system (Bergstram,

1 9 7 3 a ; B a r n e s e t a l . , 1 9 7 3 ; Sweet and B e r g s t r a m , 1 9 7 4 ) .

This f a u n a l provincialism,

which c a n b e t r a c e d b a c k t o t h e Tremadoc-

i a n , p r e v a i l e d to t h e end of t h e p e r i o d a l t h o u g h modified as t o a r e a l e x t e n t and d i s t i n c t i v e n e s s . recognized,

The two main f a u n a l p r o v i n c e s g e n e r a l l y

t h e North A m e r i c a n M i d c o n t i n e n t P r o v i n c e and t h e N o r t h

A t l a n t i c P r o v i n c e , a r e c h a r a c t e r i z e d b y two c o n o d o n t f a u n a s s o d i f f e r e n t t h a t s e p a r a t e z o n a l schemes have been e s t a b l i s h e d f o r e a c h o f them ( S w e e t e t a l . ,

1971; E t h i n g t o n and C l a r k ,

1971; Bergstram,

1 9 7 1 a , 1 9 7 1 b ; L i n d s t r B m , 1 9 7 1 ) and t h e r e i s s t i l l c o n s i d e r a b l e unc e r t a i n t y regarding t h e p r e c i s e r e l a t i o n s between s e v e r a l u n i t s i n t h e s e schemes. A p r o v i s i o n a l c o r r e l a t i o n between t h e s e p r o v i n c i a l schemes i s g i v e n i n F ig . 3 .

North American M i d c o n t i n e n t P r o v i n c e

Lower O r d o v i c i a n ( C a n a d i a n ) c o n o d o n t f a u n a s i n t h i s p r o v i n c e , w h i c h o c c u p i e s t h e c e n t r a l p o r t i o n o f t h e N o r t h A m e r i c a n c o n t i n e n t as w e l l a s p a r t s of S i b e r i a a n d A u s t r a l i a , are c h a r a c t e r i z e d by " s i m p l e -

cone" g e n e r a s u c h as Acanthodus, Scolopodus, U l r i c h o d i n a , Oneotodus,

91 IIDCONTINENT I A M G BRITAIN EALTOSCANDIE

‘ z

ASHGlLLlAN

5 -z

a I

LLANDEILIAN

4

3

1-I

HARJUAN

10

CARADOCIAN

Z

UJNAS

NORTH ATLANTIC CONODONT

ZONES

I

SUEZONES

Amorphognathus ordovicfcus

NOT YET DISTINGUISHED Amorphognathus superbus

Arnorphognathus tvaerensfs

1

Prfoniodus alobarus Prioniodus gerdae

Pygodus ansennus

VIRUAN

’

1

?

i

Eoplacognarhus robusrus

Pygodus serrus

I

Eoplacognarhus reclfnarus

I

Eoplacognarhus fohaceus

0

- ?

b

LLANVIRNIAN

UNNAMED

Eoolacoonarhus suecfcus

Eoplacognarhus variabilis 4

3

Mfcrozarkodina parva Paroistodus originalis Prioniodus navis

7-

ARENIGIAN

z 9

OELANDIAN

NOT YET DISTINGUISHED

?

2

5

TREMADOCIAN

Fig.3. C o r r e l a t i o n between S o r t h American and European Ordovician standard series, Midcontinent Province conodont f a u n a s (Sweet e t a l . , 1971; Ethington and C l a r k , 1 9 7 1 ) , and S o r t h A t l a n t i c Province conodont zones and subzones (Lindstrcm, 1971; B e r g s t r h , 1 9 7 1 a , 1 9 7 1 b ) . A s shown in t h e d i a g r a m , t h e s t r a t i g r a p h i c s c o p e of t h e t h r e e m a i n s u b d i v i s i o n s o f t h e O r d o v i c i a n i s , by t r a d i t i o n , n o t t h e same i n E u r o p e a n d N o r t h America; i n t h e t e x t b e l o w , t h e terms L o w e r , M i d d l e , a n d Upper O r d o v i c i a n a r e u s e d i n t h e i r l o c a l s e n s e , t h a t i s , t o d e n o t e t h e Oelandian, Viruan, and H a r j u a n i n Europe, and t h e Canadian, Champlainian, and C i n c i n n a t i a n i n N o r t h A m e r i c a . Top o f C a n a d i a n i s t a k e n a s t h e b a s e o f t h e W h i t e r o c k i a n S t a g e . A s t o t h e un-named i n t e r v a l s b e t w e e n t h e T r e m a d o c i a n / A r e n i g i a n a n d t h e L l a n v i r n i a d L l a n d e i l i a n , see Bergstrom e t a l . (1973, 1 9 7 4 ) . “ P a l t o d u s f ‘ , a n d o t h e r s . Compound-element g e n e r a are less w e l l repres e n t e d b u t i n c l u d e Cordylodus, Loxodus, Chosonodina,

and Oepikodus.

A l t h o u g h e a r l i e s t O r d o v i c i a n f a u n a s b e g i n t o b e w e l l known

1969; D r u c e a n d J o n e s ,

(Miller,

1 9 7 1 ) much r e m a i n s t o b e l e a r n e d a b o u t y o u n g e r

E a r l y O r d o v i c i a n c o n o d o n t f a u n a s of t h i s p r o v i n c e .

Fortunately,

this

s e r i o u s gap i n o u r k n o w l e d g e may b e a t l e a s t p a r t i a l l y f i l l e d b y new d a t a f r o m s t i l l l a r g e l y u n p u b l i s h e d s t u d i e s i n h’ew S l e x i c o - T e x a s ( R e p e t s k i , 1974) a n d Oklahoma

(Mound, 1 9 6 8 ; B r a n d ,

1 9 7 6 ; P o t t e r , 1975).

92 C o r r e s p o n d i n g work i n A s i a i s b e i n g c a r r i e d o u t b y , among o t h e r s , Lee ( 1970, 1975 )

.

D e s c r i p t i o n s o f e a r l i e s t Middle O r d o v i c i a n ( e a r l i e s t Champlaini a n ) Midcontinent Province conodont f a u n a s remain l a r g e l y unpublished i n N o r t h America b u t t h e a v a i l a b l e p u b l i s h e d a n d u n p u b l i s h e d d a t a

( s e e , f o r i n s t a n c e , Mound, 1 9 6 5 ; Bradshaw, 1 9 6 9 ) show t h a t M i d c o n t i n e n t f a u n a s of t h i s a g e i n c l u d e , a p a r t f r o n a n a r r a y o f " s i m p l e - c o n e " g e n e r a s u c h as D r e p a n o i s t o d u s , P a n d e r o d u s , O i s t o d u s , a n d S c o l o p o d u s , a d i s t i n c t i v e s u i t e o f compound-element

genera, f o r instance, Multi-

oistodus, Leptochirognathus, Histiodella, d u s , and T r i c l a d i o d u s . -

Bergstroemognathus

,

Erismo-

Typical p l a t f o r m elements are rare o r missing

i n most f a u n a s of t h i s t y p e , b u t o c c u r ( P o l y p l a c o g n a t h u s , S c y p h i o d u s ) i n s l i g h t l y y o u n g e r M i d d l e O r d o v i c i a n f a u n a s a l o n g w i t h a b u n d a n t rep r e s e n t a t i v e s o f Phragmodus,

Plectodina,

and f i b r o u s c o n o d o n t g e n e r a

s u c h a s C u r t o g n a t h u s , C h i r o g n a t h u s , a n d C o l e o d u s ( B e r g s t r h a n d Sweet, 1966 ; S c h o p f , 1966 ; W e b e r s ,

1966 ).

U n f o r t u n a t e l y , nowhere i n t h e

North American M i d c o n t i n e n t i s t h e r e a r e a s o n a b l y c o m p l e t e Middle O r d o v i c i a n ( C h a m p l a i n i a n ) s u c c e s s i o n and t h e s e q u e n c e of f a u n a s p r o p o s e d by S w e e t e t a l .

( 1 9 7 1 ) is p i e c e d t o g e t h e r f r o m s e c t i o n s i n

s e v e r a l d i f f e r e n t areas. Although t h e p r e c i s e c o r r e l a t i o n between some u n i t s i n t h e s e a r e a s is s t i l l u n c e r t a i n , t h e g e n e r a l s u c c e s s i o n o f u n i t s i n t h i s scheme h a s p r o v e d t o b e v e r y u s e f u l r e g i o n a l l y o v e r t h e N o r t h A m e r i c a n c r a t o n ( S w e e t and B e r g s t r a m ,

i n press).

A t p r e s e n t t h e b e s t known L a t e O r d o v i c i a n ( C i n c i n n a t i a n ) c o n o -

dorit f a u n a l s u c c e s s i o n i n N o r t h A m e r i c a i s t h a t o f t h e C i n c i n n a t i a r c h a r e a i n O h i o a n d a d j a c e n t s t a t e s ( S w e e t , i n p r e s s ) . The L a t e O r d o v i c i a n f a u n a s t h e r e i n c l u d e r e p r e s e n t a t i v e s o f , among o t h e r s , A p h e l o g n a t h u s , B e l o d i n a , O u l o d u s , Phragmodus, dognathus.

I n some i n t e r v a l s ,

t a t i v e s of Amorphognathus,

Plectodina,

and R h i p i -

t h e r e are a l s o o c c u r r e n c e s o f r e p r e s e n -

I c r i o d e l l a , Periodon,

Protopanderodus,and

Rhodesognathus, which are g e n e r a l l y tak e n t o b e b a s i c a l l y Nor t h A t l a n t i c P r o v i n c e f o r m s . Some o f t h e s e are i m p o r t a n t s t r a t i g r a p h i c a l l y and s e r v e as c o r r e l a t i v e l i n k s w i t h t h e North A t l a n t i c conodont

z o n a l s u c c e s s i o n , w h e r e t h e y a r e f a r more w i d e l y d i s t r i b u t e d .

By a n d

l a r g e , t h e i n d i g e n o u s C i n c i n n a t i a n c o n o d o n t f a u n a s a r e of a r a t h e r monotonous a n d c o n s e r v a t i v e t y p e and t h e y are n o t n o t e d f o r s h o w i n g conspicuous e v o l u t i o n a r y changes through t h e sequence.

In t h e C i n c i n n a t i r e g i o n , as w e l l a s e l s e w h e r e i n e a s t e r n USA, t h e i n t e r v a l w i t h i n which t h e O r d o v i c i a n / S i l u r i a n boundary f a l l s

is

93 marked b y a s t r i k i n g c h a n g e i n t h e c o m p o s i t i o n o f t h e c o n o d o n t faunas.

A m a j o r i t y of t h e t y p i c a l M i d c o n t i n e n t p r o v i n c e g e n e r a a p p a r -

e n t l y became e x t i n c t i n l a t e s t O r d o v i c i a n t i m e a n d o n l y P a n d e r o d u s and a f e w o t h e r " s i m p l e - c o n e " Amorphognathus,

Icriodella,

g e n e r a , as w e l l a s r e p r e s e n t a t i v e s o f

O u l o d u s , and a f e w o t h e r c o m p o u n d - e l e m e n t

genera, survived i n t o S i l u r i a n t i m e .

Accordingly, S i l u r i a n conodont

f a u n a s d i f f e r a good d e a l f r o m O r d o v i c i a n o n e s a n d t h e g e n e r a l e x t i n c t i o n o f c o n o d o n t g e n e r a i n Late O r d o v i c i a n time i s one o f t h e most s e v e r e d u r i n g t h e e n t i r e t i m e o f e x i s t e n c e o f t h e g r o u p .

The N o r t h A t l a n t i c P r o v i n c e

Early Ordovician

(Oelandian) conodont f a u n a s of t h e North Atlan-

t i c P r o v i n c e a r e c u r r e n t l y b e s t known f r o m t h e B a l t o s c a n d i c a r e a ( L i n d s t r c m , 1955, 1960, 1971; S e r g e e v a , 1964; V i i r a , Kohut,

1972; van W a m e l ,

d e s c r i b e d f r o m S c o t l a n d (Lamont a n d L i n d s t r g m ,

America ( F $ h r a e u s ,

1967, 1975;

1 9 7 4 ) a l t h o u g h a few c o l l e c t i o n s h a v e b e e n

1970; Bergstram e t a l . ,

1957), e a s t e r n Korth

1972; Landing,

1974a),

and A r g e n t i n a ( S e r p a g l i , 1 9 7 4 ) . E a r l y O r d o v i c i a n f a u n a s o f t h i s p r o vince are c h a r a c t e r i z e d by a wide v a r i e t y of such as Drepanodus, A co n ti o d u s ,

Paroistodus,

Protopanderodus,

"simple-cone"

Drepanoistodus,

Oistodus,

genera Paltodus,

S c a n d o d u s , and S t o l o d u s a s w e l l a s

compound-element g e n e r a s u c h a s C o r d y l o d u s , M i c r o z a r k o d i n a , and P e r i o d o n .

Oepikodus,

It is of i n t e r e s t t o n o t e t h a t t r u e platform conodonts

a p p e a r e d as e a r l y a s i n e a r l i e s t O r d o v i c i a n ( T r e m a d o c i a n ) t i m e i n t h e B a l t o s c a n d i c area ( L i n d s t r B m , 1 9 5 5 ) b u t s u c h c o n o d o n t s d i d n o t c o n s t i t u t e a s u b s t a n t i a l p a r t of the conodont f a u n a s u n t i l Middle Ordovician (Viruan) t i m e .

S u c c e s s i o n s o f c o n o d o n t z o n e s p r o p o s e d by

S e r g e e v a ( 1 9 6 4 ) , L i n d s t r b ( 1 9 7 1 ) , a n d V i i r a ( 1 9 7 5 ) , among o t h e r s , d i f f e r r e l a t i v e l y l i t t l e f r o m e a c h o t h e r a n d t h e one i n t r o d u c e d by Lindstrbm (1971) has proved t o be widely a p p l i c a b l e .

Van Wamel ( 1 9 7 4

p r o p o s e d a f a r more d e t a i l e d z o n a l s u b d i v i s i o n o f T r e m a d o c i a n a n d E a r l y A r e n i g i a n s t r a t a i n e a s t e r n Sweden b u t some o f h i s 2 0 assemb l a g e z o n e s , w h i c h were b a s e d on s i n g l e s a m p l e s , may b e o n l y o f l o c a b i o s t r a t i g r a p h i c s i g n i f i c a n c e , i f any. Lindstram's

On t h e o t h e r h a n d , u n i t s of

( 1 9 7 1 ) z o n a l s u c c e s s i o n have been r e c o g n i z e d i n areas as

f a r a p a r t a s N e w f o u n d l a n d , Texas, Nevada, and A r g e n t i n a , a n d i t i s c l e a r t h a t conodonts r i v a l g r a p t o l i t e s as t h e b i o s t r a t i g r a p h i c a l l y most u s e f u l f o s s i l g r o u p i n t h e Lower O r d o v i c i a n o f t h i s p r o v i n c e .

94 In t h e North A t l a n t i c P r o v i n c e , Middle Ordovician ( V i r u a n ) c o n o d o n t s a r e b e s t known f r o m t h e B a l t o s c a n d i c a r e a ( B e r g s t r B m , 1971a, 1971b; H a m a r ,

1964, 1966; Lindstram,

1960; V i i r a ,

1962,

1975) and

e a s t e r n S o r t h America ( B e r g s t r 6 m , 1 9 7 1 a , 1 9 7 3 c ; B e r g s t r b e t a l . , 1974; Bergstrijm and C a r n e s ,

i n p r e s s ; Fahraeus, 1970, 1973; Sweet

a n d I i e r g s t r B m , 1 9 6 2 ) b u t some u n i t s i n Great B r i t a i n (Lamont a n d L i n d s t r h , 1957; Lindstrom,

1 9 5 9 ; B e r g s t r a m , 1 9 6 4 , 1 9 7 1 a ; Rhodes,

1951) and France (Lindstrhm e t a l . ,

1974) have a l s o y i e l d e d conodonts

of t h i s a g e . Z o n a l u n i t s h a v e b e e n p r o p o s e d by B e r g s t r z m ( 1 9 7 1 a ) a n d V i i r a ( 1 9 7 5 ) a n d many o f t h e u n i t s i n t h e f o r m e r ' s z o n a l s u c c e s s i o n

have been r e c o g n i z e d r e g i o n a l l y i n t h e North A t l a n t i c P r o v i n c e . Rliddle O r d o v i c i a n c o n o d o n t f a u n a s o f t h i s a r e a a r e c h a r a c t e r i z e d by a s u c c e s s i o n of s t r a t i g r a p h i c a l l y i m p o r t a n t s p e c i e s of Amorphognathus, E o p l a c o g n a t h u s , P r i o n i o d u s ( B a l t o n i o d u s ) , a n d P y g o d u s as w e l l a s by t h e w i d e s p r e a d p r e s e n c e of P e r i o d o n a n d " s i m p l e - c o n e " Protopanderodus.

genera such as

R e p r e s e n t a t i v e s of I c r i o d e l l a , a l t h o u g h r a t h e r

common i n B r i t i s h f a u n a s , a r e r a r e i n B a l t o s c a n d i a b u t known a l s o f r o m t h e A p p a l a c h i a n s ; i t s h o u l d be n o t e d , h o w e v e r , t h a t t y p i c a l Korth A t l a n t i c P r o v i n c e f a u n a s o f l a t e Middle O r d o v i c i a n a g e are c u r r e n t l y n o t known f r o m t h e A p p a l a c h i a n s . L a t e Ordovician ( H a r j u a n ) f a u n a s of North A t l a n t i c Province

ts'pe a r e as y e t n o t d o c u m e n t e d i n e a s t e r n N o r t h America, b u t a r e known f r o m s e v e r a l a r e a s i n E u r o p e , strbm,

1971a; V i i r a ,

including Ealtoscandia (Berg-

1 9 7 5 ) , Great B r i t a i n ( R h o d e s , 1 9 5 5 ; B e r g s t r a m ,

1964, 1 9 7 1 a ) , t h e C a r n i c Alps i n I t a l y and A u s t r i a ( S e r p a g l i , 1967; SchBnlaub, 1 9 7 1 ) , T h u r i n g i a (KnGpfer, 1 9 6 7 ) , and S p a i n ( F u g a n t i and S e r p a g l i , 1 9 6 8 ) . The b i o s t r a t i g r a p h i c z o n a t i o n o f t h e Upper O r d o v i c i a n b a s e d on c o n o d o n t s i s s t i l l p r e l i m i n a r y ( B e r g s t r a m , 1 9 7 1 a ) a n d some r e f i n e m e n t w i l l n o d o u b t b e p o s s i b l e when t h e p e r t i n e n t f a u n a s a r e b e t t e r known t h a n a t t h e p r e s e n t t i m e .

Sorth Atlantic Province

f a u n a s of t h i s a g e a r e less v a r i e d t h a n f a u n a s from o l d e r p a r t s o f t h e s y s t e m ; comnon a n d w i d e s p r e a d e l e m e n t s i n c l u d e A m o r p h o g n a t h u s , D a p s i l o d d s , Hamarodus, P e r i o d o n , G t o p a n d e r o d u s , P r i o n i o d u s , a n d Strachanoynathus wnereas forms o f I c r i o d e l l a , D i c h o d e l l a , and Nordiod u s h a v e a more l i m i t e d d i s t r i b u t i o n . A s i s a l s o t h e c a s e i n t h e

_-

Nidcontinent Province, the i n t e r v a l near the Ordovician/Silurian b o u n d a r y i s marked b y a d r a s t i c e x t i n c t i o n of common a n d w i d e s p r e a d Uorth A t l a n t i c P r o v i n c e t a x a ; o n l y Amorphognathus, H i n d e o d e l l a ( O z a r k o d i n a ) , and I c r i o d e l l a , a l o n g w i t h sosne " s i m p l e - c o n e " g e n e r a ,

95 survived i n t o t h e S i l u r i a n .

I t s h o u l d be n o t e d , however, t h a t e a r l i -

est S i l u r i a n ( e a r l y L l a n d o v e r i a n ) conodonts are v i r t u a l l y

unknown i n

t h e a r e a u n d e r d i s c u s s i o n a n d t h i s may make t h e e x t i n c t i o n seem more a b r u p t t h a n i s r e a l l y t h e case.

Interestingly, the extinction appears

t o have a f f e c t e d t r o p i c a l - s u b t r o p i c a l

( M i d c o n t i n e n t ) f a u n a s as w e l l

a s temperate (North A t l a n t i c ) faunas e q u a l l y severely. Accordingly, t h e c a u s e may n o t be s o l e l y a s h a r p d r o p i n water t e m p e r a t u r e a s s o c i a t e d with t h e Late Ordovician g l a c i a t i o n . I t

may b e s i g n i f i c a n t t h a t

t h e g e n e r a s u r v i v i n g i n t o t h e S i l u r i a n were a l l among t h e more w i d e l y d i s t r i b u t e d , a n d t h o s e n o t r e s t r i c t e d t o one p r o v i n c e , d u r i n g t h e O r d o v i c i a n w h i c h s u g g e s t s t h a t t h e s e c o n o d o n t s had t h e c a p a c i t y t o adapt t o a r e l a t i v e l y wide range of environmental c o n d i t i o n s .

SILURIAN

In comparison w i t h t h o s e from t h e Ordovician, S i l u r i a n conod o n t s a r e l e s s w e l l known r e g i o n a l l y i n t h e A t l a n t i c B o r d e r l a n d s , A l s o , p r a c t i c a l l y n o t h i n g h a s b e e n p u b l i s h e d on c o n o d o n t f a u n a s f r o m t h e v e r y l o w e r m o s t p a r t o f t h e s y s t e m . However, j u d g i n g f r o m d a t a c u r r e n t l y a v a i l a b l e , t h e M i d d l e ( W e n l o c k i a n ) a n d Upper ( L u d l o v i a n and P r i d o l i a n ) S i l u r i a n c o n o d o n t s a r e now r e l a t i v e l y w e l l known a s f a r as t h e i r g e n e r a l taxonomy a n d s t r a t i g r a p h i c r a n g e s a r e c o n c e r n e d . A c o n o d o n t - b a s e d z o n a l s c h e m e f o r most o f t h e S i l u r i a n S y s t e m

was i n t r o d u c e d by W a l l i s e r ( 1 9 6 4 ) . I t i s b a s e d l a r g e l y on t h e C e l l o n s e c t i o n i n t h e C a r n i c A l p s o f A u s t r i a . With some m o d i f i c a t i o n s , e s p e c i a l l y i n t h e L l a n d o v e r i a n , Walliser's z o n a l system has proved a p p l i c a b l e world-wide.

The z o n a l s c h e m e s c u r r e n t l y i n u s e i n E u r o p e

and N o r t h A m e r i c a i n c l u d e a b o u t 1 2 a s s e m b l a g e z o n e s ; a c c o r d i n g l y , t h e y a r e l e s s d e t a i l e d t h a n t h a t b a s e d on g r a p t o l i t e s , w h i c h i n c l u d e s a b o u t 32 z o n e s ( B u l m a n , 1 9 7 0 ) .

I n t h e a r e a u n d e r d i s c u s s i o n , S i l u r i a n c o n o d o n t s a r e b e s t known from G r e a t B r i t a i n ( A l d r i d g e , 1 9 7 2 , 1 9 7 5 ) , s o u t h e r n a n d e a s t e r n Sweden ( J e p p s s o n , 1 9 7 5 ) , c e n t r a l E u r o p e (Walliser, 1 9 6 4 ; S c h d n l a u b , 1 9 7 1 ; Walmsley e t a l . ,

1974), Virginia

( H e l f r i c h , 1 9 7 5 ) , and t h e

e a s t e r n M i d c o n t i n e n t o f N o r t h America ( C o o p e r , 1 9 7 5 ; N i c o l l a n d Rexroad, 1968; P o l l o c k and Rexroad, 1973; Rexroad, 1967; Rexroad and Nicoll,

1 9 7 1 ) . S i l u r i a n c o n o d o n s a r e a l S o known f r o m N o r t h A f r i c a

( E t h i n g t o n and F u r n i s h , 1 9 6 2 ) , e a s t e r n Canada ( L e g a u l t , 1 9 6 8 ) , t h e

30 -

-0

J

I

20-

30i

SILURIAN

L

I

F i g . 4 . S i l u r i a n conodont o c c u r r e n c e s i n N o r t h America and n o r t h w e s t e r n Europe p l o t t e d on a s k e t c h - m a p s h o w i n g i n f e r r e d p o s i t i o n o f c o n t i n e n t s i n E a r l y S i l u r i a n ( L l a n d o v e r i a n ) t i m e . Note t h a t p r a c t i c a l l y a l l t h e s e conodont f a u n a s f a l l w i t h i n a b e l t between 2 0 d e g r e e s S o u t h and North l a t i t u d e . I b e r i a n P e n i n s u l a ( K o c k e l , 1958; v a n d e n B o o g a a r d ,

1965), France

( F e i s t a n d S c h B n l a u b , 1 9 7 4 ) and s c a t t e r e d l o c a l i t i e s i n a f e w o t h e r

areas i n t h e A t l a n t i c B o r d e r l a n d s . A r e v i e w of S i l u r i a n c o n o d o n t o c c u r r e n c e s i n t h e A t l a n t i c B o r d e r l a n d s i n N o r t h America a n d n o r t h e r n Europe i s g i v e n i n F i g . 4 . S i l u r i a n conodont f a u n a s ,

a s now known, i n c l u d e 15-20 r n u l t i e l e -

ment g e n e r a and a r e f a r l e s s v a r i e d a t b o t h t h e g e n e r i c a n d s p e c i f i c l e v e l t h a n t h e O r d o v i c i a n o n e s . F u r t h e r , t h e y d o n o t show a n y s t r i k i n g b i o g e o g r a p h l c d i f f e r e n t i a t i o n a l t h o u g h t h e r e a r e some regional d i f f e r e n c e s i n t h e s p e c i f i c composition of t h e faunas

(Jeppsson, 1 9 7 5 ) . Zarliest S i l u r i a n ( e a r l y L l a n d o v e r i a n ) conodonts are as y e t v i r t u a l l y unknown b u t y o u n g e r L l a n d o v e r i a n f a u n a s a r e c h a r a c t e r i z e d by A p s i d o g n a t h u s ,

Carniodus, Distomodus, I c r i o d e l l a , Llandovery-

g n a t h u s , H i n d e o d e l l a ( = O z a r k o d i n a ) , I c r i o d i n a , and Hadrognathus.

The

c o n s i d e r a b l e number o f p l a t f o r m g e n e r a i n t h e L l a n d o v e r i a n f a u n a s i s a n o t a b l e f e a t u r e ; i n younger S i l u r i a n f a u n a s , p l a t f o r m conodont s a r e uncommon a n d l i t t l e v a r i e d , L l a n d o v e r i a n s t r a t a , a s w e l l a s younger S i l u r i a n b e d s , c o n t a i n s e v e r a l wi despr ead

"simple-cone"

97 CONODONT ZONES

SERIES

CARNIC ALPS

PRlDOLlAN

H s

GREAT BRITAIN

H

eosieinhornensis

S

eosreinhornensis

NORTH AMEPICA

H s eosreinhornensis

H crispa / laria/aius

H crispa I laiialaius

LUDLOVIAN

P sr1uricus

i

NOT YET IDENTIFIED

P si/uricus

H sagitia

H sagiiia

NOT YET IDENTIFIED P amorphognarhoides

p amorphognathoides

A ploeckensis H crassa

H segiiia WENLOCKIAN I

K peiule P amorphognathoides

~

P celloni

LLANDOVERIAN

7

/ inconsfans H sieurognarhoides

?

/ discrete

Bereich 1

I deflecia

NOT YET IDENTIFIED

P celloni / irregularis P simplex

?

F i g . 5 . S i l u r i a n c o n o d o n t z o n e s i n E u r o p e a n d K o r t h America. N o t e t h a t t h e p r e c i s e c o r r e l a t i o n b e t w e e n some u n i t s i s s o m e w h a t u n c e r t a i n , p a r t i c u l a r l y i n t h e Lower a n d M i d d l e L l a n d o v e r i a n . g e n e r a b u t t h e s e a r e of m i n o r s i g n i f i c a n c e b i o s t r a t i g r a p h i c a l l y ,

at

l e a s t as f a r a s our p r e s e n t k n o w l e d g e g o e s , Wenlockian and younger S i l u r i a n f a u n a s are dominated by numerous species of Hindeodella

(=Ozarkodina) and Ligonodina b u t s t r a t i g r a p h i -

c a l l y i m p o r t a n t forms o f t h e p l a t f o r m g e n e r a K o c k e l e l l a ,

Pelekys-

g n a t h u s , a n d P o l y g n a t h o i d e s a r e p r e s e n t i n s o m e i n t e r v a l s . A compreh e n s i v e a n d a u t h o r a t i v e r e v i e w e s p e c i a l l y of E u r o p e a n L a t e S i l u r i a n faunas has been given r e c e n t l y by Jeppsson

(1975) a n d a n e x c e l l e n t

summary of t h e known s t r a t i g r a p h i c d i s t r i b u t i o n o f B r i t i s h S i l u r i a n c o n o d o n t s h a s b e e n p r e s e n t e d by A l d r i d g e ( 1 9 7 5 ) . T h e i r work c l e a r l y s u g g e s t s t h a t n o t o n l y are c o n o d o n t s v e r y u s e f u l g u i d e fossils i n t h e E u r o p e a n S i l u r i a n , b u t a l s o t h a t t h e p r e s e n t l y u s e d s y s t e m of a b o u t 12 zones c a n b e c o n s i d e r a b l y r e f i n e d after a t h o r o u g h taxonomic r e v i s i o n of t h e f a u n a s .

The commonly u s e d S i l u r i a n c o n o d o n t z o n e s

i n E u r o p e a n d N o r t h America a r e l i s t e d a n d c o r r e l a t e d i n F i g . 5 w h i c h a l s o i l l u s t r a t e s t h e r e l a t i o n s between conodont zones and European s t a n d a r d series.

RELATIONS BETWEEN COUODOST AND GRAPTOLITE ZOSAL UNITS

For a hundred years or more, graptolites have served as the principal guide fossils in regional correlation of Ordovician and Silurian rocks in many parts of the world. Although they are still unsurpassed as biostratigraphic tools in shaly facies, the very scattered occurrence or absence of these fossils in many important carbonate units in America and Eurasia has led to problems in applying the graptolite biostratigraphy to such sequences, especially to those so widely developed on the continental shields. On the

other hand, conodonts are present in a wider r m g e of facies types than are graptolites and they may be used for correlations across facies boundaries. The fact that conodonts are most common, and most easily studied, in shelly rocks makes them particularly useful to compliment graptolites in biostratigraphic work. Considerable efforts have been made in recent years to tie the z o n a l system based on conodonts into that based on graptolites. Much

of this work has been carried out in the Atlantic Borderlands where, at relatively numerous localities, stratigraphically diagnostic conodonts and graptolites have been found together or in such a position that they provide useful information regarding the mutual relations between zonal units based on each of these fossil groups. These relations will be briefly reviewed below.

Cambrian No standard graptolite and conodont zone systems have been established for the Cambrian and the biostratigraphic significance of the dendroid graptolites present in rocks of that system remains unclear.

Ordovician

The striking provincialism exhibited by both conodonts and graptolites in large parts of the Ordovician has greatly complicated the work aimed at establishing as precisely as possible the relations between conodont and graptolite zones. However, as shown by recent summaries (Bergstrsm, 1971b, 1973b), there is now a large number of ties between North Atlantic Province conodont zones and the standard

99 SERIES

NORTH ATLANTIC C O N O D O N T ZCNES

BRITISH GRAPTOLITE

AND SUBZONES ~

ZONES

~~

Dicellogr anceps

ASHGlLLlAN

Amorphognarhus ordovicicus

Dicellogr

complanatus

Pleurogr

linearis

~

Amorohoonathus suDerbus

Dicranoqr clingani

CARADOCIAN

13

L0

3

LLANVIRNIAN

Lower

9

-

ARENlGlAN

?

n z

I

P ygodus ansertnus

LLANDEILIAN

z

I

Eopl reclinatus ~ o p lfoliaceus UNNAMED Eopl suecicus Eoplacognaihus variabilrs Microzarkodine parva Parotstodus originalis Prioniodus navis Prioniodus triangularis Oeoikodus evae Prioniodus elegans , Paroistodus oroteus

Didymogr murchisoni Didymogr Didymogr

1

Didymogr

.

extensus

I

I

(Tetragr approximetus)

4

Anisograptidae

Paltodus deltifer

TREMADOCIAN

btfrdus' hirundo

Clonogr tenellus

Cordylodus angulatus

Dicfyonema flabelliforme

B r i t i s h - B a l t i c g r a p t o l i t e zones. A review of t h e r e l a t i o n s between t h e s e z o n a l s y s t e n s , a s now known,

is given

Irl

i'ig.6.

Some p r o g r e s s

h a s a l s o b e e n made i n e l u c i d a t i n g t h e r e l a t i o n s b e t w e e n N o r t h A t l a n t i c P r o v i n c e conodont zo n es and North Am er i can- P aci f i c

Province

g r a p t o l i t e zon es ( B e r g s t r h , 1971b, 1974, 1976b: Landi ng, 1974a) b u t much more work a l o n g t h o s e l i n e s i s n e e d e d .

This applies a l s o t o

t h e p r o b l e n o f t h e p r e c i s e r e l a t i o n s b e t w e e n Midcontineri-1 P r o v i n c e c o n o d o n t u n i t s a n d g r a p t o l i t e z o n e s , f o r whic!i r e l a t i v e l y l i t t l e d i r e c t e v i d e n c e i s now a v a i l a b l e .

The s c a r c i t y o f z o n a l g r a p t o l i t e s

i n r o c k s w i t h h o r t h American M i d c o n t i n e n t P r o v i n c e conodont f a u n a s w i l l d o u b t l e s s make t h i s work b o t h d i f f i c u l t a n d t i m e - c o n s u m i n g .

Silurian

The many g r a p t o l i t e z o n e s r e c o g n i z e d i n t h i s s y s t e m w i t h i n t h e a r e a d e a l t w i t h h e r e i n a r e , by a n d l a r g e ,

somewhat l e s s s a t i s f a c t o r i -

l y t i e d d i r e c t l y i n t o t h e c o n o d o n t z o n a l s u c c e s s i o n t h a n i s t h e case

100

F i g . 7 . C o r r e l a t i o n between European S i l u r i a n s t a n d a r d s e r i e s , conodont z o n e s , and g r a p t o l i t e zo nes. i n t h e Ordovician.

I n h i s s t a n d a r d work, Walliser ( 1 9 6 4 ) p r e s e n t e d a

p r e l i m i n a r y c o r r e l a t i o n between h i s conodont z o n e s and s t a n d a r d g r a 7 t o l i t e z o n e s t h a t i s s t i l l v a l i d in most r e s p e c t s a l t h o u g h s u b s e q u e n t r e s e a r c h h a s made i t p o s s i b l e t o r e f i n e i t t o a c e r t a i n extent.

However,

t h e r e i s s t i l l some u n c e r t a i n t y r e g a r d i n g t h e

p r e c i s e r e l a t i o n b e t w e e n some c o n o d o n t a n d g r a p t o l i t e z o n e s , e s p e c i a l l y i n t h e L l a n d o v e r i a n , a n d more d e t a i l e d c o n o d o n t work i s c l e a r l y needed i n g r a p t o l i t e - b e a r i n g

s e c t i o n s . Fig.7 is an attempt t o

summarize t h e c u r r e n t l y known r e l a t i o n s b e t w e a

S i l u r i a n conodont

and g r a p t o l i t e zo n es .

In t h e c o m b i n e d g r a p t o l i t e - c o n o d o n t

z o n a l systems w e have a

powerful t o o l t o r e c o g n i z e b i o s t r a t i g r a p h i c u n i t s a c r o s s facies and p r o v i n c i a l b o u n d a r i e s , and t o c o r r e l a t e with unusual precision.

Indeed,

,dinits

3ver l a r g e distaric'-s

t h e r e a r e now i n t e r v a l s w i t h i n w h i c h

t r a n s - A t l a n t i c c o r r e l a t i o n s can be achieved w i t h a s t r a t i g r a p h i c r e s o l u t i o n o f a few f e e t , a n d i t i s t o b e e x p e c t e d t h a t f u r - t h r ? - : r e f i n e m e n t w i l l b e p o s s i b l e i n many i n t e r v a l s when a d d i t i o n a l d a t a

become a v a i l a b l e from c r i t i c a l areas a n d k e y s e c t i o n s . f u t u r e g o a l may b e t o t r y t o e s t a b l i s h

one d e t a i l e d

Obvi ousl y, one

z o n a l framework

b a s e d on a l l s t r a t i g r a p h i c a l l y i m p o r t a n t f o s s i l g r o u p s b u t much remains t o be l e a r n e d about t h e mutual r e l a t i o n s between t h e ranges

of r e p r e s e n t a t i v e s of t h e s e g r o u p s b e f o r e a m e a n i n g f u l a t t e m p t a t s u c h a s y n t h e s i s c a n b e made.

CONOUOKTS AND THE EVOLUTION OF THE PROTO-ATLANTIC

F o s s i l s played a s i g n i f i c a n t r o l e i n t h e e a r l y development of the concept of a Proto-Atlantic

Ocean ( W i l s o n , 1 9 6 6 ) a n d i n d i c a t i o n s

f r o m e s p e c i a l l y b e n t h i c m e g a f o s s i l s s u c h as b r a c h i o p o d s a n d t r i l o b i t e s have a l s o been w i d e l y used i n s u b s e q u e n t d i s c u s s i o n s r e g a r d i n g P a l e o z o i c p l a t e t e c t o n i c s a n d t h e e v o l u t i o n of t h e P r o t o - A t l a n t i c (Williams, 1 9 7 3 ; W h i t t i n g t o n a n d Hughes, 1 9 7 2 , 1 9 7 3 ; B u r r e t t ,

1973).

The d i s t r i b u t i o n o f p r e d o m i n a n t l y p l a n k t i c o r e p i p l a n k t i c o r g a n i s m s s u c h as g r a p t o l i t e s a n d c o n o d o n t s h a s a t t r a c t e d somewhat l e s s i n t e r -

est i n t h e s e d i s c u s s i o n s (Bergstram, 1971a, 1973a, 1976a; Skevington, 1976; B e r g s t r h e t a l . ,

1972, 1 9 7 4 ) . T h i s might b e r e l a t e d t o t h e

f a c t t h a t t h e v e r y w i d e h o r i z o n t a l d i s t r i b u t i o n o f many t a x a o f t h e s e g r o u p s c e r t a i n l y s u g g e s t s t h a t s u c h f o r m s were c a p a b l e o f c r o s s i n g w a t e r b o d i e s t h a t were l a r g e e n o u g h t o s e r v e a s m i g r a t i o n a l b a r r i e r s t o n o s t benthic o r g a n i s m s a n d , a c c o r d i n g l y ,

i t might have been assumed

t h a t t h e s e g r o u p s would b e l e s s l i k e l y t o p r o v i d e u s e f u l d a t a r e g a r ding t h e mutual p o s i t i o n s of t h e c o n t i n e n t a l p l a t e s , T h i s i d e a i s r e e n f o r c e d by t h e f a c t t h a t , a s h a s b e e n n o t e d by Cook a n d T a y l o r ( 1 9 7 5 ) , t h e d e g r e e o f f a u n a l r e s e m b l a n c e b e t w e e n two areas i s n o t n e c e s s a r i l y d i r e c t l y r e l a t e d t o t h e g e o g r a p h i c d i s t a n c e b e t w e e n them, and p r e s u m a b l y ,

t h i s i s l i k e l y t o a p p l y t o planlctic and e p i p l a n k t i c

f o r m s e v e n more t h a n t o b e n a h i c o r g a n i s m s .

However, t h i s s t u d y i s

concerned w i t h a time i n t e r v a l and a g e o g r a p h i c r e g i o n c h a r a c t e r i z e d by v e r y a c t i v e s e a f l o o r s p r e a d i n g and i t i s t h e r e f o r e a p p r o p r i a t e t o c o n s i d e r b r i e f l y t h e r e l a t i o n s between t h e c o n o d o n t f a u n a s i n Europe and N o r t h America and t h e g e n e r a l model o f t h e d e v e l o p m e n t of t h e Prot o-A t l a n t i c

.

Even a c a s u a l l o o k a t t h e t r a n s - A t l a n t i c r e l a t i o n s during Cambro-Silurian

conodont f a u n a l

t i m e shows t h a t t h e r e i s a p p a r e n t l y

no s i m p l e r e l a t i o n b e t w e e n v a r y i n g f a u n a l r e s e m b l a n c e a n d g e o g r a p h i c

proximity of t h e

NQrth-European and North American p l a t e s ,

t h e p e r i o d o f maximum e x p a n s i o n of t h e P r o t o - A t l a n t i c

During

i n t h e Cambrian,

c o n o d o n t f a u n a s show a h i g h d e g r e e o f s i m i l a r i t y r e g i o n a l l y w i t h In Early Ordovician t i m e ,

numerous c o s m o p o l i t a n t a x a .

a striking

p r o v i n c i a l d i f f e r e n t i a t i o n developed, which l a s t e d through v i r t u a l l y the e n t i r e period.

This r e s u l t e d i n t h e establishment of Midcontinent

Province f a u n a s o v e r t h e North American P l a t f o r m a n d t h e s t r i k i n g l y d i f f e r e n t N o r t h A t l a n t i c P r o v i n c e f a u n a s i n n o r t h w e s t e r n Europe a n d , i n t e r e s t i n g l y , i n r e g i o n s a l o n g t h e e a s t e r n and w e s t e r n m a r g i n s o f t h e Iiorth American c r a t o n .

Due t o t h e f a c t t h a t most o f t h e p e r t i n e n t

f a u n a s have n o t y e t been r e v i s e d on m u l t i e l e m e n t b a s i s ,

i t is current-

l y i m p o s s i b l e t o g i v e m e a n i n g f u l n u m e r i c a l v a l u e s of f a u n a l resein-

b l a n c e b e t w e e n t h e two p r o v i n c e s d u r i n g d i f f e r e n t t i m e i n t e r v a l s i n t h e O r d o v i c i a n ; however,

i t a p p e a r s t h a t t h e d i f f e r e n c e s were

e s p e c i a l l y c o n s p i c u o u s d u r i n g Middle O r d o v i c i a n

(Champlainian) t i m e .

T h i s p e r i o d o f maximum c o n o d o n t p r o v i n c i a l i s m i s n o t i n p h a s e w i t h commonly p r o p o s e d m o d e l s f o r t h e e v o l u t i o n o f t h e P r o t o - A t l a n t i c , w h i c h s u g g e s t maximum c o n t i n e n t a l s e p a r a t i o n i n t h e L a t e C a m b r i a n (when c o n o d o n t f a u n a s a r e l a r g e l y c o s m o p o l i t a n ) a n d s u c c e s s i v e c l o s i n g d u r i n g t h e O r d o v i c i a n , t h a t i s , d u r i n g t h e p e r i o d o f most pronounced conodont p r o v i n c i a l i s m .

I t should be n o t e d ,

however,

that

t h e c o s m o p o l i t a n f a u n a s i n t h e S i l u r i a n a r e i n a c c o r d w i t h a model of a t h e n l a r g e l y s u b d u c t e d P r o t o - A t l a n t i c

(Fig.4).

The i m p o r t a n t f a c t t h a t N o r t h A t l a n t i c P r o v i n c e c o n o d o n t f a u n a s a r e p r e s e n t n o t o n l y i n E u r o p e b u t a l s o on t h e A m e r i c a n s i d e o f t h e Proto-Atlantic

i n r e g i o n s c l e a r l y b e l o n g i n g t o t h e N o r t h American

p l a t e ( F i g . 2 ) i n d i c a t e s t h a t t h e Ordovician P r o t o - A t l a n t i c w a s an i n e f f i c i e n t migration b a r r i e r t o t h e s e conodonts. Also, i t is clear t h a t t h e prime f a c t o r s t h a t served t o prevent migration of t h e s e faunas i n t o t h e Midcontinent

P r o v i n c e a r e a f u r t h e r on t o t h e c r a t o n

evidently did not include geographic distance. l y t h a t t h e y were o f e c o l o g i c c h a r a c t e r .

Rather,

c o n t r o l has been d e a l t w i t h r e p e a t e d l y i n r e c e n t y e a r s 1973; Barnes and F s h r a e u s , and Carnes,

i t seems l i k e -

The n a t u r e o f t h i s e c o l o g i c a l

1975; B e r g s t r a m ,

i n p r e s s ; Sweet and BergstrBm,

(Barnes et al.,

1971a, 1973a; Bergstram 1974) and a d i s c u s s i o n of

i t is b e y o n d t h e s c o p e o f t h e p r e s e n t p a p e r .

Y e t i t is o f i n t e r e s t

t o n o t e t h a t t h e s e e c o l o g i c a l f a c t o r s (among w h i c h water t e m p e r a t u r e no d o u b t was i m p o r t a n t ) a p p a r e n t l y a l s o s t r o n g l y i n f l u e n c e d t h e d i s t r i b u t i o n a l patterns of several megafossil groups, including

103 g r a p t o l i t e s and brachiopods. I n v i e w o f t h e a p p a r e n t l y i n s i g n i f i c a n t r o l e p l a y e d by g e o g r a p h ic distance alone vis-a-vis

e c o l o g i c a l f a c t o r s f o r t h e changing

c o n o d o n t d i s t r i b u t i o n a l p a t t e r n s p a r t i c u l a r l y i n t h e Cambro-Ordovici a n , a l o n g w i t h t h e f a c t t h a t v e r y s i m i l a r c o n o d o n t f a u n a s were p r e s e n t on b o t h s i d e s o f t h e P r o t o - A t l a n t i c ,

i t a p p e a r s t h a t cono-

donts are n o t l i k e l y t o p r o v i d e c r i t i c a l d a t a toward a n i n t e r p r e t a t i o n of t h e r e l a t i v e w i d t h o f t h e P r o t o - A t l a n t i c d u r i n g d i f f e r e n t time i n t e r v a l s .

A c c o r d i n g l y , one h as t o b e c o n t e n t w i t h t h e f a c t

t h a t although conodonts are s u p e r i o r t o o l s f o r t r a n s - A t l a n t i c correlations, a t least at the present t i m e they give l i t t l e evidence r e g a r d i n g tk s i z e a n d d e v e l o p m e n t o f t h e P r o t o - A t l a n t i c Ocean.

ACKNOWLEDGEMENTS

I a m indebted t o Dr.

Walter C.

Sweet f o r r e a d i n g t h e m a n u s c r i p t

and o f f e r i n g v a l u a b l e comments a n d t o Mrs. H e l e n J o n e s a n d Mrs. K a r e n Tayler f o r t e c h n i c a l a s s i s t a n c e .

REF EKENCES

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A . t h e s i s , U n i v . o f M i s s o u r i , C o l u m b i a , 110 p p . B u l n a n , O.M.B., 1970. G r a p t o l i t h i n a w i t h s e c t i o n s on E n t e r e p n e u s t a and P t e r o b r a n c h i a . & T e i c h e r t , C. ( E d . ) , T r e a t i s e o n I n v e r t e b r a t e P a l e o n t o l o g y , V ( 2 n d e d . ) , 1 6 3 pp. B u r r e t t , C . , 1 9 7 3 . O r d o v i c i a n b i o g e o g r a p h y and c o n t i n e n t a l d r i f t : P a l a e o g e o g r . , P a l a e o c l i m . , P a l a e o e c o l . , 13, 1 6 1 - 2 0 1 . Cook, H.E., a n d T a y l o r , M.E., 1 9 7 5 . E a r l y P a l e o z o i c c o n t i n e n t a l margin s e d i m e n t a t i o n , t r i l o b i t e b i o f a c i e s , and t h e t h e r m o c l i n e , w e s t e r n U n i t e d S t a t e s : G e o l o g y , 3:10, 5 5 9 - 5 6 2 . Cooper, B.J., 1975. 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,

,

,

,

,

105 E t h i n q t o n , R . L . , a n d F u r n i s h , li., 1 9 6 2 . S i l u r i a n a n d D e v o n i a n c o n o d o n t s from S p a n i s h S a h a r a : J o u r . P a l e o n t . , 36, 1253-1290. Fzhraeus, L. E . , 1 9 7 0 . C o n o d o n t - b a s e d c o r r e l a t i o n s o f Lower a n d M i d d l e O r d o v i c i a n s t r a t a i n w e s t e r n N e w f o u n d l a n d : G e o l . S O C . America Bdll., 8 1 , 2 0 6 1 - 2 0 7 6 . F z h r n e u s , L.E., 1973. D e p o s i t i o n a l e n v i r o n n e n t s and c o n o d o n t - b a s e d c o r r e l a t i o n s o f t h e Long P o i n t F o r m a t i o n ( M i d d l e O r d o v i c i a n ) w e s t e r n S e w f o u n d l a n d : Can. J o u r . E a r t h S c i . , 10, 1822-18.33. 1 9 7 4 . Zur S i l u r / D e v o n - G r e n z r i n F e i s t , R . , and S c h i j n l a u b , H . - P . , 8 s t l i c h e n Montagne K o i r e S G d - F r a n k r e i c h s : Neues J a h r b . G e o l . P a l a o n t . Monatsh., J a h r g . 1 9 7 4 , 4 , 200-219. F u g a n t i , A., a n d S e r p a g l i , E . , 1 9 6 8 . G e o l o g i c a l r e m a r k s on U r b a n a L i m e s t o n e a n d e v i d e n c e for i t s Upper O r d o v i c i a n a g e b y means o f c o n o d o n t s - e a s t e r n S i e r r a Elorena, S o u t h S p a i n : G e o l . S O C , I t a l . B o l l . , 8 7 , 511-521. H a m a r , G . , 1 9 6 4 . The b l i d d l e O r d o v i c i a n o f t h e Oslo R e g i o n , Norway. 17. Conodonts from t h e lower Middle O r d o v i c i a n o f R i n g e r i k e : Korsk G e o l . T i d s s k r . , 44, 243-292. Ha.nar, G . , 1 9 6 6 . The M i d d l e O r d o v i c i a n o f t h e Oslo R e g i o n , Norway, 22. P r e l i m i n a r y r e p o r t on co n o d o n t s from t h e Oslo-Asker and R i n g e r i k e d i s t r i c t s : Norslc G e o l . T i d s s k r . , 4 6 , 2 7 - 8 3 . S e l f r i c h , C . T . , 1 9 7 5 . S i l u r i a n c o n o d o n t s f r o m \Gills M o u n t a i n a n t i c l i n e , V i r g i n i a , West V i r g i n i a , a n d M a r y l a n d : G e o l . S O C . A m e r . S p e c . P a p e r 1 6 1 , 8 2 pp.+ a p p e n d i x . J e p p s s o n , L . , 1 9 7 5 . A s p e c t s of S i l u r i a n c o n o d o n t s : F o s s i l s and S t r a t a 6 , 54 pp. KnGpfer, J., 1 9 6 7 . Z u r Fauna und B i o s t r a t i g r a p h i e d e s O r d o v i c i u m s ( G r s f e n t h a l e r S c h i c h t e n ) i n ThGringen: F r e i b e r g e r ForschungsH e f t e , C220, 119 p p . K o c k e l , F . , 1 9 5 8 . C o n o d o n t e n a u s dern P a l a o z o i k u m von M a l a g a (SiidS p a n i e n ) : Seues J a h r b . Geol. P a l s o n t . Monatsh., Jahrg.,225-263. K o h u t , J. J . , 1 9 7 2 . Conodont b i o s t r a t i g r a p h y o f t h e Lower O r d o v i c i a n O r t h o c e r a s a n d S t e i n L i m e s t o n e s ( 3 c ) , Norway: N o r s k G e o l . T i d s s k r . , 5 2 , 427-445. Lamont, A . , a n d L i n d s t r B n , b l . , 1 9 5 7 . A r e n i g i a n and L l a n d e i l i a n c h e r t s i d e n t i f i e d i n t h e S o u t h e r n U p l a n d s o f S c o t l a n d b y means o f c o n o d o n t s , e t c . : E d i n b u r g h G e o l . S O C , T r a n s , , 17:1, 6 0 - 7 0 . L a n d i n g , E., 1 9 7 4 a . Lower O r d o v i c i a n c o n o d o n t a n d g r a p t o l i t e b i o s t r a t i g r a p h y o f t h e T a c o n i c P r o v i n c e , e a s t e r n N e w York: Geol. S O C . America, A b s t r . w i t h P r o g r . , 6 : 6 , 5 2 5 - 5 2 6 . L a n d i n g , E . , 1 9 7 4 b . E a r l y a n d M i d d l e C a m b r i a n c o n o d o r i t s from t h e T a c o n i c A l l o c h t h o n , e a s t e r n Sew York : J o u r . P a l e o n t . , 48 12411248. L a n d i n g , E . , 1 9 7 6 . L a t e C a m b r i a n P r o o n e o t o d u s t e n u i s (Miiller ) a p p a r a t u s e s and a s s o c i a t e d conodonts from t h e Taconic Allochthon, e a s t e r n N e w York: G e o l . S O C . A m e r i c a , A b s t r . w i t h P r o g r . , 8 : 4 , 487-488. 1970. Conodonten a u s d e r Choson-Gruppe ( U n t e r e s O r d o v i z Lee, H . - Y . , i u m ) von K o r e a : Neues J a h r b . G e o l . P a l z o n t . A b h . , 1 3 6 : 3 , 303344. L e e , H.-Y., 1 9 7 5 . C o n o d o n t e n aus dem u n t e r e n und n i t t l e r e n O r d o v i z ium von N o r d k o r e a : P a l a e o n t o g r a p h i c a , A b t . A , 1 5 0 , 1 6 1 - 1 8 6 . 1968. Conodonts and f i s h r e m a i n s from t h e S t o n e h o u s e L e g a u l t , J.A., F o r m a t i o n , A r i s a i g , Nova S c o t i a : C a n a d a G e o l . S u r v . B u l l . 1 6 5 , 3 0 ??. L i n d s t r a m , M., 1955. Conodonts from t h e lowermost O r d o v i c i a n s t r a t a o f s o u t h - c e n t r a l Sweden: Geol. F a r e n . S t o c k h o l n F 6 r h a n d l . , 7 6 , 517-614.

,

106 L i n d s t r b n , >I., 1959. Conodonts f r o m t h e Crdg L i m e s t o n e ( O r d o v i c i a n , Wales) : M i c r o p a l e o n t o l o g y , 5 , 4 2 7 - 4 5 2 . L i n d s t r i j n , bl., 1960. A Lower-Middle O r d o v i c i a n s u c c e s s i o n o f c o n o d o n t f a u n a s : I n t e r n a t . Geol. Congr., XXI S e s s . , Repts., 7 , 88-96. L i n d s t r B n , b l . , 1 9 7 1 . Lower O r d o v i c i a n c o n o d o n t s o f E u r o p e : G e o l . S O C . A m e r i c a M e m . 1 2 7 , 21-61. L i n d s t r B m , M., R a c h e b o e f , P. R . , a n d H e n r y , J . - L . , 1 9 7 4 . O r d o v i c i a n conodonts from t h e P o s t o l o n n e c Formation (Crozon P e n i n s u l a , Massif A r m o r i c a i n ) a n d t h e i r s t r a t i g r a p h i c s i g n i f i c a n c e : G e o l . e t P a l a e o n t . , 8 , 15-28. 1975. S m a l l s h e l l y f o s s i l s ?.!atthews, S . C . , a n d M i s s a r z h e v s k y , V . V . , o f l a t e P r e c a m S r i a n and e a r l y Cambrian a g e : a r e v i e w o f r e c e n t work: G e o l . S O C . Londsn J o u r . , 131, 2 8 9 - 3 0 4 . a n d Opdyke, K . D . , 1973. R e m a g n e t i z a t i o n h y p o t h e s i s blcElhinny, M.W., d i s c o u i t e d : a pxleomagnetic s t u d y of t h e Trenton Limestone, N e w York S t a t e : G e o l . S O C . America B u l l . , 8 4 , 3 6 9 7 - 3 7 0 8 . b l i l l e r , J . F . , 1 9 6 9 . Conodont f a u n a of t h e Notch Peak L i m e s t o n e ( C a m b r o - O r d o v i c i a n ) , House R a n g e , U t a h : J o u r . P a l e o n t . , 4 3 , 413-4.39. Miller, J . F . , 1975. Conodont f a u n a s from t h e Cambrian a n d l o w e s t O r d o v i c i a n o f w e s t e r n N o r t h America: G e o l , S O C . America, A b s t r . w i t h P r o g r . , 7 : 7 , 1200-1201. Miller, J.F., a n d R u s h t o n , A . k ' . A . , 1973. 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Bull., 405, 105 pp. S e r g e e v a , S . P . , 1964. On t h e s i g n i f i c a n c e of t h e Lower O r d o v i c i a n c o n o d o n t s i n t h e L e n i n g r a d r e g i o n : L e n i n g r a d Univ. V e s t n i k , S e r . G e o l o g i y a i G e o g r a f i i , 12:2, 56-60. ( i n R u s s i a n ) . S e r p a g l i , E . , 1967. I c o n o d o n t i d e l l ' O r d o v i c i a n o S u p e r i o r e ( A s h g i l l i a n o ) d e l l e A l p i C a r n i c h e : S O C , P a l e o n t . I t a l . Bo11.,6, 30-111. S e r p a g l i , E . , 1974, L o w e r O r d o v i c i a n c o n o d o n t s f r o m P r e c o r d i l l e r a n > A r g e n t i n a ( P r o v i n c e of S a n J u a n ) : S O C . P a l e o n t . I t a l . Boll., 13, 17-98. S k e v i n g t o n , D . , 1976. P r o t o c h o r d a t e s , p a l a e o l a t i t u d e s a n d t h e P r o t o A t l a n t i c O c e a n : G e o l . S O C . America, A b s t r . w i t h P r o g r . , 8 : 2 ,

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108 a n d c o n o d o n t f a u n a s f r o m t h e S i l u r i a n a n d Lower D e v o n i a n of Bohemia: G e o l . e t P a l e o n t . , 8 , 39-47. v a n liamel, W.A., 1974. Conodont b i o s t r a t i g r a p h y of,.the Upper Camb r i a n a n d Lower O r d o v i c i a n of n o r t h - w e s t e r n O l a n d , s o u t h e a s t e r n Sweden: U t r e c h t M i c r o p a l e o n t . B u l l . 10, 126 p p . W e b e r s , G.F., 1 9 6 6 . The M i d d l e a n d Upper O r d o v i c i a n c o n o d o n t f a u n a s of Minnesota: Minnesota Geol. S u r v. Spec. Publ . SP-4, 123 pp. W h i t t i n g t o n , H . B . , a n d Hughes, C.P., 1 9 7 2 . O r d o v i c i a n g e o g r a p h y a n d f a u n a l p r o v i n c e s deduced from t r i l o b i t e d i s t r i b u t i o n : Royal S O C . London P h i l . T r a n s . , B263, 235-278. W h i t t i n g t o n , H . B . , a n d Hughes, C . P . , 1 9 7 3 . O r d o v i c i a n t r i l o b i t e d i s t r i b u t i o n and g eo g rap h y : P a l a e o n t o l . Assoc. Spec. Pap., 12, 2 35- 2 40. W i l l i a m s , A . , 1973. D i s t r i b u t i o n o f b r a c h i o p o d a s s e m b l a g e s i n r e l a t i o n t o Ordovician palaeogeography: P a l a e o n t . Assoc. Spec. P a p . , 1 2 , 241-269. Wilson, J . T . , 1 9 6 6 . Did t h e A t l a n t i c c l o s e a n d t h e n r e - o p e n ? N a t u r e , London, 2 1 1 , 6 7 6 - 6 8 1 .

Dr.

I. G.

Sohn:

Discussion Do you c o n s i d e r t h e d i v e r s i t y of c o n o d o n t s t o

be g r e a t e r i n d e e p t h a n i n s h a l l o w w a t e r ? S . M. Bergstrzm: I t i s d i f f i c u l t t o g i v e a d e f i n i t e answer

Dr.

t o t h i s q u e s t i o n b u t a s a r u l e , f a u n a s were more d i v e r s i f i e d i n somewhat d e e p e r t h a n i n v e r y s h a l l o w w a t e r .

In, for in-

s t a n c e , t h e North American Middle O r d o v i c i a n , t h e d i v e r s i t y i n conodont f a u n a s i n c r e a s e s c o n s i d e r a b l y from t h e c e n t r a l p a r t of t h e c o n t i n e n t t o t h e A p p a l a c h i a n s .

It is especially

s t r i k i n g t h a t O r d o v i c i a n p l a t f o r m c o n o d o n t s were much more a b u n d a n t and v a r i e d i n t h e presumably somewhat d e e p e r w a t e r along t h e c p n t i n e n t a l margins t h a n i n t h e s h a l l o w e p i c o n t i n e n t a l s e a s on t h e p l a t f o r m i t s e l f . Dr.

B.

K.

Holdsworth:

1.

What e v i d e n c e i s t h e r e f o r c o n s i d e r -

i n g t h e D a l r a d i a n p a r t of t h e American p l a t e i n Cambrian t i m e , a s t h e o n l y known t r i l o b i t e s d o n o t n e c e s s a r i l y seem t o b e of t h e American p r o v i n c e ? What e v i d e n c e e x i s t s f o r an O r d o v i c i a n ocean e x t e n d i n g n o r t h w a r d s i n t o S.W. E n g l a n d , a l l F r a n c e and w e l l i n t o cen2.

t r a l Europe? Bergstrgm:

A s f a r a s t h e f i r s t q u e s t i o n i s c o n c e r n e d , I am

aware of t h e weaknesses of some of t h e d a t a b e h i n d t h e Cambrian reconstruction.

A s you p c i n t o u t , f a u n a l and g e o l o g i c

e v i d e n c e f o r p l a c i n g p a r t s of t h e B r i t i s h I s l e s , e t c . on one or t h e other s i d e of the Proto-Atlantic i s not very strong and a t t h e p r e s e n t t i m e , i t i s c e r t a i n l y n o t s u f f i c i e n t f o r

109

making any f i r m judgements a s t o t h e f o r m e r g e o g r a p h i c p o s i t i o n s of t h e s e a r e a s .

The p o s i t i o n of t h e B a l t i c S h i e l d i n

my map i s b a s e d on p a l e o m a g n e t i c measurements on M i d d l e Camb r i a n r o c k s t h a t w e have c a r r i e d o u t r e c e n t l y , and I have a d o p t e d t h e c o n v e n t i o n a l view and k e p t p a r t o f t h e B r i t i s h I s l e s -- The E n g l i s h M i d l a n d s , e t c . -- i n a b o u t t h e same geographic p o s i t i o n t o t h e B a l t i c Shield as today.

But I h a v e

no s t r o n g f e e l i n g s r e g a r d i n g where S c o t l a n d i s l i k e l y t o h a v e I b e l i e v e , however, t h a t t h e m a r i n e been i n Cambrian t i m e . Lower P a l e o z o i c s e d i m e n t s o n t h e H e b r i d e a n P l a t f o r m i n n o r t h -

w e s t e r n m o s t S c o t l a n d , f o r i n s t a n c e , t h e Durness L i m e s t o n e , show so c l o s e a f f i n i t i e s w i t h e q u i v a l e n t s e d i m e n t s i n e a s t e r n most N o r t h America, G r e e n l a n d , S p i t s b e r g e n , e t c . t h a t i t i s r e a s o n a b l e t o s u g g e s t t h a t t h e y a l l b e l o n g t o t h e same g e n e r a l province. A s f a r a s t h e s e c o n d q u e s t i o n i s c o n c e r n e d , I have p r e f e r r e d , i n t h e model of t h e E a r l y O r d o v i c i a n P r o t o - A t l a n t i c , t o l e a v e o u t from t h e map C o r n w a l l and t h e o t h e r H e r c y n i a n a r e a s i n t h e S W p a r t of t h e B r i t i s h I s l e s .

I personally believe

t h a t t h e r e w a s a mid-European sea e x t e n d i n g i n t o t h a t area a s s u g g e s t e d by o t h e r a u t h o r s , b u t I do n o t know i f C o r n w a l l

w a s a p a r t of Great B r i t a i n o r n o t d u r i n g E a r l y O r d o v i c i a n

time. Dr.

J. W.

Neale:

I f I c a n f o l l o w up w h a t D r .

Holdsworth s a i d ,

I w a s r a t h e r w o r r i e d a b o u t some of y o u r p l a t e t e c t o n i c r e c o n -

structions.

I n terms of t h e c o n o d o n t s , I n o t i c e d t h i s p a r -

t i c u l a r l y i n y o u r L l a n d e i l i a n r e c o n s t r u c t i o n where you had your American and N o r t h A t l a n t i c f a u n a s s h a r p l y s e p a r a t e d somewhere i n t h e r e g i o n of t h e A p p a l a c h i a n s .

A t t h e same

t i m e , t h e p r o t o - A t l a n t i c Ocean a p p a r e n t l y had no e f f e c t on t h e e a s e o f d i s s e m i n a t i o n of c o n o d o n t s from t h e European a r e a s t o t h e e a s t American a r e a . I n t h i s i n s t a n c e i f y o u r p r o t o - o c e a n i s no b a r r i e r t o y o u r N o r t h A t l a n t i c f a u n a , what c o n t r o l s t h e s h a r p d i v i s i o n between y o u r N o r t h A t l a n t i c f a u n a and y o u r American f a u n a i n t h e A p p a l a c h i a n a r e a ?

In

o t h e r w o r d s , would i t n o t b e b e t t e r t o a t t a c h t h e e a s t Americ a n p a r t of your p l a t e t o t h e European a r e a a t t h a t t i m e ? Bergstram: T h i s i s a v e r y i n t e r e s t i n g q u e s t i o n and a problem on w h i c h , a s you know, I have b e e n working f o r s e v e r a l y e a r s . I t i s

110

s t r i k i n g how s i m i l a r t h e Lower-Middle O r d o v i c i a n c o n o d o n t faunas i n t h e e a s t e r n p a r t of t h e Appalachians are t o t h o s e i n Europe. by s p e c i e s .

I n many cases o n e c a n s i m p l y m a t c h f a u n a s s p e c i e s On t h e o t h e r h a n d , i f o n e g o e s t o t h e w e s t e r n

Appalachians t w e n t y - t h i r t y miles t o t h e w e s t , one encounters M i d c o n t i n e n t - t y p e c o n o d o n t f a u n a s w h i c h a r e v i r t u a l l y completely different.

F o r a w h i l e , I was i n c l i n e d t o b e l i e v e

t h a t maybe, t h e r e w a s a p l a t e b o u n d a r y b e t w e e n t h e s e two conodont f a u n a l provinces.

However, i f o n e s t u d i e s t h e l o c a l

Ordovician geology i n Tennessee, V i r g i n i a , e t c . , one f i n d s

-

t h a t e v e n i f t h e s e r o c k s h a v e b e e n t h r u s t e d some d i s t a n c e

probably a r a t h e r s h o r t d i s t a n c e - t o t h e northwest, one can t r a c e many f o r m a t i o n s from t h e w e s t e r n A p p a l a c h i a n s i n t o a t l e a s t t h e c e n t r a l p a r t of t h e A p p a l a c h i a n V a l l e y ; a c c o r d i n g l y , t h e r e a p p e a r s t o b e no r e a s o n t o r e g a r d t h e c o n o d o n t f a u n a l p r o v i n c i a l boundary as c o i n c i d i n g w i t h a p l a t e boundary.

Ac-

t u a l l y , t h e r e i s a zone o f t r a n s i t i o n t h a t may b e o n e o r t w o t h r u s t b e l t s w i d e i n w h i c h some N o r t h A t l a n t i c p r o v i n c e e l e m e n t s a r e mixed w i t h r e p r e s e n t a t i v e s of t h e M i d c o n t i n e n t p r o v i n c e , and t h i s r a t h e r n a r r o w b e l t h a s b e e n n o t e d l o c a l l y from Alabama a l l t h e way u p t o Maryland i n t h e c e n t r a l p a r t of t h e A p p a l a c h i a n V a l l e y . I t h i n k t h i s f a u n a l d i f f e r e n t i a t i o n i n t h e Appalachian Val-

l e y i s l i k e l y t o h a v e b e e n c a u s e d by e c o l o g i c a l c o n t r o l , n o t by g e o g r a p h i c s e p a r a t i o n .

I believe t h a t basic controlling

f a c t o r s were w a t e r t e m p e r a t u r e and w a t e r d e p t h .

According t o

r e c e n t l y p u b l i s h e d r e c o n s t r u c t i o n s by Walker and o t h e r s of s e d i m e n t a r y e n v i r o n m e n t s i n t h e M i d d l e O r d o v i c i a n of e a s t e r n T e n n e s s e e , t h e c r i t i c a l a r e a was n o t o n t h e c o n t i n e n t a l s l o p e b u t on t h e o u t e r p a r t o f t h e p l a t f o r m .

The N o r t h A t l a n t i c

c o n o d o n t s p r e f e r r e d t h e somewhat d e e p e r w a t e r a l o n g t h e cont i n e n t a l m a r g i n , and w i t h few e x c e p t i o n s , t h e y d i d n o t i n h a b i t t h e s h a l l o w e r water f a r t h e r o n t o t h e p l a t f o r m .

Although

now p a r t l y o b s c u r e d by t h r u s t f a u l t s , t h e t r a n s i t i o n z o n e may h a v e b e e n f i v e m i l e s o r so w i d e w h e r e o n e c a n g o from o n e t y p e of fauna i n t o a n o t h e r .

So I d o n o t t h i n k t h a t t h e p r e -

s e n t p r o v i n c i a l d i f f e r e n t i a t i o n of conodonts i n t h a t a r e a can s e r v e f o r i d e n t i f i c a t i o n of p l a t f o r m b o u n d a r i e s .

111 LATE P A L E O Z O I C AND T R I A S S I C CONODONT BIOSTRATIGRAPHY: CORRELATIONS AROUND THE E X P A N D I N G ATLANTIC OCEAN

David L . C l a r k D e p a r t m e n t o f Geology a n d G e o p h y s i c s U n i v e r s i t y o f W i s c o n s i n , Madison ABSTRACT The b e s t L a t e Devonian c o n f i g u r a t i o n f o r t h e p r e s e n t A t l a n t i c b o r d e r l a n d a r e a i n c l u d e s N o r t h America and n o r t h e r n Europe i n c o n t a c t o r c l o s e p r o x i m i t y and a " p r o t o - A t l a n t i c Ocean" s e p a r a t i n g t h e s e c o n t i n e n t s f r o m A f r i c a and S o u t h America.

D u r i n g t h e C a r b o n i f e r o u s , t h e A f r i c a - S o u t h America b l o c k

approached t h e North America-northern Europe b l o c k , d e s t r o y i n g t h e " p r o t o - A t l a n t i c " and d u r i n g t h e P e r m o - T r i a s s i c , t h e r e w a s no m a j o r s e p a r a t i o n o f a t e n u o u s l y f u s e d S o u t h A m e r i c a , A f r i c a , N o r t h America, E u r o p e c o n t i n e n t .

By L a t e T r i a s s i c , t h e p r e s e n t

N o r t h A t l a n t i c b e g a n foYming a s t h e E u r o p e a n a n d A f r i c a n c o n t i nents began t h e s h i f t t o t h e i r p r e s e n t p o s i t i o n s . The r e l a t i o n s h i p o f t h i s c o n t i n e n t a l movement t o c o n o d o n t b i o s t r a t i g r a p h y on e i t h e r s i d e of t h e p r e s e n t A t l a n t i c Basin c a n b e compared u s i n g t h e s i m i l a r i t y i n d e x , 2w/ a conodont f o r m - s p e c i e s .

+

b, for

Conodont s i m i l a r i t y b e t w e e n E u r o p e and

N o r t h America was g r e a t e s t d u r i n g t h e L a t e D e v o n i a n and P e r mian, w i t h a g r a d u a l decrease i n t h e T r i a s s i c t h a t m i g h t b e r e l a t e d t o formation of t h e p r e s e n t A t l a n t i c Basin. i n d i c e s among o t h e r A t l a n t i c b o r d e r l a n d

Similarity

c o n t i n e n t s a r e some-

what ambiguous, a s f a r a s d o c u m e n t i n g c o n t i n e n t a l p r o x i m i t y . T h i s i s b e c a u s e of l i m i t e d t a x o n o m i c d a t a ,

Also, such t h i n g s

a s low C a r b o n i f e r o u s A t l a n t i c b o r d e r l a n d c o n o d o n t s i m i l a r i t y may b e e x p l a i n e d by o t h e r f a c t o r s s u c h a s t h e e c o l o g i c i d i o s y n c r a s i e s of t h e a n c i e n t P a c i f i c and T e t h y a n w a t e r masses, or different continental elevations during t h e t i m e interval.

Re-

g a r d l e s s , some 100 c o n o d o n t z o n e s ( 4 3 D e v o n i a n , 23 C a r b o n i f e r ous, 1 2 Permian, 22 Triassic) p r o v i d e an important b i o s t r a t i g r a p h i c framework f o r t h e A t l a n t i c b o r d e r l a n d s . A c a l c u l a t e d z o n a l s i m i l a r i t y i n d e x m i m i c s t h a t of

form-species index.

the

The g r e a t e s t z o n a l s i m i l a r i t y i s d u r i n g

t h e L a t e D e v o n i a n , much l e s s d u r i n g t h e C a r b o n i f e r o u s , b u t h i g h again i n t h e Triassic b e f o r e dropping i n t h e L a t e Triassic, perhaps, i n p a r t , r e f l e c t i n g L a t e T r i a s s i c s e p a r a t i o n of North America and E u r o p e .

112

R~SUM~ La meillure configuration du d6vonien rkcent pour la r6giI on de bord actuelle de 1'Atlantique comprend l'Amerique du Nord et 1'Europe du nord, soit en contacte l'un avec l'autre soit en proche proximitk , et une "Oc6an proto-Atlantique" qui skpare ces continents de 1'Afrique et 1'Amkrique du Sud. Pendant le

carbonif&re, le bloc comprenant 1'Am;rique du Sud et 1'Afrique se rapprochait du bloc comprenant l'Am&ique du Nord et 1'Europe du nord. La "proto-Atlantique" ktait dktruite et pendant le permo-trias, il n'y avait aucune division dans le continent tentativement li6 de 1 'Amkrique du Sud , 1 'Afrique, 1 'Amhrique du Nord et 1'Europe. Par le trias rkcent, 1'Atlantique du Nord actuelle avait commenc; h prendre forme pendant que les continents europken et africain prenaient leurs positions actuelles. Le rapport de ce mouvement continental 'a la biostratigraphie conodonte des deux cotes du Bassin Atlantique actuel peut 2tre compar;! en utilisant l'indice de similitude, 2w/a+b , pour le genre-forme conodont. La similitude conodonte entre 1'Europe et 1'Amkrique du Nord ktait la plus grande pendant le dkvonien rkcent et le permien, avec une iente r6duction pendant le trias qui pourrait se rapporter la formation du Bassin AtI lantique actuel. Les indices de similitude parmi d'autres regions de bord de 1'Atlantique sont assez ambiguzs, quant 'a la documentation de la proximit; continentale. Ceci est dii aux I donnees taxonomiques limitkes. A U S S ~ ,des choses c o m e une basse similitude conodonte de la r.&gion de bord de 1'Atlantique carbonifLre peuvent hetre expliqu.&es par d'autres facteurs comme les idiosyncrasies des anciennes masses d'eaux de la Pacifique et Tethyan ou des differentes kl6vations continentales pendant ces p&iodes de temps. NQanmoins, il y a une centaine de zones conodontes (43 devoniennes, 23 carbonifbres, 12 permiennes, 22 trias) qui comprennent un cadre biostratigraphique important pour les r6gions de bord de 1'Atlantique. Une indice de similitude zonale calcul&e copie celle du genre-forme. La plus grande similitude zonale arrive pendant le dkvonien rkcent, encore moins pendant le carbonifkre, mais beaucoup plus encore pendant le trias avant de se rabaisser pendant le trias rAcent, peut-Gtre ainsi r&flLchissant en partie la s;!paration de l'Am&ique du Nord de 1'Europe pendant le trias rkcent.

113

INTRODUCTION

Worldwide c o n o d o n t b i o s t r a t i g r a p h y was summarized i n 1 9 7 1 (Sweet and B e r g s t r o m , 1 9 7 1 ) .

Since t h e n advances i n conodont

r e s e a r c h p r i m a r i l y have been i n a r e a s of b i o l o g y , paleoecology and p a l e o g e o g r a p h y .

Because s i g n i f i c a n t new i d e a s h a v e d e v e l -

oped c o n c e r n i n g c o n t i n e n t a l p l a c e m e n t d u r i n g t h e g e o l o g i c p a s t , i t i s now p o s s i b l e t o r e l a t e c o n o d o n t b i o s t r a t i g r a p h y more

c l o s e l y t o paleogeography.

N e w P h a n e r o z o i c w o r l d maps h a v e

provided a base f o r A t l a n t i c borderland b i o s t r a t i g r a p h y , i n particular

(Smith and o t h e r s , 1 9 7 3 ) .

T h i s p a p e r , w h i l e r e v i e w i n g and i n some i n s t a n c e s u p d a t i n g L a t e P a l e o z o i c and T r i a s s i c c o n o d o n t b i o s t r a t i g r a p h y ,

in-

cludes an a t t e m p t a t r e l a t i n g t h e A t l a n t i c Basin development of t h e t i m e t o c o n o d o n t s i m i l a r i t i e s i n t h e b o r d e r l a n d s . A t l a n t i c borderlands geology i n c l u d e s l i t t l e marine Pennsylvani a n , Permian o r T r i a s s i c .

The p o r t i o n o f t h i s r e v i e w r e l a t e d

t o c o n o d o n t s of t h e s e s y s t e m s i s b a s e d on w e s t e r n N o r t h A m e r i c a n and E u r o p e a n o c c u r r e n c e s t h a C , i n t h e s t r i c t e s t s e n s e , a r e not Atlantic borderlands.

The s i m i l a r i t i e s and d i f f e r e n c e s

among t h e s e c o n o d o n t f a u n a s a r e r e l a t e d d i r e c t l y t o t h e A t l a n t i c B a s i n d e v e l o p m e n t , however, and have a l e g i t i m a t e p l a c e i n any d i s c u s s i o n of A t l a n t i c B a s i n b o r d e r l a n d b i o s t r a t i g r a p h y . DEVONIAN

Introduction Devonian c o n o d o n t s a r e w e l l known i n t h e B r i t i s h I s l e s , Belgium, Germany, F r a n c e , S p a i n , P o r t u g a l and w e s t e r n N o r t h A f r i c a (Morocco and S p a n i s h S a h a r a ) f o r t h e e a s t e r n A t l a n t i c b o r d e r l a n d s , b u t l e s s w e l l known a l o n g t h e A t l a n t i c s e a b o a r d o f N o r t h America a n d r e l a t i v e l y unknown i n S o u t h America.

The

most c o m p r e h e n s i v e b i o s t r a t i g r a p h y i s b a s e d on work i n c e n t r a l Flirope (Germany, A u s t r i a , P o l a n d , B u l q a r i a , and I t a l y ) and w e y t e r n and c e n t r a l N o r t h America ( I o w a , I l l i n o i s , Nevada, Utah, O n t a r i o , A l b e r t a , and t h e A r c t i c I s l a n d s ) ,

The p r e c i s i o n

of Upper Devonian c o r r e l a t i o n a c r o s s t h e p r e s e n t A t l a n t i c B a s i n i s u n e x c e l l e d i n any o t h e r s y s t e m .

D e t a i l s o f L o w e r and M i d d l e

Devonian f a u n a s a r e n o t a s c o m p r e h e n s i v e .

114

Fig. 1. Devonian to Triassic "index" species. A l l figures except 14, adapted from Lindstrom, 1964. Figures, X28, except as indicated. 1

-

2

3

4 - 6

Epigondolella mungoensis (Diebel): 1, lateral: 2 , upper view; Upper Middle Triassic species; genus important in Upper Triassic, as well. Neospathodus cristagalli (Huckriede); Lower Triassic species: genus important in Upper Permian and throughout Triassic. Ellisonia sp.; multielement species important in Upper Permian and Triassic: 4, LC-element; 5, ozarkodinid element; 6 , U-element. (continued on next page)

115

Lower Devonian Gedinnian The m o s t i m p o r t a n t G e d i n n i a n c o n o d o n t i s I c r i o d u s w o s c h m i d t i ( F i g . 1 ) . I t marks t h e b a s e o f t h e Devonian o n b o t h s i d e s of t h e A t l a n t i c and r a n g e s t h r o u g h much o f t h e G e d i n n i a n ,

a t l e a s t a s r e c o g n i z e d i n N e w York Other s p e c i e s of I c r i o d u s

288).

-

v i s i n E u r o p e and

(2

I. latericrescens

Klapper

g . , 1971,

e-woschmidti,

p.

I.pesa-

i n North A m e r i c a ) p l u s

s p e c i e s of S p a t h o g n a t h o d u s c o m p r i s e t h e i m p o r t a n t Upper G e d i n n i a n c o n o d o n t s ( F i g . 2). F i g u r e 1 ic oi:ti nueri) 7 - 8 9 - 10

11 12

-

13

14

Giadiogondolella tethydis (Huckriede); 7 , upper; 8 , lower view; Middle T r i a s s i c s p e c i e s . F u r n i s h i u s t r i s e r r a t u s C l a r k ; 9 , l a t e r a l . ; 10, u p p e r view; Lower Triassic s p e c i e s . N e o g o n d o l e l l a s e r r a t a ( C l a r k and E t h i n g t o n ) ; Upper Permian s p e c i e s ; genus i m p o r t a n t t h r o u g h o u t Permian and Lower a n d M i d d l e T r i a s s i c . N e o g o n d o l e l l a s p . ; 1 2 , lcwer; 1 3 , u p p e r v i e w ; import a n t Perrr,ian and Lower and M i d d l e T r i a s s i c g e n u s . S w e e t o g n a t h u s w h i t e i ( R h o d e s ) ; X60; Lower P e r m i a n s D-~~~ ecies.

15 16

17 18

--

19

20

-

21

22

-

23

24 - 25 26

21 28 29 30 31 32 - 33

T :e 3 s t z e t oq r.a t k od u c s u 1c c p 1i c a tn s ( V c u r q 7 u i c E , :iav: 1ey and ? : i ; l e r ) ; : : i d d i e Perr:.ian s c e c i e s . A n c h i g n a t h o e s p . ; X23; P e r m i a n and Lower T r i a s s i c genus. I d i o g n a t h o d u s a c u t u s E l l i s o n ; X29; Upper C a r b o n i f e r o u s genus. S t r e p t o g n a t h o d u s e c c e n t r i c u s E l l i s o n ; X29; 1 8 , u p y e r ; 19, l o w e r v i e w ; C a r b o n i f e r o u s g e n u s . Gnathodus p u n c t a t u s ( C o o p e r ) ; X29; 20, l a t e r a l ; 21, upper view; C a r b o n i f e r o u s genus. C a v u s g n a t h u s c o n v e x a R e x r o a d ; 22, l a t e r a l ; 2 3 , u p p e r v i e w ; Lower C a r b o n i f e r o u s s p e c i e s . M e s t o g n a t h u s beckmsnni B i s c h o f f ; 24, u p p e r ; 2 5 , l o w e r v i e w ; Lower C a r b o n i f e r o u s s p e c i e s . S i p h o n o d e l l a q u a d r u p l i c a t a ( B r o n s o n and P l e h l ) ; Lower Carboniferous species. P a l m a t o l e p i s p e r l o b a t a s c h i n d e w o l f i M u l l e r ; Upper Devonian s p e c i e s . S p a t h o g n a t h o d u s s t e i n h o r n e n s i s Z i e g l e r ; Lower Devonian species. I c r i o d u s w o s c h m i d t i Z i e g l e r ; Lower Devonian s p e c i e s . I c r i o d u s l a t e r i c r e s c e n s b i l a t e r i c r e s e n s Z i e q l e r ; Lowe r Devonian s p e c i e s ; g e n u s i m p o r t a n t t h r o u g h o u t Devonian. A n c y r o d e l l a l o b a t a ( B r a n s o n and M e h l ) ; Upper D e v o n i a n species. P o l y g n a t h u s p e n n a t a H i n d e ; 32, u p p e r ; 33, l o w e r v i e w ; genus i m p o r t a n t t h r o u q h o u t Devonian.

116 Siegenian

Species of Icriodus are the important Siegenian indicators, including 2. pesavis and f. latericrescens in North America and I.huddlei in Europe, Spathognathodus sulcatus is important in North American faunas but has not been found in Europe (Ziegler, 1971). Emsian As in the other Lower Devonian units, species of Icriodus and Spathognathodus. are the most important elements of the Emsian fauna, In addition, Polygnathus appears in the Emsian in both Europe and North America and is particularly important in the latter. Polygnathus dehiscens, Spathognathodus steinhornensis s-. and Icriodus species including huddlei and I. bilatericrescens are most important for the Emsian. In general, Emsian correlations of the Atlantic borderlands area (e.g., New York, Spain and France) are better understood than those of the earlier Lower Devonian units. Middle Devonian Eif elian Conodonts of this interval are well defined in Belgium, Spain, and Germany and can be differentiated into three zones (Ziegler, 1971). Jcriodus coringer marks the base of the Eifelian on both sides of the Atlantic (New York and Belgium) but is succeeded upward by Icriodus latericrescens n. subsp. A (Klapper, et al., 1971) in North America, a form that has not been found in Europe. Polygnathus species dominate the Atlantic borderland faunas and correlations are fiiirly secure, Givetian Icriodus and Polygnathus dominate the biostratigraphically important Givetian faunas. Specific differences are common between the European and North American section but sufficient common species (e.g., Polygnathus varcus) as well as associated megafossils allow some confidence in correlaticn. .The sections in Germany, Belgium and Spain and the New York section have become standrads. Some taxonomic problems with potentially significant Icriodus species are yet to be resolved (Ziegler, 1971, p. 258).

s.

.;

117

I

I

t

North America

Western Europe

Polygnothus vorcus

Polygnothus spp.

lcriodus obliquimorginotus

lcriodus spp.

-9 .4

P,

A *%

Q)

Polygnothus kockelionus C

Spothognothodus bidentotus

2

P o l y g n o t h u s spp.

i2 lcriodus corniger

1

Non- lotericrescid

c

Icriodus-Polygnothus

8

I. b. blloterlcrescens-S.

..0u, lu

I

-

steinhornensis -Polygnothus

Polygnathus foveolotus Spothognothodus exiguus exiguus Spothognothodus steinhornensis Polygnothus dehiscens lenzi Spothognothodus exiguus exiguus Spothognothodus steinhornensis

I

Polypnothus dehiscens lenzl I

1 :.

$ ..

$1

1

Spothognothodus sulcotus (lote forms)

I. huddlei curvicoudo

Icr iodus later icrescens n. su bsp. B lcriodus cf. I. n.sp.A.

I.huddlei huddlei

crj

I -

I

lcriodus huddlei curvicoudoto rectonguloris s.1.-ongustoldes

lcriodus pesovis -Spothog nothodus johnsoni - S.tronsitons

Ancyrodelloideslcriodus pesovis

Spothognothodus n. sp. C

lcriodus w.postwoschmidti

Spothognothodus n. sp. 0

lcriodus w. woschrnidti

lcriodus w.woschmidt1

C

.? C

.s

8-

Fig. 2 .

Conodont z o n a t i o n of the Lower and Middle Devonian.

118

Upper Devonian By a l m o s t any s t a n d a r d o f m e a s u r e , t h e h i g h p o i n t of conod o n t e v o l u t i o n w a s reached d u r i n g t h e L a t e Devonian.

More t h a n

1 0 0 0 names h a v e b e e n p r o p o s e d f o r L a t e D e v o n i a n form t a x a ,

t w i c e a s many a s f o r any o t h e r s i m i l a r i n t e r v a l and e v o l u t i o n was more r a p i d t h a n a t any o t h e r t i m e ( C l a r k , 1 9 7 2 ) .

A t least

1 2 0 " i n d e x s p e c i e s " h a v e b e e n r e c o g n i z e d f o r t h e Upper Devonian

and t h e d e t a i l e d z o n a t i o n r e c o g n i z e d f i r s t i n Germany h a s b e come a n i d e a l model f o r b i o s t r a t i g r a p h y and a w o r l d s t a n d a r d f o r conodonts ( Z i e g l e r , 1971) ( F i g . 3 ) . S u b d i v i s i o n o f t h e Upper Devonian i n t o F r a s n i a n and Famenn i a n s t a g e s o r i n t o ammonoid u n i t s f o r c l a s s i f i c a t i o n i s unn e c e s s a r y now b e c a u s e t h e c o n o d o n t z o n e s h a v e p r o v i d e d a d e t a i l e d standard t h a t can stand a l o n e .

S p e c i e s of P o l y g n a t h u s ,

A n c y r o d e l l a and A n c y r o g n a t h u s a r e t h e i m p o r t a n t e a r l y Upper Devonian s p e c i e s b u t t h e s e t a x a a r e r e p l a c e d by a l i t e r a l f l o o d of P a l m a t o l e p i s s p e c i e s t h a t form the- s t r u c t u r a l u n i t y of t h e Upper D e v o n i a n z o n a t i o n . b e d e t e r m i n e d i n much of

Ancestor-descendant. r e l a t i o n s h i p s can t h e zonation.

A few s p e c i e s o f S p a t h -

o g n a t h o d u s a n d P r o t o g n a t h o d u s a r e i m p o r t a n t f o r t h e l a t e Upper Devcnian f a u n a s . CARBONIFEROUS Introduction The m o s t c o m p l e t e Lower C a r b o n i f e r o u s ccjnodont f a u n a s a r e t h o s e r e c o g n i z e d i n Germany and t h e Upper M i s s i s s i p p i V a l l e y . The A t l a n t i c b o r d e r l a n d s Lower C a r b o n i f e r o u s s e q u e n c e s c o n t a i n f a u n a s t h a t , i n p a r t , c o r r e l a t e w i t h t h e German and M i s s i s s i p p i V a l l e y s e c t i o n s , b u t w h i c h h a v e d i f f e r e n c e s , as w e l l (Rhodes and A u s t i n , 1 9 7 1 ) .

These l a t t e r f a u n a s a r e from F r a n c e ,

B e l g i u m , S p a i n , I t a l y , N o r t h A f r i c a , B r i t a P n and I r e l a n d , f o r t h e e a s t e r n A t l a n t i c b o r d e r l a n d s and t h e c e n t r a l A p p a l a c h i a n s for the western borderlands, Upper C a r b o n i f e r o u s c o n o d o n t s a r e p o o r l y known. American f a m a s i n t h e c e n t r a l A D r a l a c h i a n s

North

( P e n n s y l v a n i a , Ohio

and West V i r g i n i a ) h a v e b e e n o b t a i n e d from a p p r o x i m a t e l y 5% o f t h e s e p r e d o m i n a n t l y non-marine

sequences (Lane e t a l . , 1 9 7 1 ) .

C e n t r a l and w e s t e r n N o r t h American s e q u e n c e s a r e more m a r i n e a n d , h e n c e , more c o m p l e t e . complete.

The E u r o p e a n s e c t i o n i s q u i t e i n -

Conodont f a u n a s from t h e e a r l y Upper C a r b o n i f e r o u s

119

I Protognathodus UPPER MIDDLE LOWER UPPER MIDDLE LOWER

Spathognathodus costatus Polygnathus st yr iacus Scaphignathus velifer

1

Palmatolepis marginifera Palmatolepis rhomboidea

I

P a Ima t o leD is cr e D id a

[

I Pal matolepis triangularis Palmatolepis gigas

I

A . triangularis

I

1

I UPPER Polyg nat hus asym metricus

I

I

LOWER UPPER LOWER UPPER LOWER UPPER MIDDLE LOWER UPPER MIDDLE LOWER UPPER MIDDLE LOWER

Schmidtognathus hermani Polygnathus cristatus

Figure 3 .

I I

MIDDLE LOWER LOWE RMOST UPPER LOWER

Conodont z o n a t i o n of t h e Upper D e v o n i a n .

I

I

120

of Belgium, France, Britain and Ireland, comprise the record. The relatively poor conodont record for the Upper Casboniferous is related to ecologic constraints that may have as their source the shifting continental plates that closed the "protoAtlantic" Ocean during this period of different continental elevations. Lower Carboniferous Tournaisian-Kinderhookian

These roughly correlatable Lower Carboniferous time-rock units are characterized by similar to identical species of Siphonodella in both Europe and Yorth America. The m l t i p l e Siphonodella zones in North America are not as well represented in Europe but are correlated with Spathognathodus and Polygnathus species that are present in both sections (Collinson g al. - , 1971) (Fig. 4 ) Visean-Valmeyeran These intervals are distinguished by a diverse fauna of Gnathodus, Bactrognathus, Taphrognathus, Apatognathus, and Cavusgnathus species in North America and many of the same species plus important Polygnathus, llestognathus and Scaliognathus in Europe. Correlation among the various European and North American sections is good. The British Avonian sequence, in particular, is easily correlatable witpi the Upper Mississippi Valley section (Rhodes and Austi.n, 1971; Collinson et al., 1971). Namurian-Chesterian Although the late Lower Carboniferous interval is incornplete in the British Avonian, tht German and Mississippi Valley sections appear complete. All are characterized by Gnathodus, the German and North American sections by Paragnathodus, Kladognathus and Streptognathodus. Upper Carboniferous Namurian-Morrowan The Belgium Namurian sequence contains the best eastern Atlantic fauna (Eiggins and Bouckaert, 1968). Gnathodus and Idiognathodus dominate the faunas in Belgium and species are at least similar to those in the Morrowan of North America. Because of the rather poor state of knowledge concerning Upper Pennsylvanian conodont biostratigraphy, few correlations exist

.

121

(Rhodes and Austin, 1971). Morrowan falmas are better known than others from the Upper Carboniferous, and Lane et al. (1971) have described Midcontinent species of Spathognathodus, Idiognathodus, and Gnathodus that define seven biostratigraphic units. The same species are recognized in western North America and the central Appalachians. ~

British Avonian

M i s s i s s i p p i Valley R e g i o n

C b

Streptognathodus unicornis

*\

L

s

Kladognathus-Cavusgnothus naviculus

9

Kladognathus primus G. bilineatus-Kladognathus mehli

Gnat hod us g i r t y i co I I i n son i

G.bilineatus-Cavusgnathus altus

Gnathodus mononodosus \

no conodonts Mestognath. beckmanni-Poly. bischoffi

G. antetexanus-Polygnathus lacinatus

Gnathodus texanus-Taphrognathus

Boctrognathus-~aphrognathus

-Gnathodus s e m i g l a b e r -

G. semiglaber-Pseudo.multistriatus

Pseudopolygnath. multistriatus

c

Spath.costatus costatus-

Siphonodella isosticha-S.cooperi

b

Spat h ,robustus- S .t rid ent at us

-2- Gnathodus delicatus -2 C

S.quadruplicata-S.crenulata

Siphonodella-Polygnathus inornatus

t’ Patrognathus vario bilisSpathognothodus plurnulus

Siphonodella duplicota Siphonodella sulcato

Figure 4 .

Conodont zonation of the Lower Carboniferous.

122

Post-Morrowan C a r b o n i f e r o u s T h i s Upper C a r b o n i f e r o u s i n t e r v a l i s o n e of t h e more poorl y d e f i n e d u n i t s b a s e d on c o n o d o n t s . Post-Morrowan f a u n a s a r e known i n Belgium ( W e s t p h a l i a n ) a1.d i n c e n t r a l and w e s t e r n N o r t h America.

F o r t h e most p a r t , G n a t h o d u s , A d e t o g n a t h u s ,

I d i o g n a t h o d u s and Anchignathodus d o m i n a t e t h e f a u n a and many of t h e s p e c i e s r a n g e t h r o u g h o u t t h e Upper C a r b o n i f e r o u s s e c t i o n (Fig. 5 ) . R a t e s of c o n o d o n t e v o l u t i o n d u r i n g most of t h e P a l e o z o i c a p p a r e n t l y were h i g h e r t h a n d u r i n g t h e L a t e C a r b o n i f e r o u s and t h e u n i f o r m c o n o d o n t t a x a of th3.s i n t e r v a l r e f l e c t t h i s .

An

a l t e r n a t i v e i d e a t o t h i s i s t h a t o u r c o n c e p t o f L a t e Carboni f e r o u s t i m e , p a r t i c u l a r l y i n t h e post-Morrowan

i n t e r v a l , nay

b e i n e r r o r and t h i s i n t e r v a l may r e p r e s e n t o n l y a p a r t of what 'is p r e s e n t l y t h o u g h t t o b e i n c l u d e d . Whatever t h e e x p l a n a t i o n , Upper C a r b o n i f e r o u s c o n o d o n t s a r p e a r t o b e l e s s d i v e r s e t h a n t h o s e of any o t h e r s i m i l a r P a l e o z o i c o r Trf-a s s i c i n t e r v a l . PERMIAN

Introduction Marine Permian s t r a t a i s r a r e i n t h e A t l a n t i c b o r d e r l a n d s . T h e r e i s a l i m i t e d s e c t i o n i n G r e e n l a n d and c o n s i d e r a b l y more i n t h e A r c t i c I s l a n d s and wester;, N o r t h A m e r i c a .

There i s

l i t t l e known of t h e s e c t i o n i n S o u t h America and A f r i c a b u t

f a i r l y good, i f i n c o m p l e t e , s e c t i o n s a r e found i n s o u t h e r n and n o r t h e r n Europe.

The Dutch-German Permian B a s i n s have Lower

P e r m i a n , a t l e a s t some of which i s m a r i n e , and Upper Permian ( Z e c h s t e i n ) i r ! some a b u n d a n c e .

The Z e c h s t e i n Sea may h a v e had

c o n s i d e r a b l e e x t e n t i n n o r t h e r n Europe (Thomas, 1 9 7 5 ) and t h e German s u r f a c e s e c t i o n s c o n t a i n Upper Permian f a u n a s . E a r l i e s t Permian c o n o d o n t s a r e known o n l y i n w e s t e r n North America

( C l a r k and Behnken, 1 9 7 1 ) b u t l a t e s t Permian f a u n a s a r e

known now i n K a s h m i r - P a k i s t a n

and p a r t s of t h e mid-East

as w e l l

a s w e s t e r n N o r t h America ( F i g . 6 ) . Lower Permian Sakmarian-Wolfcampian E a r l i e s t Permian c o n o d o n t s , c o r r e s p o n d i n g t o e a r l y Wolfcampian d e t e r m i n a t i o n s i n w e s t e r n N o r t h A m e r i c a , e s s e n t i a l l y a r e t h e same a s t h o s e of t h e L a t e C a r b o n i f e r o u s , i . e . , Gnathodus, I d i o g n a t l i o d u s , A d e t o g n a t h u s , e t c . ( C l a r k , 1 9 7 4 ) .

123

Anchignathodus typicalis

0

$

3-.

7 Neogondolella orientalis

Gnathodus,Adetognathus,

7 Neogondolella rosenkrantzi

Idiognothodus,Anchignothodus SPP

::I

Q Neogondolella serrata serrota Neostreptognathodus clinei ldiognothodus n sp A

8 9s

* I S S , 42 C

Q

Neostreptognathodus proyi Neostreptognathodus sulcoplicatus Neostreptognathodus pequopansis

ldiognathodus n o d u l i f e r u s ldiognathodus ellisonl

Fig, 5.

Conodont z o n a t i o n o f Fig. 6. t h e Upper C a r b o n i f e r o u s .

Conodont z o n a t i o n of t h e Permian.

A c r i s i s i n ccncdont e v o l u t i o n d u r i n g t h e E a r l y Permian pro-

duced a d r a m a t i c c h a n g e i n a l l y o u n g e r f a u n a s ( C l a r k , 1 9 7 2 ) . To d a t e , t h e p r e - c r i s i s

E a r l y Permihn f a u n a h a s o n l y been rep o r t e d from w e s t e r n N o r t h A m e r i c a . Younger E a r l y P e r m i a n c c n o d o n t s a r e known f r o m N o r t h and S o u t h A m e r i c a ( C l a r k . 1 9 7 4 ) and i n c l u d e S w e e t c g n a t h u s , N e o g o n d o l e l l a , A n c h i g n a t h o d u s , and Ellisonia. Artinskian-Leonardian Conodonts o f t h i s i n t e r v a l a r e d o m i n a t e d by s p e c i e s of Neostreptognathodus, a d e s c e n d a n t of t h e o l d e r Permian Sweetcgnathus.

The b e s t f a u n a s o f t h i s i n t e r v a l a r e from w e s t e r n

N o r t h America b u t some s o u t h e r n E u r o p e a n m a t e r i a l i s known. N e o g o n d o l e l l a s p e c i e s showing good r e l a t i o n s h i p s w i t h o l d e r Wclfcampian m a t e r i a l a r e u s e f u l f o s s i l s i n t h i s i n t e r v a l (Behnken, 1 9 7 5 ) . Upper P e r m i a n Guadalupian S p e c i e s of N e o g o n d o l e l l a , E l l i s o n i a and N e o s p a t h o d u s a r e t h e i m p o r t a n t c o n o d c n t s of t h L s i n t e r v a l .

Good s e q u e n c e s i n

w e s t e r n N o r t h America form t h e s t a n d a r d of r e f e r e n c e w h i c h h a s been c o r r e l a t e d w i t h n o r t h e r n E u r o p e a n and G r e e n l a n d f a u n a s . The e m e r g e n c e of N e o s p a t h o d u s and N e o g o n d o l e l l a a s e x c e l l e n t

124

i n d e x forms i n t h e G u a d a l u p i a n i s t h e b e g i n n i n g o f a t r e n d t h a t continues u n t i l the Triassic e x t i n c t i o n . Dzhulfian Youngest m a r i n e Permian s t r a t a a r e e x t r e m e l y r a r e and a r e unknown i n t h e A t l a n t i c b o r d e r l a n d s a r e a ( F u r n i s h , 1 9 7 3 ) . G r e e n l a n d c o n o d o n t s a p p e a r t o b e G u a d a l u p i a n a s do Z e c h s t e i n s p e c i m e n s from n o r t h e r n E u r o p e .

K a s h m i r , P a k i s t a n and T r a n s -

Caucasus areas have p r o d u c e d t h e o n l y p u b l i s h e d d a t a on l a t e s t Permian conodonts (Sweet, 1970, 1 9 7 3 ) .

L a t e s t Permian t a x a

probably are p r e s e n t i n undescribed s e c t i o n s i n t h e western U n i t e d S t a t e s , as w e l l . Latest Permian faunas c o n s i s t of Neogondolella s p e c i e s

i n t e r m e d i a t e b e t w e e n t h o s e o f t h e G u a d a l u p i a n and E a r l y T r i a s s i c , A n c h i g n a t h o d u s , and E l l i s o n i a s p e c i e s s i m i l a r t o b o t h Permian and T r i a s s i c t a x a .

I n f a c t , Sweet (1973) concluded

t h a t t h e l a t e s t Permian t a x a d i d n o t e x p e r i e n c e t h e PermoT r i a s s i c c r i s i s and a r e d i s t i n q u i s h e d o n l y b e c a u s e o f t h e i r s i m i l a r i t y t o E a r l y T r i a s s i c forms. TRIASSIC Lower T r i a s s i c E a r l i e s t T r i a s s i c c o n o d o n t s " r e n o t p r e s e n t l y known from t h e A t l a n t i c borderlands b u t should be p r e s e n t i n Greenland,

a t least.

The f a u n a s from Lower T r i a s s i c s t r a t a a r e w e l l

known i n w e s t e r n Pu'orth America and i n t h e S a l t Range and T'ransI n d u s Ranges o f West P a k i s t a n .

The d e t a i l e d z o n a t i o n o f t h e

Lower T r i a s s i c i n c l u d e s s p e c i e s of N e o g o n d o l e l l a and Neospatho-

g , evolutionary

descendants of Permian s p e c i e s , as w e l l a s

new forms s u c h a s Parachirognathus-Furnishius and P l a t y v i l l o sus (Sweet -

e t al., 1971).

The e a r l i e s t f a u n a i s t h e same a s

t h a t f o u n d i n l a t e s t P e r m i a n s t r a t a b u t by t h e m i d d l e p a r t o f t h e Lower T r i a s s i c t h e f a u n a s a r e u n i q u e l y T r i a s s i c .

Species

of E l l i s o n i a a r e m o s t common b u t a r e n o t a s s t r a t i g r a p h i c a l l y r e s t r i c t e d a s t h e N e o g o n d o l e l l a and Neospathodus s p e c i e s (Fig. 7 ) . Middle T r i a s s i c Plosher ( 1 9 7 3 ) r e c o g n i z e d t h r e e f a u n a l a s s o c i a t i o n s f o r t h e M i d d l e and Upper T r i a s s i c .

-

The f i r s t , t h e g l a d i o g o n d o l e l -

l i d group, has only been recognized i n t h e Alpine-Tethyas b e l t .

125

R hae t ia n

Conodonts present but not diagnostic Epigondolella bidentata

Norian

Epigondolella multidentata

I

Epigondolella abneptis

Paragondole Ila p o l yg n a t h ifor mis

Karnian Neospathodus new passensis Epigondolella mungoensis

Ladinian Neogondolella mombergensis Neogondolella constricta

An isia n Neogondolella r e g a l e I

I Spat h ia n

Griesbachian Figure 7.

I

Neospathodus timorensis Neogondolella jubata unnamed zone

Anchignathodus typicalis

Conodont zonation of t h e T r i a s s i c .

1

126

The second, a group dominated by Neogondolella, has been recognized on both sides of the Atlantic as has the third, the Epigondolella group. Mosher (1973) suggested that, in spite of Triassic continental separation, with the exception of group 1, the Middle and Upper Triassic conodorits were not seriously affected. Species of Keogondolella, (r;. constricta and N_. mombergensis) dominate the Middle Triassic fai;nas, The German, Spanish and northern Italy faunas are well known as well as those from western North America. In addition, species described from the Cameroons in West Africa apparently are widespread (e.g., Epigondolella nungoensis). Upper Triassic Upper Triassic faunas include genera whose stratigraphic value is well documented in earlier rocks, e.g., Neospathodus, Epigondolella, and Paragondolella. Distinctive species are widespread in Europe and North America, although the best faunas have been obtained from the Alpine region of Europe. These species represent the end of the conodcnt lineage and their extinction at the close of the Triassic marks the end of conodont b iostra tigraphy UPPER PALEOZOIC AND TRIASSIC C.)NODOKT EVOLUTION The biostratigraphlc application of conodonts throuqh this ~ 1 5 million 0 year interval is based largely on morrhologic modifications of specimens that are interpreted as ancestors

.

and descendants.

Thus, approximately a dozen genera and sever-

al times that number of species provide the framework of a very sound biostratigraphy (Fig. 8 ) . Species of Icriodus mark the base of the Devonian and their evolution throughout the Devonian provide nine or ten zones of great importance. Their range is overlapped by that of Polygnathus, a taxon that alpeared in the late Early Devonian and provided a dozen or so important Middle and Upper Devonian to Lower Carboniferous zones. The stratigraphic significance of these two genera is overshadowed by species of Palmatolepis that dominate the Upper Devonian and provided more than a dozen zones. The Carboniferous began wi.th new genera, including Siphonodella, a definite Polygnathus descendant,

127

Epigondolella eospothodus

I

I

I

I

whose species provide four or more Lower Carboniferous (and one Late Devonian) zones. Thus, three genera and their descendants (Icriodus,Polyqnathus-Siphonodella, and Palmatolepis) are the basis of the Devonian-earliest Carboniferous biostratigraphy (40-50 million years), This homogeneous biostratigraphy breaks down in the remainder of the Carboniferous and earliest Permian, and spe

tion of biostratigraphically in- such as Gnathodus, Cavusgnaportant genera from the thus, Adetognathus, IdiognaDevonian-Tr ia ssic thodus, and Streptognathodus are the basis of the biostratlgraphy. Polygnathus, one of the important Devonian genera, is also important for the Carboniferous, and may be ancestral to some of the other important Carboniferous forms. A marked change, recently described as a c0:iodont "crisic:", occurred in the Early Permian (Clark, 1972). All of the important Carboniferous species became extinct and all postEarly Permian conodonts can be traced to a handful of srecies that were obscure, to some extent, prior to the crisis. Thus, the Sweetognathus-Neostreptoqnathodus line provided five or so Lower Permian zones, and evolved from Anchignathodus, a less important Carboniferous genus that survived until Early Triassic. Also important was Neogondolella, a genus that provides approximately a dozen Permian and Triassic zones, and nay be related to the relatively unimportant Carboniferous genus Gondolella. Neospathodus was new in the Permian and provided species for eight or so Permian and Triassic zones. Neospathodus was ancestral to Epigondolella and Paragondolella plus several other important Triassic forms. This post-Early Permian interval apparently was a return to the honoqeneous biostrati-

.

128

graphy of the Devonian-earliest Carboniferous, and three genera, Sweetognathus, Neogondolella and Neospathodus were the ancestors of most of the later Permian and Triassic biostratigraphically important species. ATLANTIC BORDERLANDS ON A DRIFTING CRUST The present North Atlantic Ocean began forming ~ 1 8 0 - 2 0 0 m.y. ago as part of the Russian platform rotation (Ostenso and Wold, 1973). This produced the opening of the North-AtlanticLabrador Sea that has resulted ii, the present separation of North America from most of Europe. North America and most of central and northern Europe had been in fairly close positions since at least the Early Paleozoic when the Russian platform collided with the North American-Greenland plate, causing the Caledonian orogeny. The proximity of Nortkl America and Europe during the duration from Early Paleozcic to the Early Triassic has been portrayed in a series of maps by Smith g . (1973). Unfortunately, details necessary to unambiguously define precise paleogeographic details of North America and Europe during this interval are lacking, Relationship of the Southern Atlantic borderlands continents is better known and during this interval, South America and Africa formed a single mass, separation of which during the Early Mesozoic produced tkle present South Atlantic. Thus, the Late Devonian configuration of the present Atlantic borderland areas included a North AmericanEurope proximity and a "proto-Atlantic" separating North America-Europe from Africa and South America. Durinq the Carboniferous the African-South Amei-ican block approached the North American-Middle and Nocthern Europe block, destroying the "proto-Atlantic" and by the Permian and Triassic there was no major oceanic area separating a tenuously fused South AmericaAfrica-North America-Europe. The Triassic collision of the Russian platform with the Siberian platform formed the Eurasian continent and produced rotation that opened the North AtlanticLabrador Sea. If this can be accepted as a factual description of the Late Paleozoic-Triassic paleogeographic framework, Devonian to Early Triassic conodont faunas in North America and Europe might be expected to be more similar than faunas of the Late

129

Triassic because of the formation of the modern Atlantic Ocean that separated the areas during the Triassic. Similarly, Devonian and Carboniferous conodont faunas of North AmericaEurope and those of southern Europe-Africa and South America should be less similar when they were separated by a "protoAtlantic" during the Devonian an? Carboniferous than during the Permian and Early Triassic when the continents were together. Late Triassic faunas might be expected to reflect the separation related to formation of the modern Atlantic. This might be considered a working hypothesis in spite of the many difficulties of reconstructing continental positions and the relatively unknown ecologic requirements of conodonts. In order to test this hypothesis, at least in part, the similarity index for faunas at various times and geographic positions has been calculated. This has been done using the similarity coefficient 2w/a+b, where w = number of conodont taxa common to two cmtinents, and a + b = total number of species on both continents. This has been based on form taxa recorded in the Wisconsin I B M conodont catalogue for all intervals indicated, except the Permian. The Permian figures are based on natural or multielement species. Resulting figures should be comparable, at least. These comparisons have been made with the warning of Cook and Taylor (1975) in mind, These students have emphasized the dana-r of unequivocal acceptance of the idea that faunal similarity = geographic proximity. Other factors (e.g., thermocline barriers) must be considered. The results are tabulated in Table 1. Apparent immediately is the incompleteness of the data matrix for many of the areas that could be expected to test the hypothesis. That is, South America and Africa have a unique roll in Late Paleozoic and Triassic continental patterns but there is no conodont data for most of this time interval that can be used. Indeed, the lack of data may be taken to indicate adverse ecology during this interval, Nicoll (1975) has suggested that conodonts could not tolerate the cold water associated with Permian glaciation, at least for western Australia. A Permian paleolatitude of S O 0 6 5 O for this part of Australia may suggest temperature tolerances for conodonts of that time interval. The more complete European-North American data is not inconsistent with

130

c o n t i n e n t a l p a t t e r n s (Fig. 9 ) b u t t h e drop i n s i m i l a r i t y index of . 2 9 0 - .194 - ,191 as t h e A t l a n t i c formed d u r i n g t h e T r i a s s i c c a n n o t by i t s e l f b e c o n s i d e r e d of e x t r a o r d i n a r y s i g n i f i -

c a n c e . The European-North American d a t a r e f l e c t s C a r b o n i f e r o u s e c o l o g i c problems t h a t a r e n o t n e c e s s a r i l y r e l a t e d t o c o n t i n e n t a l p o s i t . i o n ( e . g . , V a l l e n t i n e and Moores, 1 9 7 2 ) .

Indices for

o t h e r a r e a s ( T a b l e 1) may r e f l e c t t h e need f o r more d a t a more t h a n t h e y d o t h e c o n f i r m a t i o n of s h i f t i n g p o s i t i o n of t h e L a t e P a l e o z o i c and T r i a s s i c A t l a n t i c b o r d e r l a n d s . I n a d d i t i o n t o t h e form-taxa

s i m i l a r i t y index, a similar-

i t y i n d e x b a s e d on name z o n a l s p e c i e s was c a l c u l a t e d ( T a b l e 2 ) . T h i s s i m i l a r i t y m a t r i x h a s many b u i l t i n b i a s e s , n o t t h e l e a s t i m p o r t a n t of which i s t h e f a c t t h a t t h e r e a s o n a t a x o n i s t h e f o r a z o n e , i s b a s e d on i t s w i d e s p r e a d o c c u r r e n c e ,

name-giver

Hence, any c a l c u l a t i o n b a s e d on z o n a l s p e c i e s c o u l d b e expect e d t o g i v e a h i g h e r d e g r e e of s i m i l a r i t y t h a n t h e c o m p a r i s o n of s i m i l a r i t y i n d i c e s b a s e d on t o t a l t a x a ( T a b l e 1 ) . T h i s i s c o n f i r m e d , b u t t h e much h i g h e r i n d e x numbers c a n b e a t t r i b u t e d t o t h e b i a s i n s e l e c t i o n of z o n a l s p e c i e s . This zonal s i m i l a r i t y index i s p l o t t e d i n Figure 1 0 f o r N o r t h A m e r i c a and E u r o p e .

Whether o r n o t t h e L a t e T r i a s s i c

dropoff i s due t o t h e s e p a r a t i o n of t h e c o n t i n e n t s d u r i n g t h a t interva.'; i s u n c e r t a i n .

Certainly, it i s not inconsistent with

t h e p l a t e - t e c t o n i c moc;el now p r o p o s e d .

C a r b o n i f e r o u s low v a l -

u e s p r o b a b l y r e f l e c t t h e w e l l known C a r b o n i f e r o u s e c o l o g i c c h a n g e s more t h a n c o n t i n e n t a l p r o x i m i t y .

'

U

DEVONIAN

L

U MISSISSIPPIAN

L

U

PENNSYLVANIAN

L

U

PERMIAN

L

M

U

TRIASSIC

DEVONIAN

CARBON- PERMIAN TRIASSIC IFEROUS

Fig. 9. P l o t of d i v e r s i t y i n d e x F i g . 10. P l o t of z o n a l s i m i of f o r m - s p e c i e s f o r Europe and l a r i t y i n d e x of f o r m - s p e c i e s f o r Europe and N o r t h America. North A m e r i c a .

131 ACKNOWLEDGMENTS T h i s s t u d y was made p o s s i b l e b y NSF G r a n t GA-40454.

J i m Gamber, U n i v e r s i t y o f W i s c o n s i n g r a d u a t e s t u d e n t , a i d e d i n s i m i l a r i t y i n d e x c a l c u l a t i o n and u p d a t i n g o f t h e I B M f o r m t a x a Ed L a n d i n g , U n i v e r s i t y of M i c h i c a n a r a d u a t e s t u -

catalogue.

d e n t , m a i n t a i n e d t h e I B M c a t a l o g u e a n d made some p r e l i m i n a r y calculations for .this study,

P a u l Dombrowski d r a f t e d t h e f i g -

u r e s a n d t h e m a n u s c r i p t was t y p e d by C a t h e r i n e M . Ward. REFERENCES Austin, R.

1 9 7 3 , M o d i f i c a t i o r i of t h e B r i t i s h A v o n i a n

L.,

c o n o d o n t z o n a t i o n and a r e a p p r a i s a l o f European D i n a n t i a n c o n o d o n t z o n a t i o n and c o r r e l a t i o n .

Ann.

SOC. Gdol.

B e l g i q u e , v . 9 6 , p . 523-532. 1 9 7 5 , L e o n a r d i a n and G u a d a l u p i a n ( P e r m i a n )

Behnken, F . H . ,

conodont b i o s t r a t i g r a p h y ted States. Clark, D.

49, p.

284-315.

1972, E a r l y Permian c r i s i s and i t s b e a r i n g on

L.,

Permo-Triassic Volume 1, p .

,

i n w e s t e r n a n d s o u t h w e s t e r n Uni-

Jour. Paleont. v.

c o n o d o n t taxonomy.

Geol. P a l a e o n t . ,

Sp.

147-158.

1 9 7 4 , F a c t o r s of E a r l y P e r m i a n c o n o d o n t p a l e o e c o -

l o g y i n Nevada.

,

Jour. Palecnt. v.

and Behnken, F . H . ,

g r a p h y of

t h e Permian.

48, p.

710-720.

1 9 7 1 , Conodonts and b i o s t r a t i -

Geol. S O C . A m e r i c a M e m .

127,

p . 415-439. Collinson, Charles,Rexroad, C. B.

and Thompson, T . L . ,

1971,

Conodont z o n a t i o n of t h e N o r t h American M i s s i s s i p p i a n . G e o l . SOC. America Mem. Cook, H . E . ,

and T a y l o r , M .

127, p. E.,

353-394.

1975, E a r l y P a l e o z o i c continen-

t a l m a r g i n s e d i m e n t a t i o n , t r i l o b i t e b i o f a c i e s , and t h e thermocline, western United States.

Geol.,

v.

3 , p . 559-

562. F u r n i s h , W. M . ,

1973, Permian S t a g e N a m e s ,

i n , The P e r m i a n and

T r i a s s i c S y s t e m s and t h e i r m u t u a l b o u n d a r y , e d . Logan a n d C a n a d i a n S O C . P e t r o l . G e o l . Mem. 2 , p .

Hills.

522-548.

H i g g i n s , A . C . and B o u c k a e r t , J . , 1 9 6 8 , Conodcnt s t r a t i g r a p h y and p a l a e o n t o l o g y of t b l e Namurian o f B e l g i u m .

Expl.

C a r t e s G e o l . e t M i n e r e s B e l g i q u e , Men. 10, 64 p . Klapper

,

G.

,

O r r , W.

Sandberg, C . A . K.,

,

Collinson, C.

Rickard, L. V . ,

,

H u d d l e , J. W .

Schumacher, D . ,

,

Seddon, G .

and

132

Uyeno, T. T . , stratigraphy. Lane, H. R . , G.

D.,

1 9 7 1 , N o r t h American Devcnian conodoxit b i o -

Geol. SOC. A m e r i c a M e m .

127, p.

285-316.

M e r r i l l , G . K . , S t r a k a , J . J . , 111, and W e b s t e r , 1 9 7 1 , N o r t h American P e n n s y l v a n i a n c o n o d o n t s t r a t i -

graphy.

G e o l . SOC. A m e r i c a Men. 1 2 7 , p . 395-414.

N i c o l l , R . S . , 1 9 7 5 , The e f f e c t of L a t e C a r b o n i f e r o u s - E a r l y P e r m i a n g l a c i a t i o n on t h e d i s t r i b u t i o n o f P e r m i a n conodonts i n A u s t r a l a s i a . V.

G e o l . SOC. America A b s t r a c t s ,

7 , p . 828-829.

O s t e n s o , N . A . a n d Wold, R . J . , 1 9 7 3 , A e r o m a g n e t i c e v i d e n c e f o r o r i g i n of A r c t i c Ocean B a s i n , i n , A r c t i c Geology, e d . M.

G.

Pitcher.

A s s o c . P e t r o l . Geol. M e m .

Amer.

1 9 , p.

506-516. Rhodes, F . H . T. and A u s t i n , R . L . , 1 9 7 1 , C a r b o n i f e r o u s cono d o n t f a u n a s of E u r o p e . G e o l . SOC. A m e r i c a M e m . 1 2 7 , p . 317-352. Sandberg, C . A. and Z i e g l e r , W . ,

1973, Refinement of s t a n d a r d

Upper Devonian c o n o d o n t z o n a t i o n b a s e d on s e c t i o n s i n Nevada a n d West Germany. 122, Smith, A. G . ,

G e o l . P a l a e o n t . , v . 7 , p . 97-

B r i d e n , J . C . and Drewry, G . E . ,

1973, Phanero-

z o i c w o r l d maps, i n Organisms and c o n t i n e n t s t h r o u g h t i m e , e d . N . F . Hughes. Palaeont. Assoc. Spec. Paper 1 2 , p.

1-42.

Sweet, W. C . ,

1 9 7 0 , Uppermost P e r m i a n and Lower T r i a s s i c

c o n o d o n t s o f t h e S a l t Range and T r a n s - I n d u s R a n g e s , West Pakistan.

,

Univ. K a r s a s S p e c . Pub. 4 , p . 207-275.

1973, L a t e Permian and E a r l y Triassic ccnodont

f a u n a s , i n , The P e r m i a n and T r i a s s i c S y s t e m s and t h e i r m u t u a l b o u n d a r y , e d . Logan a n d H i l l s . P e t r o l . Geol. Mem. Sweet, W.

C.,

2 , p. 630-646.

and B e r g s t r o m , S . Pl., 1 9 7 1 ,

conodont b i o s t r a t i g r a p h y .

C a n a d i a n Soc.

e.Symposium o n

G e o l . SOC. America Men. 1 2 7 ,

449 p .

,

Mosher , L . C .

Hasenmueller, W. A . , Triassic. Thomas, T . M . ,

,

C l a r k , D. L.

,

Collinson, J . W.

,

and

1 9 7 1 , Conodont b i o s t r a t i g r a p h y of t h e

G e o l . SOC. A m e r i c a M e m .

1 2 7 , p . 441-465.

1975, Search f o r hydrocarbons i n s h e l f areas of

N o r t h w e s t E u r o p e : P r o g r e s s and p r o s p e c t s .

Amer.

ASSOC.

133

Petrol. Geol. Bull., v. 59, p . 573-617. Vallentine, J. W. and Moores, E. M., 1972, Global tectonics and the fossil record. Jour. Geol., v , 80, p . 167-184. Ziegler, W., 1971, Conodont stratigraphy of the European Devonian. Geol. SOC. America Mem. 127, p . 227-284.

Table 1.

S i m i l a r i t y i n d e x f o r conodont f o r m s p e c i e s d u r i n g i n d i c a t e d t i m e a n d f o r d e s i g n a t e d g e o g r a p h y . ~-

U.

Dev

U. L. M i s s

Eu & NA

.348

.136

Eu ti Af

.268

.017

Eu

&

.249

.312

Eu

& Asia

.lo9

.071

Aus

Miss L.

.231

L. P e n n U. P e r m M. T r i Penn L. P e r m L. T r i U. T r i -~ _ _ _ _ _ 0 .019 .34 .37 -290 .194 .191

x

X

X

x

X

X

X

X

0

0

.57

-53

.239

X

X

X

0 .065

-088 X

.239

x = i n s u f f i c i e n t data

T a b l e 2. Z o n a l s i m i l a r i t y i n d e x f o r N o r t h America and E u r o p e . __._

Upper T r i a s s i c

.75

Middle T r i a s s i c

.85

Lower T r i a s s i c

-76

Upper P e r m i a n

.67

Lower P e r m i a n

.29

Upper C a r b o n i f e r o u s

.25

Lower C a r b o n i f e r o u s

.57

Upper Devonian

-89

Middle Devonian

.50

L o w e r Devonian

-60

.-

.021 X

.270

Perm

Dev

Carb

Tri

.

.348

.204

.355

-268

.004

.249

-078

x

.lo9

.077

-55

x

.225 .03 6 X

.191

135

Discussion D r . F. M.

Swain:

To what e x t e n t may f a c i e s c o n t r o l have p l a y e d

an i m p o r t a n t r o l e i n l a t e P a l e o z o i c - T r i a s s i c c o n o d o n t d i s t r i bution i n c o n t r a s t t o continental separation o r proximity? D.

Dr.

L. Clark:

Much of o u r r e s e a r c h d u r i n g t h e p a s t 7 y e a r s

h a s been r e l a t e d t o c o n o d o n t p a l e o e c o l o g y . e v i d e n c e t h a t c o n o d o n t s behaved

T h e r e i s good

much l i k e most o t h e r g r o u p s

of o r g a n i s m s : some were v e r y c l o s e l y r e l a t e d t o f a c i e s f a c t o r s , b u t many were p a r t of t h e p e l a g i c r e a l m .

The s i m i l a r -

i t y index c a l c u l a t i o n s d i d not consider f a c i e s c o n t r o l .

The

s i m p l i f i e d a s s u m p t i o n was t h a t a g r e a t e r s i m i l a r i t y may i n d i c a t e p r o x i m i t y of e n v i r o n m e n t s .

I t was r e c o g n i z e d t h a t geo-

g r a p h i c a l l y a d j a c e n t b u t d i f f e r e n t e n v i r o n m e n t s may s u p p o r t completely d i f f e r e n t taxa.

The c a l c u l a t i o n s f o r t h i s r e p o r t

w e r e made s i m p l y t o see i f t h e s i m i l a r i t y i n d e x f o r c o n o d o n t s (most o f which were n e k t o n o r p l a n k t o n ) c o r r e l a t e d w i t h t h e b e s t guesses f o r c o n t i n e n t a l s e p a r a t i o n s ) . I would answer t h e Holdsworth q u e s t i o n more s i m p l y

--

d i f f e r e n t i a l s o l u b i l i t y of a p a t i t e d u r i n g d i a g e n e s i s of c a r b o n a t e s (and c l a s t i c s ) h a s n o t been r e c o g n i z e d .

Only re-

worked c o n o d o n t s show p r e s e r v a t i o n a l problems and t h i s c a n be e x p l a i n e d more e a s i l y by t h i n g s o t h e r t h a n s o l u t i o n of c a l cium p h o s p h a t e . D r . M.

C.

Keen:

Could you comment on t h e s t a t u s of t h e cono-

d o n t s r e p o r t e d from t h e C r e t a c e o u s of W . A f r i c a ? C l a r k : The " C r e t a c e o u s " c o n o d o n t s from A f r i c a a r e p a r t o f t h e upper Middle T r i a s s i c f a u n a r e c o g n i z e d worldwide. F u r t h e r , most o f t h e c o n o d o n t e l e m e n t s from t h e A f r i c a n sample became e x t i n c t ( i n normal s e q u e n c e s ) b e f o r e t h e c l o s e of t h e T r i a s sic.

The same i s t r u e f o r t h e J a p a n e s e " J u r a s s i c " m a t e r i a l .

T h e r e a r e no unambiguous p o s t - T r i a s s i c c o n o d o n t s . Dr.

B. K . Holdsworth:

I s t h e r e any p o s s i b i l i t y t h a t a p p a r e n t

f a c i e s r e s t r i c t i o n of c o n o d o n t s c o u l d b e c o n n e c t e d w i t h d i f f e r e n c e s i n s u s c e p t i b i l i t y t o s o l u t i o n of p a r t i c u l a r forms during diagenesis? Clark:

To t h i s I would s a y t h a t a s f a r a s I know, t h e r e a r e no

n o t a b l e d i f f e r e n c e s i n r e l a t i v e s o l u b i l i t y of conodont s p e c i mens i n t h e s e d i m e n t s w e g e n e r a l l y work w i t h .

Under normal

c i r c u m s t a n c e s , t h e c o n o d o n t s a r e v e r y w e l l p r e s e r v e d and show

136

no i n d i c a t i o n s of b e i n g p a r t i a l l y d i s s o l v e d .

Accordingly, L

do n o t t h i n k t h a t s e l e c t i v e p r e s e r v a t i o n f o r t h a t r e a s o n , i f a t a l l p r e s e n t , i s l i k e l y t o be a problem.

One b i g problem

h a s , however, a p p e a r e d and it i n v o l v e s t h e l a b o r a t o r y p r e p a r a t i o n . U p t o r e c e n t l y , some l a b o r a t o r i e s were u s i n g monoc h l o r i c a c i d f o r p r e p a r a t i o n o f conodont samples b u t u n f o r t u n a t e l y , it h a s t u r n e d o u t t h a t when t r e a t e d w i t h t h i s a c i d f o r some t i m e , some forms were d i s s o l v e d and o t h e r u n a f f e c t e d , t h e r e b y producing b i a s e d f a u n a s as l a b o r a t o r y a r t i f a c t s . F o r t u n a t e l y , a s f a r a s I know, t h e s e e a r l y - d i s s o l v e d e l e m e n t s have n o t p l a y e d a n i m p o r t a n t r o l e i n t h e d i s c u s s i o n s of conod o n t biogeography and b i o s t r a t i g r a p h y .

137

NOTES ON PALEOZOIC ACRITARCHS FROM THE ATLANTIC MARGINS F. M. Swain University of Minnesota, Minneapolis, Minnesota; and University of Delaware, Newark, Delaware Abstract Stratigraphically useful acritarch assemblages of Atlantic margins have been described from Ordovician rocks of Europe and North Africa; Silurian of Europe, North Africa, and North America; Devonian of Europe, North and South America; Carboniferous of North America, Europe, and North Africa; and Permian of Europe, North Africa, and North America. Zusammenfassung Formationskundig, ndtzliche Versammlungen der Acritarchen von Atlantischen Rdnder sind von Ordovizischen Felsen des Europas und Nordafrikas; dem Silur des Europas, Nordafrikas und Nordamerikas; Devon des Europas,,Nord- und Siidamerikas: Karbon des Nordamerikas, Europas, und Nordafrikas; und dem Perm des Europas, Nordafrikas, und Nordamerikas beschreibt.

Introduction The following brief discussion will deal with a few selected acritarch assemblages from localities bordering the Atlantic Ocean, together with references that will hopefully guide the reader to additional studies on these useful microfossils. A specialist was not available to prepare an acritarch article for this volume and the present writer has depended completely on publications from which a few notes are presented herein. Cambrian A few acritarch assemblages have been recorded from Cambrian rocks but the writer has not reviewed the literature on them. Ordovician Acritarchs of Ordovician rocks of Europe and North Africa have been studied by Burmann (1968), Cramer (1964), Cramer &. (1974a, 1974b) , Deunff (1961, 1968) , Martin (1968), Vavrdovd (1965, 1972) , and Eisenack, et al. (1973). Cramer et al. (197433) recorded 10 species which they be-

138

l i e v e have s h o r t s t r a t i g r a p h i c r a n g e s from t h e l a t e A r e n i g i a n s h a l e s o f t h e T a d l a B a s i n o f Morocco: Vavrdovd 1 9 7 2 ( T e x t - f i g .

Aureotesta c l a t h r a t a

1-8), Morrocanium s i m p l e x C r a m e r ,

K a n e s , D i e z , and C h r i s t o p h e r , 1 9 7 4 , Neoveryhachium c a r m i n a e (Cramer, 1964) and r e l a t e d forms, P r i s c o t h e c a s i e m p r e p l i c a t a Cramer e t a l . ,

1 9 7 4 , Rugulidium microrugulatum ( M a r t i n , 1 9 6 8 ) ,

g. v a r i r u g u l a t u m C r a m e r , e t a l . , 1 9 7 4 , g.

al.,

1974 ( T e x t - f i g .

1-9),

angulatum C r a m e r e t a l . dre, 1946).

,

5.

s c a b r a t u m (Crarner, 1 9 6 4 ) ,

5.

G-

1974 , and Veryhachium l a i r d i (Def l a n -

Most o f t h e s p e c i e s a r e l a t e A r e n i g i a n t o e a r l y

Llanvirnian i n range but

late Arenigian age.

g.

s i e m p r e p l i c a t a i s of Tremadocian t o

S e v e r a l of t h e forms a l s o o c c u r i n Belgium,

northern Florida subsurface, Spain, Libya, Tunisia, Algeria, and S a u d i A r a b i a . I n a c o m p a r a t i v e s t u d y Cramer e t a l .

(1974a), seven late

Aren g i a n t o e a r l y L l a n v i r n i a n a c r i t a r c h s a l s o a r e b e l i e v e d t o have r e s t r i c t e d r a n g e s : 1-1)

fig. 1-2),

M_.

P i r e a d u b i a VavrdovA 1 9 7 2 ( T e x t - f i g .

Multiplicisphaeridium hoffmanensis C r a m e r e t a l .

.:

m o r o q u e n s e Cramer e t a l . 1974 ( T e x t - f i g .

r a y i i C r a m e r e t a l . 1974 ( T e x t - f i g .

C r a m e r e t a l . 1974 ( T e x t - f i g . et a l . 1974 ( T e x t - f i g . 1 - 6 ) . -

1-5)

,

(Text-

1-3),

1 - 4 ) , Oodium mordidum

Coryphidium e l e g a n s C r a m e r

P_. d u b i a h a s a l s o b e e n r e c o r d e d

from Bohemia, L i b y a a n d i n p r e s u m a b l y r e w o r k e d S i l u r i a n d e p o s -

i t s o f NW S p a i n . Other than t h e occurrences i n t h e r e l a t i v e l y undisturbed Ordovician rocks of northern F l o r i d a subsurface r e f e r r e d t o a b o v e , l i t t l e i s known o f O r d o v i c i a n a c r i t a r c h s o f t h e w e s t e r n margin of t h e A t l a n t i c Ocean. Silurian S t u d i e s of S i l u r i a n " h y s t r i c h o s p h e r e s "

( a c r i t a r c h s ) of t h e

E u r o p e a n A t l a n t i c m a r g i n s i n c l u d e t h o s e by E i s e n a c k ( 1 9 3 4 , 1 9 5 4 , 1 9 5 5 , 1 9 5 9 , 1 9 6 2 , 1 9 6 5 , 1 9 7 0 , 1 9 7 1 , 1 9 7 2 1 , Downie ( 1 9 5 9 , 1 9 6 3 ) , D e f l a n d r e ( 1 9 4 2 , 1 9 4 5 ) , Deunff

(1954) , C r a m e r (1964,

1 9 6 6 a , 1 9 6 6 b ) , Bachmann a n d Schmid ( 1 9 6 4 ) , M a r t i n ( 1 9 6 5 , 1 9 6 6 1 , Stockmans a n d W i l l i h r e ( 1 9 6 3 ) , a n d L i s t e r ( 1 9 7 0 ) . The L l a n d o v e r i a n V i s b y Marl o f t h e B a l t i c

(Gotland) con-

t a i n s a r i c h a c r i t a r c h assemblage with Multiplicisphaeridium s p p . a n d o t h e r f o r m s , many of w h i c h a l s o r a n g e i n t o t h e Wenlockian elsewhere (Eisenack,

2.& . ) .

139

An assemblage of acritarchs from the type Wenlockian Wenlock Shales of Wenlock, England comprises, among other longer ranging forms, 38 species or subspecies that Downie (1963) believed are confined to the Wenlockian. Several of the forms he cited, however, are now known to occur in older or younger deposits. Correlation of the Wenlockian assemblage with Wenlockian beds in France (Montagne Noire, Deflandre, 1945) and in the Baltic region (Eisenack, 2 . G.) is shown by certain of the species. Three assemblages are recognized by Downie in the type Wenlockian: Assemblage I of the Buildwas Beds, lower Wenlock, typified by Deunffia and Domasia,.Assemblage I1 of the middle Wenlock Coalbrookdale Beds with "Veryhachium" bulbiferum and "V_." elongatum as typical species; and Assemblage I11 of the upper Coalbrookdale and Tickhill Beds, upper Wenlock, have abundant Micrhystridium, leiofusid acritarchs and Multiplicisphaeridium granulatispinosum. The attempt has been made here to justify Downie's generic assignments with those of the acritarch catalogue of Eisenack et al. (1973) but some of Downie's species have not yet been listed in the published volume of the catalogue. Silurian acritarch floras are also known from the San Pedro and equivalent formations of northern Spain (Cramer 1966, 1967, 1968, 1970; Cramer and Diez 1968), Tarannonian and late Wenlockian? of Belgium (Martin, 1965, 1968); Tunisia and Libya (Hoffmeister, 1959; Cramer, 1970) and Shropshire England, (Lister, 1970) Silurian acritarchs of the western Atlantic margins have been recorded by Fisher (1953), and especially by Cramer and Diez de Cramer in a series of papers. A comprehensive examination of Silurian acritarchs of eastern North America was made by Cramer and Diez de Cramer (1972). Localities pertinent to the present volume are those in Maine, New York, Ontario, Pennsylvania, Virginia, Georgia, and Florida. The authors recognized five acritarch biofacies which they believe to be time-transgressive in the Silurian. The five, probably temperature-controlled biofacies are: (1) Neoveryhachium carminae (Text-fig. 12) ; ( 2 ) Domasia (Text-fig. 18) ; (3) Deunffia (Text-fig. 15) (with D. eisenacki subf acies) ; (4) Gloecocapsamorpha prisca , (5) Pulvinosphaeridium-

.

140

Estastra biofacies

( t o l e r a n t of warm c l i m a t e ) ; when t h e d i s -

t r i b u t i o n of t h e b i o f a c i e s i s p l o t t e d on a Pangaea a r r a n g e m e n t of t h e S i l u r i a n c o n t i n e n t s .

The a u t h o r s r e c o g n i z e s e v e r a l a c -

r i t a r c h realms a l l i n t h e S i l u r i a n s o u t h e r n hemisphere.

The

proposed t i m e - t r a n s g r e s s i v e d i s t r i b u t i o n o f t h e b i o f a c i e s t h r o u g h t h e S i l u r i a n p e r m i t s t h e a u t h o r s t o s u g g e s t a r a t e of c o n t i n e n t a l d r i f t of 3 c m . p e r y e a r d u r i n g t h e Wenlockian. The Gondwana p o l e , assumed t o b e t h e S o u t h P o l e of t h a t t i m e , p r o b a b l y l a y i n n o r t h e r n South A f r i c a .

An i n t e r e s t i n g s u g g e s t i o n is made that t h e l o n g - p r o b l e m a t i c a l e a r l y P a l e o z o i c b l o c k of

n o r t h e r n F l o r i d a s u b s u r f a c e o r i g i n a l l y l a y between B r a z i l and A f r i c a a s a s m a l l s l i v e r of c o n t i n e n t a l c r u s t , and s u b s e q u e n t l y drifted t o its present position. Cramer and D i e z d e Cramer l i s t t h e t o t a l c h r o n o s t r a t i g r a p h i c r a n g e s of s p e c i e s o r s p e c i e s - g r o u p s t h a t o c c u r abund a n t l y and more o r l e s s world-wide i n t h e S i l u r i a n , a s f o l l o w s : Neoveryhachium c a r m i n a e

(Text-fig. 1 2 )

,

middle e a r l y

L l a n d o v e r i a n ( g r a p t o l i t e zone 1 8 o r 1 9 ) t o b a s a l e a r l y Gedinnian. Domasia t r i s p i n o s a , m i d d l e e a r l y L l a n d o v e r i a n t o t o p Wenl o c k i a n ( 9 . z. 3 1 ) . Domasia e l o n g a t a ( T e x t - f i g .

18)

,

e a r l y l a t e Llandoverian

( 9 . z. 2 2 o r 2 3 ) t o t o p Wenlockian. Deunffia

(2.

monospinosa,

g.

eoramusculosa,

g.

furcata,

( T e x t - f i g . 1 5 ) , m i d d l e l a t e L l a n d o v e r i a n ( 9 . z. 23) t o t o p Wenlockian. D e u n f f i a e i s e n a c k i , e a r l y L u d l o v i a n ( 4 . z. 33 t o p ) t o end Ludlovian ( p o s t

-

g . z. 36)

Quadraditium fantasticum, l a t e e a r l y Llandoverian t o top S i l u r i a n . (Text-fig. 13) Duvernaysphaera a r a n a i d e s

(Text-fig.

14)

,

l a t e early

L l a n d o v e r i a n t o e a r l y Emsian. Baltisphaeridium denticulatum

(Text-fig.

16)

( s . 1 . ) b a s e of

S i l u r i a n ( 9 . z. 1 6 ) t o t o p G e d i n n i a n .

Eupoikilofusastriatifera ( T e x t - f i g . 17) , % ( w e l l s c u l p t u r e d f o r m s ) , b a s e of S i l u r i a n t o b a s a l e a r l y Gedinnian. Devonian A c o l l e c t i o n of a c r i t a r c h s from g r e e n s h a l e s of t h e San Pedro F o r m a t i o n , e a r l y G e d i n n i a n ? a t O b l a n c a , C a n t a b r i c Moun-

141

t a i n s , n o r t h e r n S p a i n was r e c o r d e d by C r a m e r ( 1 9 4 6 3 3 ) .

Twenty-

f i v e s p e c i e s o c c u r i n f r e q u e n c i e s g r e a t e r t h a n 1%, and t h e f o l lowing a r e p r e s e n t i n numbers g r e a t e r t h a n 1 0 % of t h e f a u n a : Veryhachium t r i s u l c u m D e u n f f , V_.

reductum D e u n f f , V_. c a r m i n a e

Cramer, M i c r h y s t r i d i u m s t e l l a t u m D e f l a n d r e , and M_. f r a g i l e Deflandre.

T h e r e a r e f i v e new s p e c i e s of L e i o f u s a .

five species,

L.

One o f , t h e

b e r n e s g a Cramer i s s t a t e d t o be w i d e l y d i s t r i -

buted i n t h e San P e d r o F o r m a t i o n of t h e C a n t a b r i c Mountains; t h e o t h e r f o u r a r e a p p a r e n t l y more r e s t r i c t e d i n d i s t r i b u t i o n . Some a d d i t i o n a l r e f e r e n c e s t o s t u d i e s of Devonian a c r i t a r c h s i n S p a i n and o t h e r p a r t s of w e s t e r n Europe and N o r t h A f r i c a i n c l u d e t h o s e of Cramer ( 1 9 6 6 a , 1 9 6 7 ) , J a r d i n g e t a l .

(1972) ,

Lanzoni and M a g l o i r e ( 1 9 6 9 ) , k u s c h e r ( 1 9 6 9 ) , and Stockmans and

W i l l i k r e (1960, 1 9 6 2 a , b , 1 9 6 9 ) . A s m a l l c o l l e c t i o n of a c r i t a r c h s from t h e e a r l y Devonian

of Uruguay, Department o f Durazno ( M a r t i n e z - M a c c h i a v e l l o , 1 9 6 8 ) , c o m p r i s e s 11 s p e c i e s , i n c l u d i n g a new s p e c i e s of Leoni-

e l l a and

s e v e r a l new s u b s p e c i e s of B a l t i s p h a e r i d i u m s i m p l e x

Stockmans and Willi\ere, Veryhachium l e g r a n d i S t . and W .

1. exasperatum D e u n f f .

,

and

The c o l l e c t i o n was o b t a i n e d from s h a l e s

t h a t have a l s o y i e l d e d sporomorphs. B r i t o ( 1 9 6 7 ) d e s c r i b e d b o t h S i l u r i a n and Devonian a c r i t a r c h s from t h e Maranhao B a s i n of n o r t h e r n B r a z i l .

The a c r i -

t a r c h - b e a r i n g s e q u e n c e o c c u r s w i t h i n a b o u t 2,500 meters of P a l e o z o i c r o c k s r a n g i n g from Cambro-Ordovician t o Permian i n age and l i t t o r a l - t o b a t h y a l - t o c o n t i n e n t a l i n l i t h o f a c i e s . The S i l u r i a n i s r e p r e s e n t e d by t h e I t a i m F o r m a t i o n ( m i d d l e and upper p a r t s ) .

Two p a l y n o l o g i c a l zones termed S ( p o o r l y d e v e l o p e d )

and T l i e i n t h e I t a i m F o r m a t i o n ; Zone T c o n t a i n s D a c t y l o f u s c a m a r a n h e n s i s B r i t o and S a n t o s ( T e x t - f i g . m u l l e r i B r i t o and S a n t o s . t o m i d d l e Devonian.

19)

,

The o v e r l y i n g P i c o s S h a l e i s e a r l y

Zones Lower Q and R a r e w i t h i n t h i s forma-

t i o n ; R has V e l i f e r i t e s tenuimarginatus B r i t o E v i t t i a sommeri B r i t o

and L e i o f u s a

(Text-fig. 18)

,

Cramer; Lower Q h a s T a s m a n i t e s s p . a f f .

(Text-fig.

211,

and T r i a n g u l i n a a l a r g a d a

2.

mourai Sommer,

L e i o f u s a b a c i l l u m Deunff and L. b r a z i l e n s i s B r i t o and S a n t o s (Text-fig. 2 0 ) . The lower and m i d d l e p a r t s of t h e o v e r l y i n g Cabesas F o r m a t i o n , m i d d l e Devonian a r e r e p r e s e n t e d by Upper Zone Q and Zone P ; Upper Zone Q h a s P s e u d o l u n u l i d e a i m p e r a t r i -

142

zensis Brito and Santos (Text-fig. 231, and Zone P has Maranhites sp., Duvernaysphaera radieta Brito (Text-fig. 22) as well as Polyedrixum sp., Netromorphitae and Chitinozoa. The upper Cabeqas Formation, middle to late Devonian has Maranhites brazilensis Brito, M_. mosesi (Sommer) (Text-fig.. 24) , and Pterospermopsis brazilensis Brito (Text-fig. 25), but not Chitinozoa or Netromorphitae. Other western Atlantic Devonian acritarch floras were described from Canada by Deunff (1955, 1961). Devonian sporomorphs are well developed around the Atlantic margins but are not dealt with herein. Carboniferous A major assemblage of acritarchs and prasinophycean algae was recorded from late Devonian and early Mississippian rocks in a bore hole near Barberton, northeastern Ohio, by Wicander (1974). He described 15 new genera and 56 new species from the late Devonian Cleveland and Chagrin Shales and the early Mississippian Bedford Shale. Of these the following were only recorded from the Mississippian: Cymatiosphaera velicarina Wicander (Text-fig. 26) , Conradidium firmamentum W. (Text-fig. 27), Diexallophasis absona W. (Text-fig. 2 8 ) , D. cuspidus W., Exilisphaeridium simplex W. (Text-fig. 29) , Multiplicisphaeridium verrucarum W. (Text-fig. 30) , Navifusa drosera W. (Textfig. 3 1 ) 1 , and Stellinium cristatum W. (Text-fig. 3 2 ) . Carboniferous acritarchs were described from north Africa (Algerian Sahara) by Lanzoni and Magloire (1969) and from Belgium by Stockmans and Williere (1966). There is also extensive literature on Carboniferous sporomorphs of the Atlantic margins not considered herein. Permian Acritarchs of particularly small size and included in Baltisphaeridium ('Text-fig. 33) , Micrhystidium (Text-fig. 34) , Verhyachium (Text-fig. 35) , and Leiofusa (Text-fig. 36) , were found in Lower Permian Marls of Yorkshire England (Wall and Downie 1962). A striking feature of the assemblages is a variable plexus of forms ranging between those of Veryhachium type and those of Micrhystridium type. The former are polygonal tests with as few as four processes and represent a Veryhachium? irregulare complex. The latter are small spherical forms with

--

143

as many as 20 spines of Micrhystridium type. Other Permian acritarchs are known from the Permian of Yugoslavia and from the Sahara (Jekhowsky, 1961), but in western Atlantic, only from Oklahoma (Wilson, 1960). References Bachmann, A., and Schmid, M., 1964. Mikrofossilien aus dem osterreichischen Silur., Verh. Geol. Bundesanst., H. 1, p. 63, 64. Brito, I. M., 1967. Silurian and Devonian acritarchs from Maranhso Basin, Brazil, Micropaleontology, v. 13, p. 473-482. Burmann, G., 1968. Diachrodien aus dem unteren Ordovizium, Palaont Abh., v. 2, no. 4, p. 639-652. Cramer, F. H., 1964a. Microplankton from three Paleozoic Formations in the Province of Le6n, NW Spain, Leidse Geol. Meded., v. 30, p. 253-361, p l s . 1-24. , 1964b. Some acritarchs from the San Pedro Formation (Gedinnien) of the Cantabric Mountains in Spain, Bull. SOC. belge G & o l . , v. 73, p. 33-38. I 1966a. Palynomorphs from the Siluro-Devonian boundary in NW Spain, Notas y Communs. I. G . M. EspaKa, v. 85, p. 71-82. I 1966b. Hoegispheres and other microfossils incertae sedia of the San Pedro Tormation (Siluro-Devonian boundary) near Valporquero, Leon, Spain, Notas y Communas, I. G. M. Espa’ia, v. 86, p. 75-94. I 1967. Palynology of Silurian and Devonian rocks of Northwest Spain, Bol., I. G. M. Espasa, no. 77, p. 225286. I 1968. Silurian Falynologic microfossils and paleolatitudes, Neues Jahrb. Geol. Palaont., Jg. 1968/10, p . 591-597. I 1970. Distribution of selected Silurian acritarchs, Rev. EspaEola Micropaleont., Num. Extraord. VI, p. 1-203. Cramer, F. H., Allan, B., Kanes, W . H., and Diez, M. d. C. R., 1974a. Upper Arenigian to lower Llanvirnian acritarchs from the subsurface of the Tadla Basin in Morocco. Palaeontographia Abt. B., v. 145, Lfg. 5, 6, p. 182-190. Cramer, F. H., and Diez de Cramer, M. d. C. R., 1968, Considerationes taxonomicas sobre las acritarcas del Silurico Medio y Superior del Norte de Espaxa. Primera Parte: Las acritarcas acantomorfiticas, Bol. I. G. M. Espaza, nr 79/6, p. 541-574. , 1972. North American Silurian palynofacies and their spatial arrangement: acritarchs, Palaontogr. Abh. B., v. 138, Lfg. 5-6, p. 107180. Cramer, F. H., Kanes, W. H., Diez, M. d. C. R., and Christopher, R. A., 197433. Early Ordovician acritarchs from the Tadla Basin of Morroco. Palaeontoqraphica, Abt. B., v. 146, Lft. 3-6, p. 57-64. Deflandre, G., 1942. Sur les Hystrichosphkres des calcaires siluriens de la Montagne Noire, Acad. Sci. Paris, C. R., 215, p. 475-476.

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, 1945. Microfossiles des calcaires siluriens de la Montagne Noire, Ann. Palgont., v. 31, p. 41-76. Deunff, J., 1954. Sur le microplancton du Gothlandien armoricain, SOC. Ggol. France, C. R . , Somm. v. 3,,p. 54, 55. , 1955. Un microplancton fossile Devonien a Hystrichosph'eres du continent Nord-Am&icain, Bull. Microscopie Appliqube, ser. 2, v. 5 , p. 138-149, pls. 1-4. , 1961a. Un microplancton 'a Hystrichosphbres dans le TrGmadoc du Sahara, Rev. Micropaleont., v. 4, p. 37-42. ., 1961Q. Quelques pre'cisions concernant les hystrichosphaeridees du Devonien du Canada, C. R. SOC. Geol. France, v. 8 , p. 216-218. , 1968. Arbusculidium,genre noveau d'Acritarche du Tremadocien marocain, C. R. Somm., Seances SOC. Geol. France, 1968, p. 101, 102. Downie, C., 1959. Hystrichospheres from the Silurian Wenlock Shale of England, Palaeontology, v. 2, p. 56-71. , 1963. "Hystrichospheres" (Acritarchs) and spores of the Wenlock Shales (Silurian) of Wenlock, England. Palaeontology, v. 6, pt: 4, p. 625-652, pls. 91, 92. Eisenack, A., 1934. Neue Mikrofossilien des baltischen Silurs I11 und neue Mikrofossilien des b8hmischen Silurs I, Palsont 2, V. 16, p. 52-76. , 1954. Hystrichospharen aus dem baltischen gotlandium, Senckenbergiana, v. 34,,p. 205-211. , 1959. Neotypen baltischen Silur-Hystrichosphxren und neue Arten, Palaeontographica ( A ) , v. 112, p. 193-211. , 1962. Einige Bemerkungen zu neuen Arbeiten Gber Hystrichosphsren, Neues Jahrb. Geol. Palaont., m.n., 1962, p. 52-101. . 1965. Mikrofossilien aus dem Silur Gotlands, Hystrichospharen, Problematika, Neues Jahrb. Geol. Palaont. Abh. 122, p. 257-274. , 1970. Mikrofossilien aus dem Silur Estlands und der Insel &el, Geol. Foren., Stockholm. Forh., v. 92, p. 302322. , 1971. Weitere Mikrofossilien aus dem Beyrichienkalk (Silur), Neues Jahrb. Geol. Palaont. mn., p. 449-460. , 1972. Chitinozoen und andere Mikrofossilien aus der Bohrung Leba, Pommern, Palaeontogr. Abt. A., v . 139, p. 64-87. Eisenack, A., Cramer, F. H. and Diez, M. d. C. R., 1973. Katalog der fossilen Dinoflagellaten, Hystrichosphsren und verwandten Mikrofossilien., v. 3, Acritarcha (I), E. Schweizbart'sche Verlagbuchlandlung, Nagele und Obermiller, Stuttgart, 1973, p. 1-1104. Fisher, D. W., 1953. A microflora of the Maplewood and Neagher Shales, Buffalo SOC. Nat. Sci., Bull. 21, p. 13-18. Hoffmeister, W. S., 1959. Silurian plant spores from Libya, Micropaleontology, v. 5, p. 331-334. Jardine', S., Combaz, A., Magloire, L., Peniguel, G., and Vachey, G., 1972. Acritarches du Silurien terminal et du D&vonien du Sahara AlgLrien, 2 . R. Sept. Congr. internat. Stratigr. Gebl. CarbonifLre, Krefeld 1971, v. 1, p. 295-310. Jekhowsky, B. de, 1961. Sur quelques hystricosphbres PermoTriasiques d'Europe et d'Afrique, Rev. Micropaleontologie, V. 3, p. 207-212, pls. 1, 2.

145 L a n z o n i , E . , and M a g l i o r e , L . , 1 9 6 9 . A s s o c i a t i o n s p a l y n o l o giques e t l e u r s a p p l i c a t i o n s s t r a f i g r a p h i q u e s dans le D ~ v o n i e n s u p g r i e u r e t C a r b o n i f & r e i n f e r i e u r d e Grand e r g Occid e n t a l ( S a h a r a A l g e r i e n ) , Rev. d e L ' I n s t i t u t F r a n q a i s du P e t r o l e , v . 2 4 , p . 441-468, p l s . 1 - 8 . L i s t e r , T . R . , 1 9 7 0 . A monograph of t h e A c r i t a r c h s and C h i t i nozoa from t h e Wenlock a n d Ludlow S e r i e s of t h e Ludlow and M i l l i c h o p e a r e a s , S h r o p s h i r e , P a l a e o n t o g r . S o c . Monographs, 1, p . 1 - 1 0 0 . M a r t i n , , F . , 1 9 6 5 . L e s a c r i t a r c h s du s o n d a g e d e l a b r a s s e r i e L u s t a K o r t r i j k ( C o u r t r a i ) ( S i l u r i e n b e l g e ) , B u l l . SOC. b e l g e G e o l . P a l . H y d r . , t . 7 4 , p . 351-400. , 1 9 6 8 . L e s A c r i t a r c h e s d e 1 ' 0 r d o v i c i e n e t du S i l u r i e n belges. Dgtermination e t v a l e u r s t r a t i g r a p h i q u e , I n s t . R o y . S c . N a t . ( 1 9 6 9 ) M e m . 1 6 0 , p . 1-175. M a r t i n e z - M a c h i a v e l l o , J . C . , 1968. Q u e l q u e s A c r i t a r c h e s d ' u n 4 c h a n t i l l o n du De'vonien i n f e ' r i e u r ( C o r d o b 6 s ) d p B l a n q u i l l o , D e p a r t e m e n t d e D u r a z n o , Uruguay, Rev. M i c r o p a l e o n t o l o g i e v . 11, n o . 2 , p . 77-84. Rauscher, R;, 1969. P r e s e n c e d ' u n e forme n o u v e l l e d ' A c r i t a r c h s d a n s l e Devonien d e Normandie, C . R . Acad. S c i . P a r i s , v . 268, s e r . D . , p . 34-36, p l . 1. S t o c k m a n s , F . , and W i l l i & r e , Y. , 1 9 6 0 . H y s t r i c C o s p h L r e s du Dgvonien b e l g e ( S o n d a g e d e 1 ' A s i l e d ' a l i e n e s a T o u r n a i ) , S e n c k . L e t h . , v . 4 , p . 1-11, p l s . 1, 2 . , 1 9 6 2 a . H y s t r i F h o s p h k r e s du DBvonien b e l g e (Sondage d e 1 ' A s i l e d ' a l i e n e s a T o u r n a i ) , B u l l . SOC. B e l g e G 6 0 1 . P a l e ' o n t . H y d r o l . , v . 7 1 , p . 41-77, D l S . 1, 2 . , 1 9 6 2 b . H y s t r i c h o s p h k r e s dy Devonien b e l g e (Sondage d e Wepion, B u l l . S O C . B e l g e Ggol. P a l e ' o n t . H y d r o l . , v . 7 1 , p . 83-89, p l s . 1, 2 . , 1 9 6 3 . H y s t r i c h o s p h g r e s ou mieux l e s A F r i t a r c h e s du S i l u r i e n b e l g e , Sondage d e l a b r a s s e r i e L u s t a C o u r t r a i ( K o r t r i j k ) , B u l l . S O C . B e l g . d e Ggol. , t . 7 1 , f a s c . 3 , p . 450-481, p l . 1-3 ( B r u s s e l s ) . , 1966. L e s a c r i t a r c h e s du D i n a n t i e n du S o n d a a e d e l ' a s i l e d ' a l i e n e s Tournai ( B e l c- r i -s u e ) ., B u l l . S O C . Belqe G e b l . v . 7 4 , p . 462-477, p l . .l. , 1 9 6 9 . . A c r i t a r c h e s du Fammenie n I n f g r i e u r , M e m . Acad. R . B e l g i q u e s , C 1 . S c i . , v . 3 8 , p . 1-63, p l s . 1-5. V a v r d o v i , m . , 1 9 6 5 . O r d o v i c i a n a c r i t a r c h e s from c e n t r a l Bohev . 4 0 , p . 351-357. mia, y e s t n i k U . U . G . , V a v r d o v a , M . , 1 9 7 2 . A c r i t a r c h s from K l a b a v a S h a l e s ( A r e n i g i a n ) , Vestnik U.U.G., v . 4 7 , p . 79-86. Wall, D . , and Downie, C . , 1 9 6 2 . P e r m i a n h y s t r i c h o s p h e r e s from B r i t a i n , P a l e o n t o l o g y , v . 5 , p t . 4 , p . 770-784, p l s . 1 1 2 - 1 1 4 . W i c a n d e r , E . R . , 1 9 7 4 . Upper Devonian-Lower M i s s i s s i p p i a n a c r i t a r c h s and p r a s i n o p h y c e a n a l g a e from O h i o , U.S.A., P a l a e o n t o g r a p h i c a , A b t . B . , v . 1 4 8 , L f g . 1 - 3 , p . 9-43, 1 9 p l s . W i l s o n , L . R . , 1 9 6 0 . A P e r m i a n h y s t r i c h o s p h a e r i d from Oklahoma, Okla. Geol. n o t e s , v . 2 0 , p . 7 , 1 7 0 .

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Text-figures 1. Pirea dubia Vavrdova, X495, late Arenigian to early Llanvirnian shales, Tadla Basin, Morocco (after Cramer et al., 1974) 2. Multiplicisphaeridium hoffmanensis Cramer, et al., X825, late Arenigian to early Llanvirnian, Tadla Basin, Morocco (after Cramer et al., 1974) 3 . ~~u~tip:icisphaeridiummaroquense Cramer, et al., X450, late Arenigian to early Llanvirnian, Tadla Basin, Morocco, (after Cramer et al., 1974) 4 . Multiplicisphaeridium rayii Cramer et al., X495, late Areni gian to early Llanvirnian, Tadla Basin, Morocco (after Cramer et al., 1974) 5 . Oodium mordidum Cramer et al., X900, late Arenigian to early Llanvirnian, Tadla Basin, Morocco (after Cramer al. , 1974) 6. Zryphidium elegans Cramer et al., X825, late Arenigian to early Llanvirnian, Tadla Basin, Morocco (after Cramer al., 1974) 7. mcostella perforata Cramer et al., X495, late Arenigian to early Llanvirnian, Tadla Basin, Florocco (after Cramer 5 al. , 1974) 8. Ereotesta clathrata Vavrdova, X495, late Arenigian, Tadla Basin, Morocco (after Cramer et al., 1974) 9. Rugulidium rugulatum Cramer et al., X495, late Arenigian, Tadla Basin, Morocco (after Cramer, et al., 1974) 10. Xcanthodiacrodium s p . , X495, late Arenigian, Tadla Basin, Morocca (after Cramer & al., 1974) 11. Polygonium gracile Vavrdoz, X825, late Arenigian, Tadla Basin, Morocco (after Cramer & al., 1974) 12. Neoveryhachium neocarminae C r a m e s two different specimens, X495, middle early Llandoverian to basal early Gedinnian, eastern U.S.A. (after Cramer and Diez de Cramer, 1972) 13. Quadriditium fantasticum Cramer, X495, late early Llandoverian to top Silurian, eastern U.S.A. (after Cramer and Diez de Cramer, 1972) 14. Duvernayosphaera aranaides Cramer, X495, late early Llandoverian to early Emsian, eastern U.S.A. (after Cramer and Diez de Cramer, 1972) 15. Deunffia furcata Cramer, X495, middle late Llandoverian to top Wenlockian, eastern U.S.A. (after Cramer and Diez de Cramer. 1972) 16. Eupoikilofusa striatifera stericula Cramer, X495, species ranqes from base of Silurian to basal early Gedinnian, eastern U.S.A. (after Cramer and. Die2 de CTamer, 1972) 17. Dactylofusa maranhensis Brit0 and Santos, X240, Itaim Formation, Silurian, Maranhao Basin, Brazil (after Brito, 1967) 18. Evittia sommeri Brito, X240, Picos Shale, early to middle Devonian, Maranhao Basin, Brazil (after Brito, 1967) 19. Baltisphaeridium denticulata indianae Cramer, X495, base Silurian to top Gedinnian (range of species) eastern U.S.A., (after Cramer and Diez de Cramer, 1972) 20. Leiofusa brazilensis Brito and Santos, X300, Picos Shale, early to middle Devonian, Maranhao Basin, Brazil (after Brito, 1967) 21. Veliferites tenuimarginatus Brito, X750, Picos Shale, early to middle Devonian, Maranhao Basin, Brazil (after Brito, 1967)

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22. Duvernayosphaera radiata Brito, X300, Cahecas Formation, middle Devonian, Maranhao Basin, Brazil (after Brito, 1967) 23. Pseudolunulidea imperatrizensis Brito and Santos, X240, Cabecas Formation, middle Devonian, Plaranhao Basin, Brazil (after Brito, 1967) 24. Maranhites mosesi (Sommer), X375, Cabecas Formation, middle Devonian, Plaranhao Basin, Brazil (after Brito, 1967) 25. Pterospermopsis brazilensis Brito, X240, Cabecas Formation, middle Devonian, Maranhao Basin, Brazil (after Brito, 1967) 26. Cymatiosphaera velicarina Wicander, X825, Bedford Shale, early Mississippian, Ohio (after Wicander, 1974) 27. Conradidium firmamentum Wicander, X525, Bedford Shale, early Mississippian, Ohio (after Wicander, 1974) 28. Diexallophasis absona Wicander, X750, Bedford Shale, early Mississippian, Ohio (after Vicander, 1974) 29. Exilisphaeridium simplex Wicander, X750, Bedford Shale, early Mississippian, Ohio (after Wicander, 1974) 30. Multi licis haeridium verrucanum Wicander, X712, Bedford Shale: earl: Mississippian, Ohio (after Wicander, 1974) 31. Navifusa drosera Wicander, X450, Bedford Shale, early Mississippian, Ohio (after Flicander, 1974) 32. Stellinium cristatum Flicander, X637, Bedford Shale, early Mississippian, Ohio (after Wicander, 1974) 33. Baltisphaeridium debilispinum Thlall and Downie, X750, Lower Permian Marl, Yorkshire , Enqland (after bJall and Downie, 1962) 34. Micrhystridium stellatum Deflandre, X750, Lower Permian Marl, Yorkshire, Fngland (after Val1 and Downie, 1962) 35. Veryhachium? irregulare Jekhowsky, X750, Lower Permian Marls, Yorkshire, England (after Wall and Downier 1962) 36. Leiofusa jurassica Cookson and Eisenack, X750, Lower Permian Marls, Yorkshire, England (after Wall and Downie, 1962) 37. Domasia elongata Downie, X1050, Buildwas Beds, early Wenlockian, Wenlock, England (after Eisenack et al., 1973)

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PALEOBIOGEOGRAPHY OF CHITINOZOA BY Donald W. Z a l u s k y Glassboro State College G l a s s b o r o , New J e r s e y 08028 Abstract B i o g e o g r a p h i c d i s t r i b u t i o n of O r d o v i c i a n t o S i l u r i a n Chit i n o z o a of t h e a n c i e n t A t l a n t i c b o r d e r l a n d s i s d i s c u s s e d . The c l a s s i f i c a t i o n s y s t e m f o l l o w e d i s t h a t of J a n s o n i u s (1970). The g e n u s C o n o c h i t i n a i s r e s t r i c t e d t o forms w i t h a mucro o r c o p u l a ; some forms d e s i g n a t e d C o n o c h i t i n a by p r e v i o u s a u t h o r s are a s s i g n e d t o E u c o n o c h i t i n a , t h e r e f o r e , C o n o c h i t i n a , s e n s u s t r i c t o , h a s r a r e l y b e e n r e p o r t e d from N o r t h America. The gen u s C y a t h o c h i t i n a i s s u b d i v i d e d i n t o two i n f o r m a l g r o u p s : Qa t h o c h i t i n a I which i n c l u d e s t h e c o n i c a l f o r m s , a n d , C y a t h o c h i t i n a I1 which i n c l u d e s t h e c y l i n d r i c a l forms. Cosmop o l i t a n o r p r o v i n c i a l g e n e r a and s p e c i e s are n o t e d . Rgsurne' La d i s t r i b u t i o n b i o g g o g r a p h i q u e d e s C h i t i n o z o a i r e s Ordov i c i e n s aux C h i t i n o z o a i r e s S i l u r i e n s d e s a n c i e n s c o n f i n z A t l a n t i q u e s est d i s c u t g e . Le systeme d e c l a s s i f i c a t i o n s u i v i e s t c e l u i d e J a n s o n i u s ( 1 9 7 0 ) . L e g e n r e C o n o c h i t i n a est l i m it; a u x formes c o n t e n a n t un mucro o u un c o p u l a ; c e r t a i n s f o r mes a t t r i b u g e s a u p a r a v a n t % C o n o c h i t i n a p a r q u e l q u e s a u t e u r s , s o n t a t t r i b u d e s 'a E u c o n o c h i t i n a , d o n c , C o n o c h i t i n a , s e n s u s t r i c t o , o n t 6 t 6 r a r e m e n t r a p p o r t 6 d e l ' h d r i q u e du Nord. L e g e n r e C y a t h o c h i t i n a se s u b d i v i s e e n deux g r o u p e s i n f o r m e l s : C y a t h o c h i t i n a I q u i comprend l e s formes c o n i q u e s , e t Cyathoc h i t i n a I1 q u i comprend l e s formes c y l i n d r i q u e s . D e s g e n r e s e t d e s e s p e c e s c o s m o p o l i t e s ou p r o v i n c i a u x s o n t n o t & . Introduction C h i t i n o z o a , d i s c o v e r e d i n S i l u r i a n Baltic g l a c i a l errat-

i c s by E i s e n a c k i n 1929, are now documented from a l l c o n t i n e n t s e x c e p t A n t a r t i c a i n t h e O r d o v i c i a n t h r o u g h t h e Devonian interval.

I n i t i a l f i n d s were g e n e r a l l y b l a c k and opaque and

were i l l u s t r a t e d o n l y as s i l h o u e t t e s , of well-preserved

Subsequent d i s c o v e r i e s

m a t e r i a l p r o v i d e d some i n f o r m a t i o n on i n t e r -

n a l s t r u c t u r e s and a d d i t i o n a l i n f o r m a t i o n on s u r f a c e ornamen-

152

tation.

I t i s now r e c o g n i z e d t h a t s p i n e s a n d o t h e r ornamen-

t a t i o n o r i g i n a t e from a n e x t e r n a l tegument o r p e r i d e r m which i s f r e q u e n t l y d e g r a d e d and l o s t more r e a d i l y t h a n t h e p r i n c i p l e w a l l l a y e r o r ectoderm. The p r i m a r y m o r p h o l o g i c a l f e a t u r e s u t i l i z e d i n c h i t i n o zoan taxonomic a s s i g n m e n t a r e g e n e r a l o v e r a l l s h a p e , p r e s e n c e o r a b s e n c e of s p i n e s , and o t h e r o r n a m e n t a t i o n .

Loss of t h e

p e r i d e r m g e n e r a l l y r e s u l t s i n t h e l o s s of a l l smaller s p i n e s , a l t h o u g h some g e n e r a p o s s e s s l a r g e r p e r i a b o r a l s p i n e s which may b e r e t a i n e d .

Undoubtedly t h i s h a s c a u s e d some c o n f u s i o n

a s many d e g r a d e d s p i n o u s forms t h e n m i m i c smooth forms of similar o v e r a l l shape, Chitinozoan i n v e s t i g a t i o n s have demonstrated t h a t C h i t i nozoa were g e o g r a p h i c a l l y w i d e s p r e a d and e v o l v e d r a p i d l y i n t h e O r d o v i c i a n t h r o u g h Devonian P e r i o d s t h e r e b y p r o v i d i n g t h e p o t e n t i a l f o r a n extremely u s e f u l c o r r e l a t i o n t o o l .

Work i n

p r o g r e s s and r e c e n t i n v e s t i g a t i o n s w i l l u n d o u b t e d l y c l a r i f y much of t h e taxonomic and b i o s t r a t i g r a p h i c c o n f u s i o n .

Recom-

mended i s t h e two volume work o f t h e Commission I n t e r n a t i o n a l e d e M i c r o f l o r e du P a l e o z o i q u e ( c i t e d i n b i b l i o g r a p h y ) f o r a l l C h i t i n o z o a r e s e a r c h p r i o r t o 1965.

Subsequent t o t h i s d a t e ,

i m p o r t a n t p u b l i c a t i o n s ( E i s e n a c k , 1968, 1970, 1971, 1 9 7 2 a , 1972b, 1973; Boneham and Masters, 1973; Cramer, 1966, 1968, 1969, 1973; Cramer and Cramer, 1 9 7 2 a , 1972b; J e n k i n s , 1967,

153

1969, 1 9 7 0 a , 1970b; L a u f e l d , 1967, 1974; Lange, 1967, 1974; Urban, 1 9 7 2 ; Urban and K l i n e , 1970; Urban and Newport, 1973; and o t h e r s ) h a v e p r o v i d e d a s u b s t a n t i a l d e g r e e of m a t u r i t y t o C h i t i n o z o a knowledge.

E a r l y w o r k e r s r e p o r t i n g f i r s t occur-

r e n c e s from a p a r t i c u l a r g e o g r a p h i c e n t i t y c o n t r i b u t e d much t o t h e e x t e n s i o n of t h e p a l e o b i o g e o g r a p h y o f C h i t i n o z o a b u t und o u b t e d l y f o r c e d some i d e n t i f i c a t i o n s d u e t o t h e r e a s o n s d i s cussed earlier.

I t i s hoped t h a t i n v e s t i g a t o r s i n o t h e r spe-

c i a l i t i e s e n c o u n t e r i n g c h i t i n o z o a n s i n t h e i r samples w i l l req u e s t t h e a s s i s t a n c e of c h i t i n o z o a n workers t o a v o i d i n v a l i d taxonomic a s s i g n m e n t s . The s t r a t i g r a p h i c r a n g e of C h i t i n o z o a i s c o n f i n e d t o t h e P a l e o z o i c b u t i s o n l y known w i t h some d e g r e e o f c e r t a i n t y i n t h e O r d o v i c i a n t h r o u g h Devonian i n t e r v a l .

I s o l a t e d Cambrian

o c c u r r e n c e s h a v e b e e n r e p o r t e d b u t are (1) d o u b t f u l c h i t i n o z o a n s , ( 2 ) found i n r o c k s whose Cambrian a g e is q u e s t i o n a b l e , o r (3) p o s s i b l y r e p r e s e n t s t r a t i g r a p h i c l e a k s .

C h i t i n o z o a n s have

b e e n r e p o r t e d p r e s e n t i n P a l e o z o i c r o c k s younger t h a n Devonian b u t g e n e r a l l y o n l y t h e i r p r e s e n c e w a s noted--forms identified or illustrated. t r a t e d well-preserved

were n o t

Tasch ( 1 9 7 3 ) , however, h a s i l l u s -

C h i t i n o z o a r e p r e s e n t i n g two new g e n e r a

from t h e Permian F o r t R i l e y Fm. of Kansas (USA), b u t h a s n o t published f u r t h e r d e t a i l s .

154

Taxonomic C o n s i d e r a t i o n s The genus C o n o c h i t i n a w a s r e c o g n i z e d as s o b r o a d l y def i n e d t h a t many similar though d i s t i n c t f o r m s had b e e n assigned therein.

A s emended by Taugourdeau (1 9 6 6 ), C o n o c h i t i n a

was r e s t r i c t e d t o e x c l u d e forms w i t h o u t a mucro o r c o n s p i c u o u s callus.

For t h e e x c l u d e d f o r m s , Taugourdeau e r e c t e d t h e g e n u s

Euconochitina. I t i s g e n e r a l l y c o n s i d e r e d t h a t most i f n o t a l l C h i t i n o -

zoa formed c h a i n s a l t h o u g h c h a i n l e n g t h must h a v e v a r i e d between and w i t h i n g e n e r a .

D e s m o c h i t i n i d s and r e l a t e d forms a r e

f r e q u e n t l y found i n s h o r t t o l o n g c h a i n s w h e r e a s o t h e r forms

a r e g e n e r a l l y found i s o l a t e d o r n o t i n f r e q u e n t l y i n c h a i n s of o n l y two o r t h r e e t e s t s a t t a c h e d o r a l p o l e t o a b o r a l p o l e . F r e q u e n t l y more o r l e s s d i s t i n c t c o n c e n t r i c c i r c l e s , t h e call u s , a r e found c e n t e r e d o n t h e a b o r a l p o l e of many g e n e r a , p r o b a b l y t h e r e s u l t of c h a i n forming.

T h e r e f o r e t h e "conspic-

uous" c a l l u s becomes a matter of i n d i v i d u a l judgement i n ass i g n i n g a form t o C o n o c h i t i n a o r t o E u c o n o c h i t i n a .

This auth-

o r r e l i e s p r i m a r i l y o n t h e p r e s e n c e of a mucro t o d i f f e r e n t i a t e forms f o r a s s i g n m e n t .

On t h i s b a s i s , most N o r t h American

forms p r e v i o u s l y a s s i g n e d t o C o n o c h i t i n a are c o n s i d e r e d t o b e members of E u c o n o c h i t i n a . "...Conochitina

J a n s o n i u s (1970, p. 803) s t a t e d ,

s e n s u s t r i c t 0 i s common i n the B a l t i c area,

b u t s o f a r n o t r e c o r d e d from North America."

A review o f t h e

155

p u b l i s h e d i l l u s t r a t i o n o f North American " c o n o c h i t i n i d s " d i s c l o s e s o n l y a few forms w i t h a mucro.

I l l u s t r a t i o n s of

c. -

m i c r a n c a n t h a ( C o l l i n s o n and Schwalb, 1955, P1. 2 , F i g . 20) and

C.

d a c t y l u s (Pl. 2 , F i g s . 16-19) e a c h show more o r l e s s c l e a r -

l y a mucro; f u r t h e r , i n t h e d i a g n o s i s t h e y d e s c r i b e t h e p r e s e n c e of a s m a l l p a p i l l a (mucro) f o r e a c h s p e c i e s .

Boneham and

Masters (1973) i l l u s t r a t e d a specimen of C . d a c t y l u s which p o s s e s s e s a mucro ( F i g . 3 , n o , 8 ) .

C. m i n n e s o t e n s i s

i s shown

t o have a " b a s a l p r o c e s s " by J e n k i n s (1969, P1. 3 , F i g s . 11-

12).

J e n k i n s (p. 1 5 ) i n r e f e r e n c e t o

5.

r o b u s t a n o t e d , "A few

specimens i n e a c h p o p u l a t i o n b e a r a s h o r t c y l i n d r i c a l o r d i s t a l l y t a p e r e d r o d - l i k e b a s a l p r o c e s s ( c o p u l a , E i s e n a c k , 1959; 'mucro,'

L a u f e l d , 1967) . . . . I t

With t h e s e e x c e p t i o n s as n o t e d above, C o n o c h i t i n a s e n s u s t r i c t o i s n o t a b l y scarce i n N o r t h America w h e r e a s Euconochi-

tina is

r a t h e r common.

P o s s i b l y c o n t i n u e d work w i l l s h e d more

l i g h t o n t h i s anomaly. I t i s n o t t h e a u t h o r ' s i n t e n t t o s u b s t i t u t e i n f o r m a l no-

m e n c l a t u r e , however, a u s e f u l p u r p o s e would b e s e r v e d i f a t t e n t i o n i s c a l l e d t o t h e g e n e r i c d e s c r i p t i o n of C y a t h o c h i t i n a , E i s e n a c k , 1955.

E i s e n a c k d e s c r i b e d t h i s genus as h a v i n g a

more o r less c y l i n d r i c a l n e c k and a c o n i c a l chamber.

Such i s

t h e o v e r a l l s h a p e found i n t h e d e s i g n a t e d t y p e s p e c i e s , C. campanulaeformis.

The d i s t i n g u i s h i n g c h a r a c t e r i s t i c of Cya-

156

t h o c h i t i n a i s t h e p e r i a b o r a l c a r i n a i n a s s o c i a t i o n w i t h t h e above mentioned s h a p e .

E i s e n a c k and o t h e r s have s u b s e q u e n t l y

i n c l u d e d w i t h i n C y a t h o c h i t i n a forms w i t h l i t t l e o r no f l e x u r e t o d i s t i n g u i s h t h e neck, o r , t h a t is, e s s e n t i a l l y c y l i n d r i c a l forms.

Without d e s i r i n g t o change t h e a f f i l i a t i o n t o t h i s ge-

nus, t h e author proposes t h a t i n v e s t i g a t o r s d e s i g n a t e those c y a t h o c h i t i n i d s p o s s e s s i n g e s s e n t i a l l y a c o n i c a l chamber and c y l i n d r i c a l n e c k as C y a t h o c h i t i n a I and t h o s e e s s e n t i a l l y cyl i n d r i c a l i n o v e r a l l s h a p e as C y a t h o c h i t i n a 11; f o r example,

C. c y l i n d r i c a 11.

T h i s a u t h o r b e l i e v e s s u c h a p r o c e d u r e may

s e r v e a u s e f u l p u r p o s e i n b o t h p h y l o g e n e t i c and p a l e o b i o g e o g r a p h i c a l d i s t r i b u t i o n s t u d i e s p a r t i c u l a r l y i n t h o s e cases where i l l u s t r a t i o n s do n o t accompany c h i t i n o z o a n f a u n a l l i s t s . P e r h a p s t h e b e s t example of how t h i s may b e a p p l i e d i s found on P l a t e VII, Vol. 1, The C h i t i n o z o a n (Combaz, e t a l . ,

1 9 6 7 ) w h e r e i n a l l s p e c i e s of C y a t h o c h i t i n a known t h r o u g h 1965 are i l l u s t r a t e d .

These s p e c i e s are c a t a g o r i z e d a s Type I o r

I1 i n T a b l e 1 of t h i s r e p o r t .

O f t h e 23 s p e c i e s and subspe-

c i e s i l l u s t r a t e d , 11 are Type I and 1 2 are Type 11.

a r e p r o v i n c i a l t o t h e Northwest Africa--2 One of t h e f o r m e r ,

C.

Ten forms

Type I, 8 Type 11.

i n f u n d i b u l i f o r m i s , Taugourdeau and d e

Jekhowsky, 1960, w a s q u e s t i o n a b l y a s s i g n e d t o C y a t h o c h i t i n a by Taugourdeau and d e Jekhowsky b e c a u s e i t d i d n o t p o s s e s s a n observable carina.

157

European p r o v i n c i a l forms i n c l u d e 4 Type I and 4 Type 11. The l a t t e r i n c l u d e C. c o n i c a , Taugourdeau, 1 9 6 1 , from t h e Aquitane (S.W.

F r a n c e ) and

2.

e l e n i t a e , Cramer, 1964 from t h e

a d j a c e n t area o f Northwest S p a i n .

The a c r i t a r c h and c h i t i n o -

zoan f a u n a of Northwest S p a i n h a v e b e e n d e s c r i b e d by Cramer (1966) as more c l o s e l y a l l i e d w i t h t h e S a h a r a n Fauna t h a n t h e Baltic.

C.

s t e n t o r and

C. s t r i a t a ,

t h e o t h e r two s p e c i e s of

Type 11, a r e u n u s u a l l y l a r g e s p e c i e s from t h e B a l t i c area o r i g i n a l l y d e s c r i b e d by E i s e n a c k (1937) i n t h e genus Conochit i n a and s u b s e q u e n t l y t r a n s f e r r e d t o C y a t h o c h i t i n a as i n c l u d e d s p e c i e s by E i s e n a c k i n 1955. Cosmopolitan s p e c i e s o c c u r r i n g i n two o r more c o n t i n e n t s c o n s i s t of 5 Type I i n c l u d i n g t h e r a t h e r u b i q u i t o u s c a l i x -

campanulaeformis-kuckersiana complex. I t would t h u s a p p e a r t h a t C y a t h o c h i t i n a I1 i s r e s t r i c t e d t o t h e p r e s e n t s o u t h e r n l a t i t u d e s i f t h e a t y p i c a l forms s t e n t o r and C. s t r i a t a a r e e x c l u d e d .

C.

Cyathochitina I appear

t o have a more c o s m o p o l i t a n d i s t r i b u t i o n w i t h some s p e c i e s res t r i c t e d t o a t r a n s i t i o n a l zone between t h e S a h a r a n and t h e B a l t i c faunas.

I n p a r t i c u l a r , forms c l o s e l y r e l a t e d t o

2.

campanulaeformis are p r e s e n t i n B a l t i c , S a h a r a n , and North American s t r a t a . T h i s somewhat r e s t r i c t e d example u t i l i z i n g o n l y cyathoc h i t i n i d s known p r i o r t o 1965 a p p e a r s t o h o l d w i t h r e s p e c t t o

158

post-1965 r e p o r t s o f c y a t h o c h i t i n i d o c c u r r e n c e s .

Excluding a

p o s s i b l y p r e m a t u r e r e s t r i c t i o n of t h i s genus a n o t a t i o n o f t y p e would s e r v e t o e l i c i t u s e f u l p a l e o b i o g e o g r a p h i c a n d phylogenetic information. T a b l e 1. P a l e o b i o g e o g r a p h i c d i s t r i b u t i o n of pre-1965 c y a t h o c h i t i n i d s , Type I and 11. C y a t h o c h i t i n a Eisenack, 1955 P r o v i n c i a l Forms NW A f r i c a

Europe

Type I1 I1 I1 I1 I1 I1 I I II I1

Species Type S p e c i e s alata I1 c o n i c a cylindrica I1 e l e n i t a e djadoensis I granulata elongata I hymenophora fistulosa I novempopulanica fusiformis I regnelli hymenophora n i g a r i c a I1 s t e n t o r ?infundibuliformis I1 s t r i a t a koumeidaens i s obtusa Cosmopolitan Forms

Type I I I

Species c a l i x (NW A f r i c a , B a l t i c ) campanulaeformis (NW A f r i c a , B a l t i c , N. America) d i s p a r (NW A f r i c a , B a l t i c ) d i s p a r v e r r u c a t a ( A q u i t a n e , N. America) k u c k e r s i a n a (NW A f r i c a , B a l t i c , N. America)

I I

Ordovician and S i l u r i a n Biogeography The a n a l y s i s of t h e p a l e o b i o g e o g r a p h y of C h i t i n o z o a i s a t p r e s e n t c o m p l i c a t e d by s e v e r a l f a c t o r s .

A decided tendency

f o r c h i t i n o z o a n s t o r e a c t t o as y e t unknown e n v i r o n m e n t a l f a c tors exacerbates the picture.

The s u d d e n d i s a p p e a r a n c e a n d

159

r e a p p e a r a n c e a t h i g h e r i n t e r v a l s by some s p e c i e s h a s b e e n d i s c u s s e d by Mannil (1972).

C r a m e r (1970) n o t e d t h e sudden d r a -

matic i n c r e a s e s i n narrow z o n e s ,

t

2 mm, c h a r a c t e r i z e d by o n l y

one o r two s p e c i e s , a phenomenon which h e compared t o a l g a l blooms.

Rapid d e c r e a s e s i n abundance w i t h o u t a c o n c o m i t a n t

change i n l i t h o l o g y have b e e n d e s c r i b e d by L a u f e l d (1967). C e r t a i n areas o f t h e w o r l d have emerged a s q u a s i - r e f e r e n c e s e c t i o n s f o r c h i t i n o z o a n s due t o t h e i n t e n s i v e work of o n e o r more i n d i v i d u a l s .

Foremost among t h e s e i s t h e B a l t i c

area as t h e r e s u l t o f E i s e n a c k ' s a c t i v i t y s p a n n i n g more t h a n f o u r decades.

Material o b t a i n e d from areas g r e a t l y removed

from t h e B a l t i c h a v e o f n e c e s s i t y have b e e n compared t o t h e h o s t o f s p e c i e s d e s c r i b e d by E i s e n a c k . A s o u t h e r n r e f e r e n c e f a u n a came i n t o b e i n g due p r i m a r i l y

t o t h e e f f o r t s o f Taugourdeau, and Taugourdeau and d e Jekhowsky.

Material from c o r e samples s p a n n i n g O r d o v i c i a n t h r o u g h

Devonian s t r a t a p e r m i t t e d Taugourdeau and d e Jekhowsky (1960) t o i d e n t i f y highty-four

s p e c i e s ( f o r t y - n i n e new) i n two new

g e n e r a and t e n known g e n e r a .

A t t h e t i m e o f t h i s work t h e

p r e c i s e a g e of t h e s t r a t a w a s i n d e f i n i t e .

Cramer ( 1 9 6 4 ) , 1966) r e p o r t e d on t h e o c c u r r e n c e of Chit i n o z o a i n S i l u r i a n s t r a t a o f Northwest S p a i n a d d i n g a n o t h e r assemblage f o r comparative purposes.

L a u f e l d (1967) r e p o r t e d

on t h e C a r a d o c i a n C h i t i n o z o a of S h r o p e s h i r e , Wales.

Andress,

160

Cramer, and G o l d s t e i n (1969) r e p o r t e d on O r d o v i c i a n and S i l u r i a n c h i t i n o z o a n s o b t a i n e d from t h r e e w e l l c o r e s i n F l o r i da. O t h e r s i g n i f i c a n t works o f i n t e r e s t h e r e i n c l u d e Cramer (1968), c h i t i n o z o a n f a u n a o f the Red Mountain FIIL ( S i l u r i a n ) of Alabama and L a u f e l d ' s (1974) e x t e n s i v e r e p o r t on t h e S i l u r i a n C h i t i n o z o a of G o t l a n d .

Although Oklahoma i s geo-

g r a p h i c a l l y removed from t h e p r e s e n t A t l a n t i c Ocean, r e p o r t s by J e n k i n s (1967, 1969) on C h i t i n o z o a o f t h e O r d o v i c i a n formations.

V i o l a L s . F e r n v a l e L s . and t h e S y l v a n S h a l e of Okla-

homa p r e s e n t i m p o r t a n t c o n s i d e r a t i o n s f o r p a l e o b i o g e o g r a p h i c distribution.

J e n k i n s ' c o n t r i b u t i o n s a r e enhanced by h i s p r e -

vious e x t e n s i v e experience w i t h Baltic faunas. The f o r e g o i n g c o n s t i t u t e t h e p r i m a r y r e p o r t s which h a v e c o n t r i b u t e d most t o t h e p r e s e n t knowledge of t h e O r d o v i c i a n S i l u r i a n c h i t i n o z o a n b i o g e o g r a p h i c d i s t r i b u t i o n of the p e r i p h e r a l areas o f t h e A t l a n t i c Ocean.

S o u t h American c h i t i n o -

zoan f a u n a s a r e p r e s e n t l y l i t t l e known and do n o t c o n s t i t u t e a r e f e r e n c e i n t h e s e n s e used h e r e .

Many a d d i t i o n a l r e p o r t s

( o v e r 300) c o v e r i n g t h i s r e g i o n and o t h e r s supplement t h o s e p r e v i o u s l y mentioned b u t f o r v a r i o u s r e a s o n s a r e n o t germane to t h i s discussion The p a l e o b i o g e o g r a p h i c p a t t e r n of c y a t h o c h i t i n i d s p r e v i o u s l y d i s c u s s e d i n d i c a t e s a n o r t h e r n o r "Baltic" c h i t i n o z o a n

161

p r o v i n c e and a s o u t h e r n o r "Saharan" p r o v i n c e w i t h some deg r e e of b o t h p r o v i n c i a l i s m and c o s m o p o l i t a n i s m .

The i n t e r -

v e n i n g boundary i s b l u r r e d a n d t h e boundary i t s e l f may b e t h e r e s u l t o f a l i m i t i n g environmental f a c t o r r a t h e r than a physical barrier.

I t i s l i k e l y t h a t d i r e c t communication between

t h e two p r o v i n c e s e x i s t e d i n some t i m e i n t e r v a l s d u r i n g t h e l o n g t i m e s p a n under c o n s i d e r a t i o n . The c h i t i n o z o a n f a u n a o f t h e O r d o v i c i a n S y l v a n S h a l e w a s c o n s i d e r e d by J e n k i n s (1970) t o b e r e l a t e d t o t h e B a l t i c f a u n a on t h e b a s i s o f s p e c i e s i n common which r e p r e s e n t e d twentyf i v e p e r c e n t of t h e twelve s p e c i e s i d e n t i f i e d i n t h e S y l v a n S p e c i e s i n common were C o n o c h i t i n a cactacea, 6. ele-

Shale

D. s c a b i o s a . gans Y Desmochitina minor and -

(1969

Previously, Jenkins

had found t h e V i o l a and F e r n v a l e Limestones (Ordovi-

c i a n , Oklahoma) t o c o n t a i n c o s m o p o l i t a n e l e m e n t s c o n s i s t i n g of e l e v e n p r e v i o u s l y d e s c r i b e d s p e c i e s , and n o t e d a s t r i k i n g r e s e m b l a n c e t o f a u n a s from t h e Cardoc-Ashgill of E s t o n i a , Sweden, B r i t a i n , and t h e O s t e r k a l k of t h e B a l t i c r e g i o n .

The

cosmopolitan s p e c i e s c o n s i s t e d of Angochitina c a p i l l a t a , C. w e s e n b e r g e n s i s , Conochitina miracantha, -

robusta,

C. m i n n e s o t e n s i s ,

9c h i t i n a -minor

C. h i r s u t a , C.

C y a t h o c h i t i n a k u c k e r s i a n a , Desmo-

D. l a t a , R h a b d o c h i t i n a u s i t a t a , and R.

turgida.

L a u f e l d (1967) c o n c l u d e d t h a t t h e C a r a d o c i a n C h i t i n o z o a from D a l a r n a Sweden show a s t r i k i n g r e s e m b l a n c e t o E s t o n i a n

162

f a u n a s o f e q u i v a l e n t a g e (p. 292, " . . . a s might b e expected.") and s u g g e s t e d s i m i l a r i t i e s , l i m i t e d by s p a r s e i n f o r m a t i o n i n t h e l i t e r a t u r e , w i t h f a u n a s from t h e e a s t e r n United S t a t e s . Study o f t h e S h r o p s h i r e Caradocian c h i t i n o z o a n fauna by J e n k i n s (1967) l e d him t o conclude t h a t B a l t i c f a u n a s were c l o s e l y comparable whereas Saharan f a u n a s were o n l y r e m o t e l y comparable, c o n t a i n i n g o n l y two s p e c i e s r e c o g n i z e d i n Shrops h i r e (Rhabdochitina magna and S i p h o n o c h i t i n a p e l l u c i d a ) . However, as J e n k i n s p o i n t e d o u t (p. 485), t h r e e a d d i t i o n a l s p e c i e s known from t h e O r d o v i c i a n of B r i t i a n and t h e B a l t i c

are i n c l u d e d i n a Range C h a r t of Saharan forms by B e n o i t and Taugourdeau (1961) a l t h o u g h n o t f i g u r e d o r d e s c r i b e d by them. The p r e s e n c e of C l a t h r o c h i t i n a i n s e v e r a l Saharan assemblages and i t s a b s e n c e i n S h r o p s h i r e is b e l i e v e d by J e n k i n s (p. 485) t o emphasize t h e d i f f e r e n c e s between t h e s e two f a u n a s .

Some-

what anomalous i s t h e o c c u r r e n c e of c h i t i n o z o a n s b e l o n g i n g t o t h e genus S i p h o n o c h i t i n a i n B r i t i a n and t h e Sahara b u t a b s e n t i n the Baltic. I n a comparative s t u d y of G o t l a n d i c and Saharan S i l u r i a n chitinozoans.

Taugourdeau and d e Jekhowsky (1964) found a

h i g h d e g r e e of a f f i n i t y between t h e two b u t n o t e d a t i m e l a g i n c e r t a i n cases i n which some forms appeared much e a r l i e r i n t h e Sahara.

T h i s t i m e l a g w a s a t t r i b u t e d t o t h e l a r g e migra-

t i o n d i s t a n c e involved.

The B a l t i c c h i t i n o z o a n s were found by

163

Taugourdeau and d e Jekhowsky t o g e n e r a l l y be l a r g e r t h a n Saharan forms p a r t i c u l a r l y Conochitina.

Desmochitinids

were

remarkably s i m i l a r and a n c r y o c h i t i n i d s appeared t o f o l l o w p a r a l l e l e v o l u t i o n a l t h o u g h t h e y were much more d i v e r s i f i e d i n t h e Saharan r e g i o n .

F i n e l y p i l o s e a n g o c h i t i n i d s were noted

t o be a b s e n t i n A f r i c a .

Saharan assemblages w e r e c o n s i d e r e d

by Taugourdeau and de Jekhowsky t o b e more v a r i e d and evolved than t h e i r European c o u n t e r p a r t s .

Cramer (1973) c o n s i d e r e d F l o r i d a S i l u r i a n c h i t i n o z o a n s t o be q u i t e similar t o e q u i v a l e n t material from P o r t u g u e s e Guinea. Laufeld (1974) i n c l u d e d w i t h i n t h e genus G o t l a n d o c h i t i n a , Laufeld, 1974, t h r e e p r e v i o u s l y d e s c r i b e d C h i t i n o z o a (AncyroA . milanenc h i t i n a a e q u o r i s , A n g o c h i t i n a c a l l a w a y e n s i s , and -

sis)

p e c u l i a r t o t h e n o r t h e r n t i e r of s t a t e s of t h e C e n t r a l

United S t a t e s .

T h i s genus h a s n o t been r e c o g n i z e d from t h e

"Saharan" p r o v i n c e . From t h e f o r e g o i n g , i t i s e v i d e n t some d e g r e e of provincialism e x i s t s i n Ordovician-Silurian chitinozoan faunas i n s p i t e of some cosmopolitan e l e m e n t s which g i v e s r i s e t o n o r t h e r n and s o u t h e r n p r o v i n c e s as h a s been demonstrated f o r o t h e r organisms.

The n o r t h e r n o r "Baltic" p r o v i n c e encompasses

l a n d s b o r d e r i n g on t h e p r e s e n t B a l t i c Sea, t h e B r i t i s h I s l e s , A n t i c o s t i I s l a n d , Ontario, t h e northern states of t h e Central

164

United S t a t e s and i n t o Oklahoma.

The s o u t h e r n o r "Saharan"

p r o v i n c e i n c l u d e s .the Northwest A f r i c a n r e g i o n , P o r t u g u e s e Guinea, Northwest S p a i n , a n d F l o r i d a .

The i n t e r v e n i n g b o r d e r

between t h e two p r o v i n c e s may b e t r a n s i t i o n a l , however, " B a l t i c " and "Saharan" a s s e m b l a g e s a r e d i s t i n g u i s h a b l e b a s e d

on t h e c h a r a c t e r of t h e f a u n a as w e l l as c o m p o s i t i o n . References Cited Andress, N. E . , Cramer, F. H . , and G o l d s t e i n , R. F., 1969. O r d o v i c i a n c h i t i n o z o a n s from F l o r i d a w e l l s a m p l e s : T r a n s a c t . Gulf C o a s t Assoc. Geol. S O C . , v. X I X . B e n o i t , A , , and Taugourdea, P . , 1961. S u r q u e l q u e s c h i t i n o z o a i r e s d e l ' o r d o v i c i e n du S a h a r a : i n s t . F r a n s a i s P g t r o l e Rev., v. 1 6 , p. 1403-1421, 2 f i g s . , 2 p l s . C o l l i n s o n , C . , and Schwalb, H . , 1955. North American Paleozoi c C h i t i n o z o a : I l l . Geol. S u r v e y , Rpt. I n v e s t . 1 8 6 , 31 p . , 12 f i g s . , 2 p l s . Combaz, A . , e t a l . , 1967. M i c r o f o s s i l e s o r g a n i q u e du p a l g o z o i q u e ; p t . 2 , l e s c h i t i n o z o a i r e s , morphographie: C e n t r e N a t i o n a l Recherche S c i . Ed., 4 2 . , 8 f i g s . , 5 p l s . Cramer, F. H . , 1964. M i c r o p l a n k t o n from t h r e e P a l e o z o i c f o r m a t i o n s i n the P r o v i n c e o f Leon (NW-Spain): L e i d s e Geol. Mededel., v. 30, p . 253-261, 56 f i g s . , 24 p l s . , 1966. C h i t i n o z o a n s of a c o m p o s i t e s e c t i o n of upper L l a n d o v e r i a n t o b a s a l l o w e r G e d i n n i a n s e d i m e n t s i n n o r t h e r n Leon, S p a i n ; a p r e l i m i n a r y r e p o r t : S O C . Belg. G e o l o g i e B u l l . , v. 75, p . 69-146, 7 f i g s . , 5 p l s . , 1968a. C o n s i d e r a t i o n s p a l g o g e b g r a p h i q u e s 'a p r o p o s d ' u n e a s s o c i a t i o n d e m i c r o p l a n c t o n t e s d e l a se'rie g o t h l a n d i e n n e d e Birmingham ( A l a . , USA): SOC. Geol. F r a n c e B u l l . , ser. 7 , v. 1 0 , p. 126-131, 1 f i g . , 1969. P o s s i b l e i m p l i c a t i o n s f o r S i l u r i a n pal e o g e o g r a p h y from p h y t o p l a n c t o n a s s e m b l a g e s o f t h e Rose H i l l and T u s c a r o r a F o r m a t i o n s o f Pa.: J o u r . P a l e o n . , v. 43, p . 485-491, 2 f i g s . , p l . 70. , 1973. Middle and Upper S i l u r i a n c h i t i n o z o a n s u c c e s s i o n i n F l o r i d a s u b s u r f a c e : J o u r . P a l e o n . , v. 47, p . 279-288, 2 f i g s . , 2 p l s . Cramer, F. H . , and Diez d e Cramer, C. R . , 1972. S u b s u r f a c e s e c t i o n from P o r t u g u e s e Guinea d a t e d by palynomorphs as Midd l e S i l u r i a n : Am, Assoc. P e t r o l e u m G e o l o g i s t s B u l l . , v. 56,

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p. 2271-2272, 1 f i g . E i s e n a c k , A , , 1937. Neue M i k r o f o s s i l i e n d e s b a l t i s c h e n S i l u r s , I V : P a l a e o n t . Z e i t s c h r . , v. 1 9 , p. 217-243, 22 f i g s . , p l s . 15, 16. , 1955. Neue C h i t i n o z o e n a u s dem S i l u r d e s Baltikums und dem Devon d e r E i f e l : S e n c k e n b e r g i a n a L e t h a e a , v. 36, p. 311-319, 3 f i g s . , 1 p l . , 1968. h e r C h i t i n o z o e n d e s b a l t i s c h e n G e b i e t e s : P a l a e o n t o g r a p h i c a , Abt. A, v. 131, p. 137-198, 1 3 f i g s . , p l s . 24-32. , 1970. M i k r o f o s s i l i e n a u s dem S i l u r E s t l a n d s und d e r I n s e l Oesel: Geol. Foren. Stockholm F o r h . , v. 9 2 , p. 302-322, 7 f i g s . , 1971. Weitere M i k r o f o s s i l i e n a u s dem Beyrichi e n k a l k ( S i l u r ) : Neues J a h r b . G e o l o g i e u. P a l a e o n t o l o g i e Monatsh., p. 449-460, 34 f i g s . , 1972a. C h i t i n o z o e n und a n d e r e M i k r o f o s s i l i e n a u s d e r Bohrung Leba, Pommern: P a l a e o n t o g r a p h i c a , Abt. A , v. 139, p. 64-87, 6 f i g s . , p l s . 16-20. , 1972b. B e i t r a g e z u r Chitinozoen-Forschung: P a l a e o n t o g r a p h i c a , Abt. A . v. 1 4 0 , p . 117-130, 1 f i g . , p l s . 32-37. , 1973. K l e i n o r g a n i s m e n a l s Z e r s t o e r e r s a e u r e f e s ter o r g a n i s c h e r S u b s t a n z e n und von B i o p h o s p h a t e n : P a l e o n t . Z e i t s c h . , v. 47, p. 8-16, 2 p l s . J a n s o n i u s , J a n , 1964. Morphology and c l a s s i f i c a t i o n o f some C h i t i n o z o a : Canadian P e t r o l e u m Geology B u l l . , v. 1 2 , p. 901-918, 2 f i g s . , 2 p l s . , 1967. S y s t e m a t i c s o f t h e C h i t i n o z o a : Rev. P a l e o b o t a n y and P a l y n o l o g y , v. 1, p. 345-360, 2 f i g s . , 1 p l . , 1970. C l a s s i f i c a t i o n and s t r a t i g r a p h i c a p p l i c a t i o n of C h i t i n o z o a : J o u r . P a l e o n t o l o g y , v. 43, p . 889. J e n k i n s , W. A. M . , 1967, O r d o v i c i a n C h i t i n o z o a from Shrops h i r e : P a l e o n t o l o g y , v. 1 0 , p. 436-488, 1 2 f i g s . , p l s . 6875. , 1969. C h i t i n o z o a from t h e O r d o v i c i a n : V i o l a and F e r n v a l e L i m e s t o n e s o f t h e A r b u c k l e Mountains Oklahoma: P a l a e o n t . Assoc. Spec. P a p e r s P a l a e o n t o l o g y 5, 44 p . , 1 0 f i g s . , 9 p l s . , 1970. C h i t i n o z o a from t h e O r d o v i c i a n S y l v a n S h a l e of t h e A r b u c k l e Mountains, Oklahoma: P a l e o n t o l o g y , v. 1 3 , p. 261-288, 7 f i g s . , p l s . 47-51. Lange, F. W . , 1967. S u b d i v i s a o b i o e s t r a t i g r a f i c a e r i v i s a o d a c o l u n a Siluro-Devoniana d a b a s i a do b a i x o Amazonas: s i m p o s i o s o b r e a B i o t a Amazonica A t l a s , v. 1, p. 215-326, 4 f i g s . , 12 p l s .

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L a u f e l d , Sven, 1967. C a r a d o c i a n C h i t i n o z o a from D a l a r n a , Sweden: Geol. Foren. Stockholm F o r h . , v. 8 9 , p. 275-349, 34 f i g s . , 1974. S i l u r i a n C h i t i n o z o a from G o t l a n d , Foss i l s and S t r a t a , no. 5 , p . 1-128. Mannil, R., 1972. The z o n a l d i s t r i b u t i o n of c h i t i n o z o a n s i n t h e O r d o v i c i a n o f t h e East B a l t i c area. I n t . Geol. Congr. 2 4 t h Sess., S e c t . 7, 569-571. Tasch, P a u l , 1973. P a l e o b i o l o g y o f t h e I n v e r t e b r a t e s : John Wiley and Sons, I e c . , New York, 923 p. Taugourdeau, P h i l i p p e , 1961. C h i t i n o z o a i r e s du s i l u r i e n d ' A q u i t a i n e : Rev. M i c r o p a l g o n t o l o g i e , v. 4 , p . 135-154, 8 figs., 6 pls. , 1966. L e s c h i t i n o z o a i r e s : t e c h n i q u e s d ' g t u d e s , m o r p h o l o g i e e t c l a s s i f i c a t i o n : SOC. Geol. F r a n c e Mem., n. s e r . , v. 45, mem. 1 0 4 , 64 p . , 4 p l s . Tougourdeau, P h i l i p p e , and Jekhowsky, Benjamen, d e , 1960. Repartition et description des chitinozoaires silur-devonien d e l a C.F.P.A. e t d e d e q u e l q u e s s o n d a g e s d e l a C.R.E.P.S., l a S.N. Repal a u S a h a r a : I n s t . F r a n s a i s P g t r o l e Rev., v. 1 5 , p. 1199-1260, 1 9 f i g s . , 13 p l s . , 1964. C h i t i n o z o a i r e s S i l u r i e n s d e G o t l a n d ; comparison avec l e s Formes S a h a r i e n n e s , I n s t . F r a n f a i s P g t r o l e , v. 1 9 , p. 845870. et _ a1' 9 1967. M i c r o f o s s i l e s o r g a n i q u e s Taugourdeau, P h i l i p p e , d e palGozoique, pt,. 1; les c h i t i n o z o a i r e s ; a n a l y s e b i b l i o g r a p h i q u e i l l u s t r e e : C e n t r e N a t i o n a l Recherche S c i . Ed., 96 p . , 4 f i g . , 11 p l s . Umnova, N . , 1973. Methods of I n v e s t i g a t i o n , U s e of I n f a r e d L i g h t f o r t h e S t u d y o f C h i t i n o z o a : P a l e o n t . J o r . , 1973, no. 3, p. 394-400. Urban, J . B . , 1 9 7 2 , A r e e x a m i n a t i o n o f C h i t i n o z o a from t h e Cedar V a l l e y F o r m a t i o n o f Iowa w i t h o b s e r v a t i o n s o n t h e i r morphology and d i s t r i b u t i o n : B u l l s . Am. P a l e o n t o l o g y , v. 63, no. 275, p. 1-43, 9 f i g s . , 8 p l s . Urban, J. B . , and K l i n e , J . E . , 1970. C h i t i n o z o a of t h e Cedar C i t y F o r m a t i o n , Middle Devonian of M i s s o u r i : J o u r . P a l e o n t o l o g y , v. 44, p. 69-76, 2 f i g s . , p l . 18. Urban, J. B . , and Newport, R. L . , 1973. C h i t i n o z o a o f t h e W a p s i p i n i c o n (Middle Devonian) of Iowa: M i c r o p a l e o n t o l o g y , v. 1 9 , p . 239-246, 2 f i g s . , 2 p l s .

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P A L E O Z O I C RAD IOLARIA : STRAT IGRP.PH IC DISTRIBUTION I PI ATLANTIC RORDF. P,LAI!DS B . K . H O L D S W O R T H , D e p a r t m e n t o f G e o l o g y , The U n i v e r s i t y , K e e l e ST5 5BG, E n g l a n d ABSTRACT: A few well-preserved, well-dated faunas suggest t h a t Ordovician, S i l u r i a n , Devonian and Carboniferous Systems rlay each possess c h a r a c t e r i s t i c Radiolaria populations, with a major change i n fauna occurring i n t h e Uoper S i l u r i a n or Lower Devbnian. Known Paleozoic and post-yaleozoic taxa appear t o be wholly unrelated. RESUHE: Ouelnues faunes bien pre'servges e t bien datges donnent 1 'impression que chacun des Systkrres de l ' n r d o v i c i e n , d u S i l u r i e n , d u De'vonien e t du Carbonif8re peut avoir des populations Radiolaires c , a r a c t f r i s t i q u e s , u? changment, radical dc faune ayant l i e u au, S i l u r i e n Superieur ou, ail Devonien I n f e r i e u r . Les taxa connus d u Paleozoioue e t Ju Postnaleozoioue paraissent compl'etement sans rapport, INTRODUCTION: For re1 i a b l e information on s t r a t i g r a p h i c d i s t r i b u t i o n of Radiolaria i n Paleozoic rocks we depend o n a few wellpreserved, well-dated faunas. Nevertheless, understanding of Paleozoic evolution i n the Subclass has undergone a n a j o r revolution in the l a s t 2 5 years. The new information cannot e a s i l y be summarized. Some important gerera a n d even f a m i l i e s remain unnamed a n d the majority of important assemblaqes a r e b u t p a r t l y described or wholly undescribcd. Vhat follows i s an extended a b s t r a c t of r e l a t i v e l y recent work, much o f i t unoublished. Space allows only inadequate i - l l u s t r a t i o n and p r i o r i t y i s given to important, h i t h e r t o unfigured f o r n s . SYSTCPATIC FRAFEWORK: The systematic framework adopted in t h i s account, outlined below, d i f f e r s in imoortant resnects from those of previous authors, b u t space precludes f u l l discussion. Subclass RADIOLARIA F?iller Order POLYCYSTINA Ehrenberg (emended Riedel) Suhorder SPUEIELL4RIA Ehrenberg I . "PALAEOACTII..IO?IIlIDS" new informal groupin?. All the Paleozoic Spumellaria with s i n g l e l a t t i c e d shell o r two o r more concentric s h e l l s , sometimes oylomate, lackinq t h e i n t e r n a l sniciilar system of Entactiniacea a n d the c h a r a c t e r i s t i c l a t t i c e struct,ure of Rotasphaerids (below). A l a r g e , diverse group, previously included i n the Actir?omriidae tiaeckel (emended Riedel 1967). T h o u g h Palacoactinomids show c l e a r morohol np i c sinii 1 ar i t i es t o pos t - P a 1 eczoic fic t i nomrii d a e , known Pa 1 eozoi c fauras seem t o show a marked decline i r Palaeoactinomids by Late Paleozoic, and i t i s n o t comnletely c l e a r t h a t they a r e , in f a c t , present in Late Paleozoic rocks. S t r a t i g r a n h i c d i s t r i b u t i o n s u g c e s t s , t h e r e f o r e , t h a t Palaeoactinommids a n d Actinomnidae could be Dhylo?enetically s e n a r a t e . 11. "ROTASPHAEnIDS" new i n f o r m 1 grouninq. Paleozoic Spumellaria with s i n g l e , s p h e r i c a l , l a t t i c e d s h e l l with annular meshes, lackinq the i n t e r n a l s p i c u l a r system of t h e Fntactiniacea and disolayino a point o r points upon t h e s h e l l fror: which r a d i a t e 5 or n'ore strong. s t r a i g h t l a t t i c e b a r $ . 1 . F ' n o t e : S u g g e s t i o n s o f h o l l o w s p i n e s a m o n g s t some O r d o v i c i a n Palaeoactinommids tend t o r e i n f o r c e t h i s view, b u t t h e "grouping" i s a l m o s t c e r t a i n l y p o l y p h y l e t i c and s t r a t i g r a p h i c r a n g e s and p h y l e t i c r e l a t i o n s h i p s a r e very unclear a t p r e s e n t .

168

Superfami l y ENTACTINIACEA P,iedel (Family E n t a c t i n i i d a e Riedel 1967) P a l e o z o i c q a d i o l a r i a , c o n v e n t i o n a l l y - thouclh Derhans i n c o r r e c t l y a l l o c a t e d t o S p u m e l l a r i a , w i t h a s p i c u l e of f o u r o r more r a y s , o o i n t - o r b a r - c e n t r e d , c o n s t i t u t i n g t h e main part of t h e s k e l e t o n o r i n c o r p o r a t e d w i t h i n a l a t t i c e d o r spongy s h e l l , e s s e n t i a l l y s n h e r i c a l , w i t h or w i t h o u t pylome. S h e l l very r a r e l y t u b u l a r , pylomate, and r a r e l y (and d o u b t f u l l y ) c o n i c a l , aylomate. 111, Family ENTPCTIIIIIDAE P i e d e l 1967 (enended h e r e i n ) . Entactiniacea with u n l a t t i c e d s k e l e t o n s , t h e s p i c u l e rays not d i f f e r e n t i a t e d t o d e f i n e a o i c a l and b a s a l hemisoheres. h b r e commonly, s k e l e t o n s l a t t i c e d , e s s e n t i a l l y s p h e r i c z l , l a c k i n g nylome. Tyne Genus: Entactinia Foreran. The E n t a c t i n i i d a e a s d e f i n e d h e r e i n c l u d e s t h e whole l a r a e groun of n r e v i o u s l y r e c o g n i z e d "non-Dylomate E n t a c t i n i i d a e " ( c f . Holdsworth 1 9 7 3 ) . C o n s t i t u e n t genera a r e i n t e r p r e t e d i n t h e s e n s e s o f Foreman (1963) a n d F o r t e y and Holdsworth ( 1 9 7 2 ) . IV. Family PYLENTDMEblIDAE D e f l a n d r e 1963 (emended h e r e i n ) . E n t a c t j n i a c e a with s i n g l e e s s e n t i a l l y s p h e r i c a l , l a t t i c e d ( e x t r e m e l y r a r e l y soongy) s h e l l , r a r e l y n o r e than one s h e l l , t h e o u t e r m o s t s h e l l d i s n l a y i n o an a c t u a l o r i n c i n i e n t nylome w i t h d i f f e r e n t i a t e d r i m . Lackinq t u b u l a r or c o n i c a l e x t e n s i o n a s s o c i a t e d w i t h pylome. Tyne Genus: Pylentonema D e f l a n d r e . ? Superfami l y E1:TPCTIPIIACEA \ I . Family PALAEOSCE>!IDIICAE P i e d e l 1967 (emended h e r e i n ) . P a l e o z o i c s p i c u l a r , s i l i c e o u s s k e l e t o n s comprising 6 t o 8 d i v e r g e n t r a y s , a r i s i n g most c o m o n l y from t h e ends o f a very s h o r t median b a r . 3 t o 4 or more e l a b o r a t e l y ornamented d e f i n e a " b a s a l 4 weaker, u s u a l l y unornamented r a y s d e f i n e a n " a p i c a l hemisphere". Type Genus: Palaeoscenidium D e f l a n d r e . VI. Family POPOFSKYCLLIDPE D e f l a n d r e 1964 L a t t i c e s h e l l p e r f o r a t e , t u b u l a r o r conicP1, w i t h open a n e r t u r e . S p i c u l e s c o n f i n e d t o a d a p e r t u r a l i n t e r i o r of s h e l l , b u t !with n o r t i o n s o f some r a y s i n c o r p o r a t e d i n s h e l l w a l l , Type Genus: Popofskyellum n e f l a n d r e . Of t h e t h r e e c o n s t i t u e n t g e n e r a , C y r t e q t a c t i n i a Foreman - nob c o n s t r u e d a s a n o n o s D e c i f i c Genus r e n r e s e p t e d by C y r t e n t a c t i n i a n r j n o t i c a Foreman - i s an u n q u e s t i o n a b l e e n t a c t i n i a c e i d . The i n c l u s i o n of Popofskyellum and T u s c a r i t e l l u m D e f l a n d r e w i t h i n t h e E n t a c t i n i a c e a i s l e s s c e r t a i n , and amongst s p e c i e s of t h e s e g e n e r a , one s p e c i e s of Fnnofskyellum o n l y i s d e f i n i t e l y known t o p o s s e s s i n t e r q a l s p i c u l e s . Subord,er ALBAILLELLARIA D e f l a n d r e 1953 (emended Holdsworth 1 9 6 o a ) . B i l a t e r a l l y synr;ett-icai P a l e o z o i c R a d i o l a r i a with c l o s e d o r ooen frames i r ? which can be d e t e c t e d a fundamental n a t t p r n o f t h r e e r o d s a r r a n g e d ii: t r i a n g u l a r form. V I I . Family CERATnIKTSCIME Pcldsworth 196oa A l b a i l l e l l a r i a i n which t h e s k e l e t a l frame i s c l o s e d a n d t y n i c a l l y c o n s i s t s o f 3 r o d s , a - r o d , b-rod a n d i n t e r s e c t o r , t h e a - r o d comrionly b e a r i n g p a i r e d s p i n e s ( c a v e a l r i b s ) developed i n a n l a w r.or?al t o t h a t o f t h e framc. I d e a l frame with b n t h ends o f a l l q r i w i n a l rric!s n r e x t r a t r i a n p u l a r e x t e n s i o n s , b u t some e x t e n s i o n s nay be s E r p r c s s Genus: C e r a t o i kisclrm D e f l a n d r e . VIII. Family ALEP~ILLELLIC~~E D e f l a n d r e 1952 ( m . h e r e i n ) . A l b a i l l e l l a r i a w i t h a - r o d and i r t e r s e c t o r l o n p e r than b - r o d , i r n a r t developed a s c o l u i - e l l a e w i t h i n l a r o s l y i m o e r f o r a t e s h e l l , n o t i o i n i n o

169

d i s t a l l y o r w i t h j u n c t i o n tenuous ( s e e Holdsworth 1 9 6 9 ) . Tyoe Genus: A1 bai 11 e l 1 a D e f l a n d r e . RADIOLARIA INCERTAE SEDIS I X . RADIOLARIA FAPIILIA NnVA F o r t e y and Holdsvortti 1972 P a l e o z o i c l a t t i c e d o r spongy c o n i c a l s h e l l s , ooen a t b a s e , with s n i r a l l y d i s p o s e d l a t e r a l s p i n e s and a l s o a p i c a l s p i n e s . Lacking i n t e r n a l s n i c u l e . X . Genus C O R Y T H O E C I A Foreman 1963 Paleozoic t u b u l a r , imperforate, s i l i c e o u s s h e l l s . S t r u c t u r e orobably variable and imperfectly know.

X I . SPICULAR FORllS A d i v e r s e , probably p o l y p h y l e t i c , g r o u p of forms with s k e l e t o n s c o n s i s t i n o

of t h r e a d - l i k e s p i c u l e r a y s , n o t o b v i o u s l y r e l a t e d t o any f a m i l y or aenus l i s t e d above. Note: I m o l i c i t i n t h e above t r e a t n e n t i s a r e j e c t i o n a t t b e moment o f arguments f o r D h y l e t i c c o n n e c t i o n s of t h e E n t a c t i n i a c e a with P l a s s e l l a r i a and e x t a n t s p i c u l a t e s o h e r o i d s , such c o n n e c t i o c s a o o e a r i n q d o u b t f u l i n t h e l i g h t o f p r e s e n t l y a v a i l a b l e mornhologic and s t r a t i g r a p h i c d a t a . O f p o s t - P a l e c z o i c f a m i l i e s c o r s i d e r e d by Riedel (1967) t o Clave Pa1eozo:c r e p r e s e n t a t i v e s , P h a c o d i s c i d a e , Spongodiscidae and L < t h e l i d a c a r e omi:ted, a s no c o m p l e t e l y convincing e v i d e n c e of t h e i r e x i s t e n c e has been found in well-preserved Paleozoic faunas. E Q I E F CESCRIPTIOIdS OF T A X A AI:C OUTLINE OF STQATIGWPHIC DIST~TPUTION C A W 3 ? I A Y : 'lo ~-

adeqliate f a u n a s a r e known from t b e A t l a n t i c Borderlands o r

e l s e w h e r e , b u t Palaeoactinommids a r e probably p r e s e n t and "azarov (1975) r e p o r t e d E n t a c t i n i i d a e E( this oaper). ORnnVICIAr::

E x c e l l e n t l a t e A r e n i q i a n R a d i o l a r i a have been d e s c r i b e d f r n r i

t h e ! ' a l h a l l f o n n a Formation, S p i t s b e r g e n ( F o r t e y and Holdsworth 1 9 7 2 ) . P second fauna i s known froiii t h e e a r l y A r e n i g i a n of t h i s Formation ( B r u t o n e t a l . , i n o r e o a r a t i o n ) and a s i r i l a r o c c u r r e n c e i s r e n o r t e d from t h e Table Head Formation, Rewfoundland ( P e r q s t r d m : 9 7 4 ) . P a l a e o a c t i n o m n i d s dominate both S p i t s b e r q e n h o r i z o n s ( " s n h a e r o i d s " of F o r t e y and Holdsworth 1 9 7 2 ) . A r c h i t e c t u r e i s o a r t i c u l a r l y c l e a r i n t h e e a r l i e r assemblage anc e n t a c t i n i a c e i d s o i c u l e s a r e u n a u e s t i o n a b l y a b s e n t . Comonly t h e i n n e r n o s t s t r u c t u r e i s a s u b s p h e r i c 2 1 n i c r o s o h e r e w i t h s t r a i g h t l a t t i c e b a r s , from t h e j u n c t i o n s of which a r i s e t h e orimary s o i t i e s . !n some c a s e s t h i s i s t h e o n l y complete l a t t i c e , b u t more corvonly i t i s e n c l o s e d by a very much l a r g e r s n h e r i c a l she11 with c i r c u l a r p o r e s , l e s s commonly by two such shells. A second broad qroiin l a c k s innermost n i c r o s p h e r e s , h a v i r p 1 t o 3 e s s e q t i a l l y s o h e r i c a l s h e l l s wit;? pores of i r r e g u l a r s i z e a n d s h a p e . s h e l l s b e i n ? sometimes i l l - d e f i r e d

so t b , a t a sub-snonay s t r u c t i i r e r e s u l t s .

Palaeoactinowid snjnes are i n v a r i a b : y d e l i c a t e , unbladed, n e e d l e - l i k e , s o v e t i - e s s l i g h t l y c u r v e d . Conterocrzneous E n t a c t i q i i d a e sbnw varioi,s a r c h i t e c t u r e s , a 1 1

170

r a d i c a l l y d i f f e r e n t from Palaeoactinommids.

Important a r e F n t a c t i n i i d

Genus Hovum Fortey and Holdsworth, w i t h subspherical s h e l l developed from l a t e r a l spinules of 3 of 6 near orthogonal, point-centred s p i c u l e r a y s , and a f f . Entactinia Foreman (Fo&y and Holdsworth) spp. These l a t t e r possess crude, sometimes incomplete s i n g l e l a t t i c e s h e l l s generated e i t h e r by terminal ramification of 4 o f 6 very s t r o n q , bar-centred s p i c u l e r a y s , o r by l a t e r a l s p i r u l e s developed from 1 or more rays of a s i m i l a r s p i c u l e , a l l rays continuing as main spines, frequently terminating with simple b i f u r c a t i o n . Examples of o t h e r a r c h i t e c t u r e s a r e very r a r e a n d include a f f . . Stiamosphaera I RQst Fortey and Holdsworth and E r t a c t i n i i d Genus Flovum 2 . This l a s t i s d i s t i n c t i v e , t h e sub-spherical skeleton developivq from a barc e n t r e @ , 6-ray spicule? b v reneated hifurcations of a l l r a y s , r e s u l t i n q soinules n o t fusing. Entactiniidae a r e a l s o probably represented by 6ray, point- and bar-centred spicules unassociated with any t r u e l a t t i c e . Conical Radiolaria Fainilia iiova sap. a r e confined t o t h e higher Spi tsberqen horizon. Arenigiai Entactiniidae have some s i m i l a r i t i e s t o S i l u r i a n forms ( a s have Palaeoactinommids) b u t d i f f e r completely from Late Paleozoic forms. Potasohaerids, Pylentonemidac, a l l A l b a i l l e l l a r i a a n d nrohably a l l Palaeoscenidiidae a r e apoarpntly absent in the e a r l i e s t Ordovician. Adequate younger Ordovician material i s u n k n o w n from the A t l a n t i c Borderlands, b u t Dunhan a n d fYirDby ( i n w c s s : --. iR 1 i t t . l shot, braninian-like Palaeoactinommids ard Entactiniidae t o p e r s i s t in t h e Caradocian of Nevada, together with W’P tim 7Palaeoactinommids and possibly Fntactinia Foreman S . S . sp. SILUEIfi’:: Well-preserved, h i t h e r t o undescribed padiolaria of Llandoverian throuclh llerllockian aqe a r e known from q r a o t o l i t i c cnncretions of t h e Cape P h i l l i p s Fornation, Cornwallis I s l a r d s . Preliminary study of assemblaqes frorr 1 2 borizons shows Palaeoactinornmids, Rotasphaerids, Palaeoscenidiidae and Ceratoi kiscum s p p . t o be t h e numerically dominant qrouns, with l a t t i c e d Entactiniidae l e s s common than in Late Paleozoic faunas atld with hlcderi-spine forms absent. Ceratoikiscum. spp. a r e undetectPd bP1nvJ the Cyrtocjraptus r i g i d u s Tone (Wenlockian). The r e l a t i v e iniportances of environriental change, s e l e c t i v e d i s s o l c t i o n and evolutionary chanoe i n aetermining the wide v a r i a t i o n in assemblage make-up cannnt y e t k assesscr’. 4mongs t Palaeoactinormids , smal l e r sing1 e atxi double she1 led species appear c l o s e l y comparable with Arenigian forms, b u t far g r e a t e r d i v e r s i t y i s now founa i n the qroiip. bximum l a t t i c e s h e l l diaiwter v a r i e s

171

from 0.15mni. t o 0.85mm. The mnst d i s t i n c t i v e forms a r e t h e l a r f l e r , w i t h outermost s i m p l e , r e t i c u l a t e l a t t i c e w i d e l y s e p a r a t e d from one o r n o r e much s m a l l e r , r e t i c u l a t e i n n e r l a t t i c e s .

I n v e s t i r a t i o n o f innermost

s t r u c t u r e i s more d i f f i c u l t t h a n a t Ordovician h o r i z o n s , b u t i n no i n s t a n c e so f a r where i t has been n o s s i b l e t o d e t e r m i n e t h e innermost d e t a i l s of a S i l u r i a n forni i . : C c . t h a n one snheroirial l a t t s c e h a < ? P V ~ T P - Q

t r a c e been found of an e n t a c t i n i a c e i d s p i c u l e . P r e s e n t l y i t can o n l y be concluded t h a t t h e common, m u l t i s h e l l e d and r a r e r sponcjy S i l u r i a n s p h e r o i d s a r e Palaeoactinoniniids. : j u q b 2 r and s p a c i n g o f l a t t i c e s h e l l s i s v a r i a b l e i n t h e g r o u p , a s i s main and s u b s i d i a r y s p i n e c o u n t , b u t s o i n e s a r e i n v a r i a b l y unbladed r o d s - e x c e p t i n t h e i n s t a n c e o f a r e l a t i v e l y r a r e group w i t h d e l i c a t e , sub-sponl;y s h e l l s which n o s s e s s 4 t o Drobahly 6 s t r o n g , t h r e e - b l a d e d major s n i n e s . These a r e t h e e a r l i e s t exaninles of bladed s p i n e s d e f i n i t e l y known t o t h e w r i t e r i n t h e P a l e o z o i c r e c o r d . The Ro t a s p h a e r i d s a r e t o t a 11y d i s t i n c t from t h e Pa l a e o a c t i noiimids i n p o s s e s s i n g o n l y one s n h e r i c a l l a t t i c e s h e l l which i n v a r i a h l y shows a t l e a s t p a r t of t h e s h e l l i n c o r p o r a t i n g n o t a b l y s t r a i q h t b a r s which r a d i a t e from a c e n t r e , o f t e n a s s o c i a t e d w i t h a s n i n e b a s e . P o s t commonly, oerhans i n v a r i a b l y , more t h a n one r a d i a t i o n o o i n t i s p r e s e n t . I n t e r i o r s a r e c l e a r l y s e e n and t h e r e i s no t r a c e of s t r u c t u r e w i t h i n t h e s i n g l e s h e l l . S p i n e s are never l e s s than 6 , commonly more, i n v a r i a b l y r o d - l i k e h u t i n very r a r e i n s t a n c e s w i t h a v e r y s l i g h t s u a g e s t i o n of i n c i p i e n t b l a d i n g . The commonly r o b u s t s h e l l s a r e l i k e l y t o have been s o l u t i o n - r e s i s t a n t , so t h a t t h e p r e s e n c e of t h i s g r o u p i n t h e C o r n w a l l i s S i l u r i a n a s s e m b l a o e s , b u t a p p a r e n t l y i n no d e f i n i t e l y o l d e r o r d e f i n i t e l y younger f a u n a s , may be of particular biostratigraphic significance. E n t a c t i n i i d a e o c c u r i n r a t h e r i n s i g n i f i c a n t numbers. A s i n g l e s p e c i e s of E n t a c t i n i i d Genus tlovum i s very s c a r c e , d i f f e r i n ? fro11 t h e A r e n i g i a n forms i n having rounder p o r e s and more d e l i c a t e s h e l l . I n m a t e r i a l so f a r examined E n t a c t i n i a S.S. i s p r o b a b l y r e n r e s e n t e d by no more t h a n 4 s m a l l , r a r e s p e c i e s , a : l with unbladed s p i n e s and d e l i c a t e or v e r v d e l i c a t e i n t e r n a l s p i c u l e s , and E n t a c t i n o s p h a e r a S . S . I.as n o t h ? ? n d e f i n i t e l y r e c o g n i z e d . C f . E n t a c t i n i a i s r e p r e s e n t e d by even s m r c r r specimens w i t h v e r y s t r o n g , ti-ray, b a r - c e n t r e d s p i c u l e and h i r h l y e c c e n t r i c , c r u d e and probably incomplete r e t i c u l a t e s h e l l g e n e r a t r r ’ by l a t e r a l s p i n u l e s from s p i c u l e r a y s which c o n t i n u e a s r o d - l i k e s p i n e s . E n t a c t i n i i d a e l a c k i n g t r u e , r e t i c u l a t e s h e l l a r e s l i g h t l y more abundant a s a g r o u p , b u t i n d i v i d u a l s p e c i e s e q u a l l y r a r e . Amongst t h e s e , E n t a c t i n i i d Genus Novum 2 i s c l o s e l y comparable w i t h t h e form from t h e

172

7owest A r e n i q i a n .

9 f o r m w i t h b a r c e n t r e and 7 v e r y strong r a y s shows

s p i r u l e s a r i s i n g l a t e r a l l y a t m o r e t h a n one l e v e l f r o m r a y s , n r e f e r e n t i a l l y developed on 4 r a y s .

V o s t a b u n d a n t i s a g r o u p w i t h 6 r a y s and s h o r t o r

v e r y s h o r t b a r c e n t r e h a v i n q l a t e r a l s p i n u l e s a r i s i n q f r o m one o r m o r e l e v e l s , e q u a l l y d e v e l o p e d o n each r a y A f f . Entactinia

-

H a p l e n t a c t i n i a Foreman s . 1 . SDO.

snn. o f A r e n i g i a n t y D e a n n e a r a b s e n t .

The

S i l u r i a n E n t a c t i n i a spp. and H a p l e n t a c t i n i a - l i k e f o r m s Seem t o * c n r e s e i t "advance' i n development r e l a t i v e t o t h ,

b i t i:

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ap

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i c

t h a t t h e C o r n w a l l i s r e t i c u l a t e F n t a c t i n i i d a e s t i l l a p p e a r t o he s c a r c e r and l e s s d i v e r s e t h a n i n known L a t e P a l e o z o i c P $ 5 p ~ ~ i h l ; r o ? , s r d i t

"1uqC

b~

c o n c l u d e d t h a t t h e m a j o r e n t a c t i n i i d r a d i a t i o n was p o s t - W e n l o c k i a n . P a l a e o s c e n i d i i d a e a r e represented b y coimon Palaeoscenidium s . 1 .

snn.

w i t h 3 o r 4 b a s a l s p i n e s and 2 o r 3 a p i c a l s .

They d i f f e r from

Palaeoscenidium S.S. i n l a c k i n g t h e i m p e r f o r a t e , t e n t - l i k e s h e l l s u r r o u n d i n g t h e p r o x i m a l ends o f t h e b a s a l s , b u t b a s a l s a r e ornamented b y n e r d a n t s p i n u l e s , sometimes a m a l g a m a t i n g t o f o r m a n i r r e g u l a r , p e r f o r a t e "tent".

The e n t a c t i n i i d - l i k e b a r f r o m w h i c h b a s a l s and a p i c a l s a r i s e i s

c l e a r and c a n b e d e t e c t e d i n L a t e P a l e o z o i c P a l a e o s c e n i d i u m S.S. SPD.

This

bar i s a l s o c l e a r i n a f u r t h e r , w i d e l y d i v e r s e group o f s p i c u l a r forms here Such f o r m s d i f f e r f r o m

r e f e r r e d t o as " a f f . P a l a e o s c e n i d i u m s p p . " . H a p l e n t a c t i n i a s.1,

i n t h e markedly d i f f e r e n t i a l develonment o f t h e p r i m a r y

s p i c u l e r a y s , and t h e r e i s a c l e a r a p p r o a c h t o t h e b a s a l / a p i c a l p o l a r i s a t i o n c h a r a c t e r i s t i c o f P a l a e o s c e n i d i u v s . 1 . and

S.S.

S i n q l e and

commonly m u l t i p l e b i f u r c a t i o n t e n d s t o mark t h e s t r o n g e r r a y s : l e s s e r l e n g t h , a b s e n c e o f b i f u r c a t i o n o r weak s i n q l e b i f u r c a t i o n marks t h e l e s s developed, a p i c a l analogues. Palaeoscenidium s.1.

Pendant l a t e r a l s p i n u l e s , r e m i n i s c e n t of

a r e f o u n d o n some r a y s .

It i s temntino

f o r r > s a s i n t e r m e d i a t e s between H a p l e n t a c t i n i a s . 1 . Palaeoscenidium s.1.

(Palaeoscenidiidae)

-

to v i e w such

( F n t a c t i n i i d a e ) and

and hence t h e t e p t a t i v e

assignment o f Palaeoscenidiidae t o t h e Suoerfamily Entactiniacea (see S y s t e m a t i c Framework)

I

C e r a t o i k i s c u m sap. and e x c e s s i v e l y s c a r c e R a d i o l a r i a Genus B Foreman sp. r e p r e s e n t t h e f i r s t known a p p e a r a n c e o f C e r a t o i k i s c i d a e and o f A l b a i l l e l l a r i a outside Asia,

(Nazarov

3. (1975)

d e s c r i b e d t h e new,

p o s s i b l y d o u b t f u l C e r a t o i k i s c u m a c a t a n g u l a t u m from t h e L l a n d e i l o - L o w e r Caradoc o f K a z a k h s t a n . )

Absence o f b o t h g e n e r a i n t h e l o w e r p a r t o f t h e

Cape P h i l l i p s F o r m a t i o n ( L l a n d o v e r i a n l e v e l s ) may w e l l b e d u e t o s o l u t i o n . C e r a t o i k i s c u m spp. show i d e a l , r a t h e r d e l i c a t e f r a m e s w i t h no o r weak p a t a g i u m and s l e n d e r c a v e a l r i b s

-

a f e w commonly d e v e l o p e d f r o m t h e d o r s a l

173 end o f t h e b - r o d

-

ornamented o n l y w i t h m i n u t e s e r r a t i o n s .

A v e r y few

" m u t a n t " specimens show d o u b l i n g o f one o r m o r e e x t r a - t r i a n g u l a r r o d s , o r g r o s s d i s t o r t i o n of t h e u s u a l , e s s e n t i a l l y e q u i l a t e r a l f r a m e .

A l l forms

a r e t o t a l l y d i s t i n c t f r o m known L a t e P a l e o z o i c s p e c i e s . O f r a r e , S p i c u l a r Forms, m o s t s i g n i f i c a n t i s a t y o e w i t h 8 c u r v i n g s p i n e s r a d i a t i n g f r o m t h e end o f a s h o r t " s t e m " , r e g u l a r l y spaced s p i n u l e s .

each s n i n e ornamented w i t h

S i m i l a r b!tt s i m p l e r f o r m s a r e o f t e n a b u n d a n t a t

Upner P a l e o z o i c l e v e l s . Forms n o t p r e s e n t i n C o r n w a l l i s assemblages b u t known i n Eurooean S i l u r i a n f a u n a s a r e a p p a r e n t p y l o m a t e P a l a e o a c t i n o m m i d s o f Germany ( S t d r m e r 1966) and A r c h o c y r t i u m D e f l a n d r e s p n . ( D e f l a n d r e 1 9 7 2 ) , p r o b a b l y W e n l o c k i a n , and f r o m B r g t i g n o l l e s , F r a n c e .

These l a t t e r a r e , i n t h e 1

w r i t e r ' s v i e w , t h e e a r l i e s t c o n v i n c i n g P y l e n t o n e m i d a e known.

LATE SILURIAN, EARLY AND MIDDLE D E V O I I I A I I : Adequate assemblages f r o m t h i s c o n s i d e r a b l e i n t e r v a l a r e unknown t o t h e w r i t e r f r o m t h e A t l a n t i c B o r d e r l a n d s , so t h a t , t o i d e n t i f y t h e t i m e o f m a j o r assemblage change w h i c h , i t a p p e a r s , t o & p l a c e b e t w e e n W e n l o c k i a n an? F r a s n i a n , i t i s n e c e s s a r y t o l o o k e l sewhere.

blast s i g n i f i c a n t i s H i n d e ' s ( 1 8 9 9 ) a c c o u n t o f "Tamworth S e r i e s " f o r m s (New S o u t h Wales) w h i c h , i t w o u l d a p o e a r , m u s t b e from r o c k s of E a r l y - M i d d l e D e v o n i a n a g e . Though i t i s i m p o s s i b l e t o D i n - o o i n t t h e h o r i z o n o f a n y d e s c r i b e d s p e c i e s , t h e e n t i r e assemblage i s c l e a r l y m o r e c l o s e l y r e l a t e d t o w e l l - d a t e d L a t e Devonian faunas than t o C o r n w a l l i s S i l u r i a n assemblages. Nazarov ( 1 9 7 5 ) a l s o i n d i c a t e s t y p i c a l L a t e D e v o n i a n forms e x t e n d i n g i n t o t h e b l i d d l e D e v o n i a n of K a z a k h s t a n . I n b o t h r e g i o n s , e s s e n t i a l l y s p h e r o i d a l f o r m s 131;tb i l 2 , l c . i s n i p e s o r e d o m i n a t e - a s i g n i f i c a n t percentage, a t l e a s t , beins E n t a c t i n i i d a e . Thus A b e r d e e n ' s (194U) "Uevoniarl" t a u n a f r o m t h e S a n t i a g o Vember of t h e C a b a l l o s I.lovacu1 i t e , Texas, a m e a r s anomalous i n a p p a r e n t l y l a c k i n g E n t a c t i n i a c e a c o m p l e t e l y ( R i e d e l and Foreman 1 9 6 1 ) . The age o f t h e R o v a c u l i t e and t h e p o s i t i o n w i t h i n i t o f t h e S a n t i a g o F4emher a r e b o t h q u e s t i o n a b l e ( c f . N i g r i n i and N i t e c k i 1 9 6 8 ) . Lower D e v o n i a n c o n o d o n t s from t h e " u p p e r " p a r t o f t h e N o v a c u l i t e ( G r a v e s 1952 : G l e n i s t e r and K l a p o e r ( i n l i t t . ) ) r a i s e t h e p o s s i b i l i t y t h a t some p a r t o f t h e u n i t m i o h t p o s s i b l y b e e v o n i a n , and t h e g r o s s a s p e c t o f t h e S a n t i a F o assemblage, as d e s c r i b e d , seems t o i n v i t e some c o m p a r i s o n w i t b t h e l e s s d i v e r s e o f C o r n w a l l i s p r e - L u d l o v i a n f a u n a s . S a n t i a q o " H e x a s t y l u s " and "He1 i o s p h a e r a " spp. as r e f i g u r e d b y R i e d e l and Foreman ( 1 9 6 1 ) a p p e a r t o b e p o s s i b l e R o t a s p h a e r i d s and t h e l a r g e r mu1 t i s h e l l e d S a n t i a g o s p h e r o i d s compare w i t h C o r n w a l l i s P a l a e o a c t i n o m m i d s . O f S a n t i a g o f o r m s , o n l y " X i p h o s t y l u s " and " S t y l o s p h a e r a " a r e o b v i o u s l y f o r e i g n t o t h e C o r n w a l l i s S i l u r i a n and c l o s e l y c o m p a r a b l e w i t h Tamworth f o r m s . B u t no r e l i a b l e d a t e e x i s t s f o r t h e f i r s t a p p e a r a n c e o f t h e s e and c l o s e l y s i m i l a r f o r m s w i t h s p h e r o i d a l t o s l i g h t l y e l l i p s o i d a l s h e l l s and o n l y two p r o m i n e n t s p i n e s , and i t i s n u i t e p o s s i b l e t h a t they are o f l a t e S i l u r i a n o r i g i n . The u n q u e s t i o n a b l e c o n t r a s t s between p r o v e n b l e n l o c k i a n and p r o v e n F r a s n i a n assemblages ( s e e b e l o w ) c o u l d h a v e been i n i t i a t e d p r i o r t o t h e 1. F ' n o t e : M i d . O r d o v i c i a n " P y l e n t o n e m a " spp. (Plazarov e t a l . 1975) a p p e a r from t h e i r d e s c r i p t i o n s t o b e p y l o m a t e a e o a c t i n o m m i d s .

174

l l i t i d l e D e v o n i a n and q u i t e p o s s i b l y i n l a t e s t S i l u r i a n t i m e .

LATi CEVO':IA:;:

M o s t c o m p l e t e l y d e s c r i b e d a n d i l l u s t r a t e d o f known P a l e o z o i c

assevblages a r e those

-

3f

ti?. F u r q q Eleriber o f t h e O h i o S h a l e (Foreman l C 6 3 )

F w e n n i a n i n a?.: o , i co.iouhni-. w i : ! e i l c e

(Hass 1947 : G l e n i s t e r and K l a n o e r

(-. i n l i t t . ) ) . E n t a c t i n i i d a e doiiiinate t h e t h r e e assemblages s t u d i e d , r e p r e s e n t e d by t h e genera H a n l e n t a c t i n i a , E n t a c t i n i a , Entactinosnhaera F o r e r i a n , P o l y e n t a c t i n i a and T e t r e n t a c t i n i a Foreman.

O f 44 e s s e n t i a l l y

s p h e r i c a l ? l a t t i c e d species, 3 o n l y riay p o s s i b l y l a c k an e n t a c t i n i i d s p i c u l e a n d be r e f e r a b l e t o t h e P a l a e o z c t i n o r i m i d s . absent.

Contrast w i t h Cornwallis S i l u r i a n

Qotiisnktaeri5s a r e

~ ! s s ? - ~ ! ? ~ E :s s

C1-81.l~

-?rL:d ? i d

f u r t h e r under7ined by t h e prevalence o f E n t a c t i n i i d a e w i t h bladed spines and c o n c e n t r i c l a t t i c e s

-

unknown i n t h e Lower P a l e o z o i c .

P a l a e o s c e n i d i i d a e show a m a r k e d d e c l i n e ,

now r e p r e s e n t e d b y o n l y t w o

soecies, Palaeoscenidium cladophorum D e f l a n d r e and q u a d r i r a m o s s Foreman

-

Palaeoscenidium ?

t h e l a t t e r a p p a r e n t l y a remnant o f t h e S i l u r i a n

a f f . P a l a e o s c e n i d i x stocks.

C e r a t o i k i s c i d a e a r e reprosented by 4 snecies

o f C e r a t o i k i s c u m a n d one R a d i o l a r i a Genus B s p e c i e s , a l l v e r y d i s t i n c t f r o i n S i l u r i a n forms.

The m o s t s i g n i f i c a n t i n n o v a t i o n i n t h i s f a m i l y i s t h e

f i r s t a p p e a r a n c e o f a s h e l l e d genus

f i l b a i l l e l l i d a e a r e absent.

-

H o l o e c i s c u s Foreman

-

but

C y r t e n t a c t i n i a p r i m o t i c a Foreman i s h e r e

considered t h e e a r l i e s t r e p r e s e n t a t i v e o f t h e P o p o f s k y e l l i d a e , and F o r i ~ i a n i e l l a c i b d e l o s p h a e r a (Foreman) i s t h e e a r l i e s t known o f t h e Pylentonemidae a p a r t from A r c h o c y r t i c spp. f i g u r e d by Deflandre (1972) from t h e " S i l u r i a n " o f B r c t i g n o l l e s (see above).

The p r o b l e m a t i c

C o r y t b o e c i a i s f i r s t known f r o m t h e H u r o n llember, accompanied b y s e v e r a l S p i c u l a r Forms. P,n o l d e r , e a r l y F r a s n i a n ( P o l y a n a t h u s a s y m m e t r i c u s Zone) assemblage i n e x c e l l e n t n r e s e r v a t i o n i s known f r o m t h e Canol S h a l e , N o r t h

blest T e r r i t o r i e s ( M a c K e n z i e a n d t i o l d s w o r t h , i n p r e p a r a t i o n ) . Pylentonemidae, P o p o f s k y e l l i d a e and Holoeciscus a r e unrenresented, Haplentactinia excessively scarce.

I n other resnocts +ha assaihlan?

compares c l o s e l y w i t h t h e H u r o n f a u n a s , c e r t a i n e n t a c t i n i i d s p e c i e s beinq i d e n t i c a l , others c l o s e l y r e l a t e d .

P a l a e o a c t i n o r m i d s h a v e n o t been

d e t e c t e d and R o t a s p h a e r i d s and A l b a i l l e l l i d a e a r e a b s e n t . P a l a e o s c e n i d i i d a e a r e r e p r e s e n t e d by P . cladonhorum and

0.a f f .

cladonhorum

C e r a t o i k i s c i d a e a r e r i c h e r t h a n i n t h e Huron assemblages, C e r a t o i k i s c u m snn m o r e d i v e r s e , so t h a t t h e a b s e n c e o f H o l o e c i s c u s s t r o n g l y s u g a e s t s t h a t t h e oenus i s o f p o s t - e a r l y F r a s n i a n o r i g i n .

3 o f t h e 4 Huron Ceratoikiscum spa

a r e c l e a r l y r e l a t e d t o Canol s t o c k s , b u t m i n o r s p e c i f i c d i f f e r e n c e s a r e

175

d e t e c t a b l e and probably of b i o s t r a t i g r a p h i c u t i l i t y . P d i s t i n c t i v e Canol v a r i e t y of C e r a t o i kiscum b u j u g u m Foreman i s r e c o g n i z a b l e i n low F r a s n i a n f a u n a s of Nevada and Western A u s t r a l i a . Caveal r i b vane development i n Ceratoikiscum s p i n o s i a r c u a t u m Foreman s . 1 . Group i s g r e a t e r t h a n a t Huron h o r i z o n s and i n marked c o n t r a s t t o Wenlockian development. Within C e r a t o i k i s c u m p l a n i s t e l l a r e Foreman Group e x i s t s a Canol form c l o s e t o Ceratoikiscum avimexpectans D e f l a n d r e ( T o u r n a i s i a n ) , t h e Canol form being unseen a t Huron l e v e l s b u t d e t e c t a b l e i n t h e low F r a s n i a n o f Idestern A u s t r a l i a . C e r t a i n C e r a t o i k i s c u m s t o c k s , a t l e a s t , a p p e a r t o have had a world-wide d i s t r i b u t i o n a t L a t e Devonian t r o p i c a l l a t i t u d e s and a r e r e c o g n i z a b l e i n t h e U r a l s (Nazarov 1973, 1 9 7 5 ) . CARBONIFEROUS: The e a r l i e s t a d e q u a t e fauna i s of t h e Montagne Noire, Southern F r a n c e ( e g . D e f l a n d r e 1 9 6 0 ) , p r o b a b l y T o u r n a i s i a n and c l o s e l y comparable w i t h a proven T o u r n a i s i a n T u r k i s h assemblage (Holdsworth 1 9 7 3 ) . Most i m p o r t a n t i s t h e f i r s t a p p e a r a n c e of t h e A l b a i l l e l l i d a e , r e p r e s e n t e d i n F r a n c e by a t l e a s t 3 A l b a i l l e l l a s p p . and 1 s p e c i e s of Lapidopiscum D e f l a n d r e . Holoeciscus i s now a b s e n t , b u t 5 and perhaps 6 C e r a t o i k i s c u m s p p . were f i g u r e d by D e f l a n d r e ( 1 9 6 0 ) . One may be i d e n t i c a l w i t h t h e Famennian C . s p i n o s i a r c u a t u m s . s . , b u t both French and Turkish T o u r n a i s i a n forms are m o s t l y c l e a r l y d i s t i n g u i s h a b l e from L a t e Devonian s p e c i e s , though r e l a t e d i n some c a s e s . P a r t i c u l a r l y s i g n i f i c a n t i s t h e a n n e a r a n c e of a T u r k i s h s p e c i e s w i t h t h e i d e a l 6 e x t r a t r i a n g u l a r s o i n e s reduced t o 4

"C.

( ? ) apertum" D e f l a n d r e of F r a n c e ) . (possibly Very s t r i k i n g i n French and T u r k i s h f a u n a s i s t h e abundance and d i v e r s i t y of Pylentonemidae - v a s t l y ( I r e d t e r t h a n i n t h e I h r t h h c i - i c a n

l a t e s t Devonian. Deflandre gave t h e names Pylentonerna, Cerarchocyrtium Cyr t i s p ha e r a c t en i um , Cyr t i s p!?a e r o n em i urn, Pa r a a r c h o c y r t i urn a nd I,r c h o c y r t i E t o encompass t h o v a r i a + : n - h i i t classification renains unsatisfactory. F o r m a n i e l l a S . S . a p p e a r s t o be a b s e n t . P o n o f s k y e l l i d a e a r e r e n r e s e n t e d b,v t h e e a r l i e s t known s p e c i e s of Popofskyellum and T u s c a r i t e l l u m , b u t t h e Famennian C y r t e n t a c t i n i a S . S . i s u n d e t e c t e d . Palaeoscenidium cladoDhorum p e r s i s t s from t h e Famennian, b u t t h e o n l y o t h e r r e p r e s e n t a t i v e of t h e P a l a e o s c e n i d i i d a e i s t h e nevi s p e c i e s Palaeoscenidiuri b i c o r n e D e f l a n d r e . Non-pylonate T o u r n a i s i a n s p h e r o i d s a r e v e r y n o o r l y kiown. A nu-hcr oc s p e c i e s a r e E n t a c t i n i i d a e , b u t i n t e r n a l s t r u c t u r e i s seldom c l e a r i n 1

material presently available.

Visebn R a d i o l a r i a remain very p o o r l y known. Re-examination of G.J. H i n d e ' s l a t e Visgan c h e r t s l i d e s from S.W. EnGland (Hinde and Fox 1895) r e v e a l s h i g h l y d i s s o l v e d , p a r t l y c r u s h e d assemblages i n which t h e 1 . F ' n o t e : T r i s e n o s p b a e r a D e f l a n d r e may be a t r u e Palaeoactinommid.

~

-

176 o n l y f o r m s a b l e t o be r e l i a b l y i d e n t i f i e d a r e a few E n t a c t i n i i d a e . H i n d e ' s " L i t h o c a m p e " and " S t i c h o c a p s a " spp. a r e p r o b a b l y A l b a i l l e l l a spp. o u t l i n e s , a n d " P o r o d i s c u s " s p p . a r e f a i r i y c l e a r l y c r u s h e d and D a r t i a l l y dissolved spheroids,

A l a t e Vise/an ( P 2 b )

i n some c a s e s E n t a c t i n i i d a e .

horizon i n black, goniatite-bearing,

shales o f County L e i t r i m , I r e l a n d ,

c o n t a i n s d i s t i n c t i v e , new R a d i o l a r i a Genus B s p p . a c c o m p a n i e d b y t h e e a r l i e s t known i n f l a t e d , b i - w i n g e d A l b a i l l e l l a s p . o f A l b a i l l e l l a u e n n a t a H o l d s w o r t h Group. A . p e n n a t a G r o u p i s a l s o known f r o m a v e r y l o w Namurian ( E l ) g o n i a t i t e h o r i z o n o f t h e F a y e t t e v i l l e Shale, Arkansas, a s s o c i a t e d w i t h a second s p i n o s e A l b a i l l e l l a s n . and s o h e r o i d s w i t h e x t e r n a l c h a r a c t e r i s t i c s t y o i c a l o f Late Paleozoic

E n t a c t i n i i d a e ( N i g r i n i and N i t e c k i 1968).

The Namurian r e c o r d i s a n t i n u e d b y o f t e n e x q u i s i t e l y p r e s e r v e d R a d i o l a r i a

i n t h e b l a c k s h a l e g o n i a t i t e bands o f S t a f f o r d s h i r e and D e r b y s h i r e , - E2b t h r o u g h e a r l y P2a i n a g e ( t i o l d s w o r t h 1964. 19fi6). 1 7 t h e s e

England

bands, E n t a c t i n i i d a e o f t h e g e n e r a P o l y e n t a c t i n i a predominate.

T e t r e n t a c t i n i a i s oresc:!t,

d i v e r s i t y t h a n i n t h e Famennian. are absent.

E n t a c t i n i a , E n t a c t i n o s p h a e r a and b u t shows l e s s

H a p l e n t a c t i n i a and a l l P a l a e o s c e n i d i i d a e

C o n v i n c i n g e v i d e n c e o f P a l a e o s c t i n o m n i d s has n o t y e t been

f o u n d , and t h e r e i s a s t r i k i n g a b s e n c e o f f o r m s w i t h o n l y t r i o , m a j o r s p i n e s , known i n D e v o n i a n f a u n a s ( s e e above, L a t e S i l u r i a n , E a r l y and i ' i d d l e Devonian). Archocyrtium. and

A. c f .

P y l e n t o n e m i d a e a r e known o n l y b y a s i n a l e s n e c i m e n o f

A l b a i l l e l l i d a e a r e r e p r e s e n t e d m o s t commonly b y A . o e n n a t a

pennata (Holdsworth 1966a), spinose sDecies b e i n g e x c e s s i v e l y

r a r e : Lapidopiscum i s absent.

C e r a t o i k i s c i d a e i n c l u d e R a d i o l a r i a Genus K

s p p . , q u i t e d i s t i n c t from a l l o l d e r forms, and C e r a t o i k i s c u m sop., most commonly o f C e r a t o i k i s c u m b i c a n c e l l a t u m t i o l d s w o r t h a n d C e r a t o i k i s c u m t r i c a n c e l l a t u m H o l d s w o r t h Grouus ( H o l d s w o r t h 1 9 6 9 a ) d i s t i n c t f r o m a l l known Dre-IlamLirian s p e c i e s .

-

again, o u i t e

Popofskyellidae are

r e o r e s e n t e d o n l y by e x t r e m e l y r a r e , s p o r a d i c Ponofskyellum snn., and t h e l a s t known o c c u r r e n c e s o f b o t h P o o o f s k y e l l i d a e and C e r a t o i k i s c i d a e a r e i n

All A l b a i l l e l l a r i a a r e r e s t r i c t e d t o r e l a t i v e l y few o f t h e R a d i o l a r i a n h o r i z o n s , and i t i s a t a f e w h o r i z o n s w h e r e t h e r a r e , Zone r i l a .

P o p o f s k y e l lum and sometimes c f . C o r y t h o e c i a specimens a r e f o u n d .

SDicular

Forms a r e f r e o u e n t a t many l e v e l s anti h a v e L a t e D e v o n i a n a f f i n i t i e s . Y o u n g e s t known o f a d e q u a t e P a l e o z o i c assemhlaoes i s t h a t from Eoasianites-bearing,

sponge-rich c o n c r e t i o n s of t h e I n t a r a r e ' Formation,

l i r u q u a y ( s e e e g . Kling a n d ? e i f 1 9 6 9 ) .

Age i s q u e s t i o n a b l e b u t a p p a r e n t l y

w i t h i n t h e i n t e r v a l i
185

Autunian and C a r n i a n P a l y n o f l o r u l e s C o n t r i b u t i o n t o t h e Chronology and T e c t o n i c H i s t o r y o f t h e Moroccan P r e - A t l a n t i c B o r d e r l a n d H a r o l d L. Cousminer The American Museum of N a t u r a l H i s t o r y New York, New York Warren l l a n s p e i z e r Newark C o l l e g e o f A r t s and S c i e n c e s Rutgers University Newark, New J e r s e y Abstract

A p a l y n o f l o r u l e from t h e Moroccan Meseta n o r t h o f Khenifra c l o s e l y matches f o s s i l p o l l e n a s s e m b l a g e s from t h e European Autunian Series, as d e s c r i b e d by Daubinger (1974) and from t h e P i c t o u Group o f Nova S c o t i a ( B a r s s and H a q u e b a r d , l 9 6 7 ) . The age o f t h e s e a s s e m b l a g e s i s l a t e s t C a r b o n i f e r o u s t o e a r l i e s t Permian. A second p a l y n o f l o r u l e from t h e C e n t r a l High A t l a s s o u t h of Marrakech i s o f mid-Carnian a g e b a s e d upon t h e c o n c u r r e n c e of a g e - d i a g n o s t i c p o l l e n s p e c i e s t h a t have been r e p o r t e d from t h e Swiss and E n g l i s h m i d d l e Keuper, t y p e C a r n i a n o f A u s t r i a , and North American T r i a s s i c b e d s i n V i r g i n i a , North C a r o l i n a , P e n n s y l v a n i a , New J e r s e y , Texas, New Mexico, and A r i z o n a .

These a g e d e t e r m i n a t i o n s serve t o document a l a r g e - s c a l e u n c o n f o r m i t y t h a t encompasses v i r t u a l l y a l l t h e Permo-Triass i c on t h e Moroccan Meseta and High Atlas. T h i s e p i s o d e of pronounced c r u s t a l t h i n n i n g p r e c e d e d T r i a s s i c r i f t i n g , and u l t i m a t e l y l e d t o t h e f r a g m e n t a t i o n o f Pangaea. Introduction Late P a l e o z o i c and E a r l y Mesozoic r e c o n s t r u c t i o n s of

Pangaea a r e i n f e r r e d l a r g e l y on p a l e o m a g n e t i c , g e o p h y s i c a l and l i t h o l o g i c d a t a ( s e e Pitman and Talwani, 1972; P h i l l i p s and F o r s y t h e , 1972; B a l l a r d and Uchupi, 1975; Schenk, 1971; O l s e n and Leydon, 1973; Dewey, Pitman and Ryan, 1973; and many o t h e r s ) .

Paleontologic data bearing

186

on t h i s q u e s t i o n and t h e t i m e of opening of t h e A t l a n t i c , however, are s p a r s e , This paper p r e s e n t s new p a l y n o l o g i c data from t h e Late Carboniferous and Late T r i a s s i c of Morocco t h a t b e a r on t h e sequence of e v e n t s l e a d i n g up t o t h e opening of t h e North A t l a n t i c Ocean. Geologic S e t t i n g Late Carboniferous sediments of Morocco were depo-

s i t e d i n small i s o l a t e d b a s i n s on t h e Moroccan-Oranian

Meseta, and i n l a r g e P a l e o z o i c t r o u g h s of t h e Tindouf and Colomb Bechar Basins (Fig. 1). According t o Michard and Sougy (1974, c i t e d i n Van Houten, 1976), t h e Meseta w a s formed by t h e Late P a l e o z o i c Hercynian (Variscan) Orogeny. The main d e f o r m a t i o n a l phases o c c u r r e d from t h e Namurian t o t h e end of t h e Westphalian, and i n c r e a s e d i n i n t e n s i t y towards t h e margin of t h e A t l a n t i c Ocean. A new e x t e n s i o n a l phase of c r u s t a l deformation oc-

c u r r e d i n t h e E a r l y Mesozoic t h a t fragmented t h e Meseta. Late Triassic c o n t i n e n t a l sediments of Middle Carnian and younger a g e were l a i d down i n grabens i n t h e w e s t e r n High A t l a s as t h e Meseta began t o s e p a r a t e from t h e A f r i c a n

P l a t e (Cousminer and Manspeizer, 1976).

In the Early

J u r a s s i c (Sinemurian), as North America and A f r i c a began t o move a p a r t , t h e Oranian and Moroccan P l a t e s s e p a r a t e d a l o n g t h e l i n e of t h e Middle A t l a s Mountains (Manspeizer, P u f f e r , and Cousminer, 1976b).

E a r l y J u r a s s i c seas, ema-

n a t i n g from t h e Tethys Sea t o t h e n o r t h and e a s t , t r a n s g r e s s e d t h e Meseta a l o n g t h e High Atlas and Middle A t l a s troughs.

/

TINDOUF

RIF

16

,

BASIN

F i g . 1 . Permo-Carboniferous s e d i m e n t s and p r e s e n t - d a y s t r u c t u r a l p r o v i n c e s . 1 = I d a o u Z a l ; 2 = A l m e z i ; 3 = H a d a d j a ; 4 = Ilechra ben Abbou; 5 = Nzala A r r a r c h a ; 6 = S i d i Kassem; 7 = Chougrane; 8 = K h e n i f r a ; 9 = T e l o u e t ; 1 0 = A i t Z i f f a ; 11 = C h i c h a o u a ; 1 2 = Ben A c h o u c h ; 1 3 = T a z z e k a ; 14 = N a s g o u t ; 15 = J e r a d a ; 16 = T r a r a s .

188

Autunian Palynoflorule:

Moroccan Meseta, Khenifra Basin

A diversified palynoflorule was recently recovered from samples collected by John Lorenz in 1974 from a conglomeratic sandstone on the Moroccan Meseta, about 3 . 5 km. north of the city of Khenifra and along the west bank of the Oued O m er Rbia.

The productive samples were col-

lected about 100 meters above the base of a conglomeratic sandstone that is about 5 0 0 meters thick, folded, and unconformably overlying Namurian (Mississippian to Pennsylvanian) metamorphic rocks.

According to Lorenz (1974),

the formation is principal1.y composed of sandstones intercalated with massively bedded conglomerates, containing poorly sorted, well rounded cobbles of vein quartz, quartzite, and metamorphic rock in a sandy and pebbly matrix. Palynomorphs recovered from the samples are listed on Figure 2, and fall into four groups: I.

Lower vascular plant spores: 11. monosaccate

pollen: 111. disaccate pollen: IV. miscellaneous gymnospermous pollen. Because of the occurrence in the Moroccan samples of Pictou Group zonal markers from both the P o t o n i e i s p o r i t e s and V i t t a t i n a zones, a stratigraphic level is indicated equivalent to that near the boundary between these two zones.

This interpretation signifies that the sample is

of uppermost Stephanian to Lower Permian age. Based on this work a direct comparison can be made between the palynoflorules from the type Autunian sediments of Europe and the Khenifra Basin. In Figure 3 are histograms

showing the percentages of spores, monosac-

cates, disaccates, monocolpates and V i t t a t i n a species

*

* *

*

* * *

ENDOSPORITCS LAEVIGATOSPORITES SCHOPFIPOLLENITES APICULATISPnRIS CYCLOGFANISPORITES LOPHOTRILETES PUNCTATISPORITFS Lycnspnm CALAMOS PDRA RETUSOTRILETES CONVOLUTI SPORA LCIOTRILETES KNOXISPORITES X'TICJLATISPORITES LUNDRLADISPORA VESTISPORA

SPORES

MONOSACCATES

POTONIEISP3RITES MONOSACCITES INI1I:T. FLORINITES CORDAIT I N A CY CADOP I T E S MARS UP I P O L L E N I T E S VITTTATINA VESICASPORA L I M I T IS P O R I T ES SULCATISPORITES ILLINITES S T R I OMONOSACC I T E S PROTOHAPLOXY P I N U S STRIATOABIETITES VESTIGISPORITES DISACCITES INDET. HAMIAPOLLENITES STRIATITES FALC I S P O R I T E S

* Fig.

R

ZONAL MARKERS I N P I C T O U GROUP,

MISC

GYMNOSPERMS

DISACCATES

0

1

5 I

1c

I5

I

FR E Q U E N C Y NOV.4 S C O T I A

2 . F r e q u e n c y h i s t o g r a m o f p a l y n o m o r p h s fro'm t h e M o r r o c a n M e s e t a .

20

25

F i ? . 3 . H i s t o g r a m s o f p o l l e n f r o m E u r o p e a n a n d Moroccan A u t u n i a n s e d i m e n t s (European d a t a from Doubinger, 1 9 7 4 ) .

D

c

I. 8

9. 8

m

+

MISCELLANEOUS

HONOSACCATES

MONOCOLPATES

1. 7

2

1 5 DISACCATES

2 . 6 MONOSACCATES

?6. 7 TRILETES

3

2.


o f tn:irinc J u r x s i c sediiiieiits plotteJ oil :I base tiiw ? h o w i n c thc position of the continctits iliiritig thc Hautcrivi;in 11) from Owen 1976 I .

eastwards into Asia. In Middle t o Upper Jurassic times this linked northwards with thc epicontinental sea of north-western America. I t was through these large epicontinental seas that migration of the ostracods t o o k place. The east-west orientated Tethys appears t o have been a somewhet narrow h u t deeper water seaiocean t h a t acted more as a barrier than as a route for migration. This is especially noticeable when comparing the ostracod faunas of the north with those of the southern hemisphere. T h e study of the Jurassic ostracods from the Atlantic Basin indicates that four faunal provinces may be recognised: a European. a Tethyan, a North African and an American. T h e North African Province is perhaps rather tenuouc, a t this stage and may have t o be merged with the Tethyan Province at a later date -.

233 T h c ostracod fauna of thc East African Province is n o t directly relevant t o a stud) of the Atlantic Basin b u t is important in the context of being able t o identify a sotithern as distinct from a northern hemisphere fauna - it is in this way t h a t this province will be briefly involved. Althoiigh a t the present time the greatest diversity of faunas is gcnerally in the tropics and declines away from the equator this does not appear t o have been the case in the Jurassic where a more uniform climate existed. Circumstances a t the onset of the Mesozoic. folloLving o n after thc extinction of most of the Palaeozoic ostracods. were unique in that ecological conditions i i i certain parts of the world were ideal for speciation and subsequent ostracod evolution. Such conditions existed in Europe from the close of Lower Jurassic times onwards. T h u s by the cnd of the Lower Jurassic four important families were alrcad), established : thc Schuleridcidae. the Progonocythcridae. the Protocytheridac and the Cytheruridae. In the Middle Jurassic the ?-rachyleberididae and the Limnocytheridae appear while in thc Upper Jurassic the Ilyocypritlidae dominate the continental deposits. At the present time a zonation of the Jurassic is n o t available although some authors have initiated a zonal scheme for parts of the succession: Anderson ( 1 9 7 1 ) for the Purbeck: Bate (1965) in the Bajocian: Bate & Coleman ( 1 9 7 5 ) in the Toarcian and Michelsen (1975) f o r the Lower Jurassic. A zonal scheme for the British Jurassic is currently i n preparation by Bate. Kilenyi and Lord (see Bate & Robinton).

FAUNAL PROVINCES

The European Province. T h e lateral extent of this province r a n p from Nova Scotia in the west to the Ukraine in t h e east. Northwards the e x t e n t is n o t known as t h e Greenland faunas have n o t been described. southwards the epicontinental sea of the province merges with the deeper waters of the Tethys. . T h e provincial boundaries do n o t remain static through the entire period and it will be some time before precise boundaries can be drawn. Spain. for example. is considered t o have been a part of the European Province during the Lower Jurassic b u t with its anit-clockwise rotation through the Jurassic possibly moved into the Tethy an Province towards the close of the period. T h e maximum diversity of ostracod genera and species exists only a t the centre of the province extending through northern France. England, Germany and Poland. This region appears t o have heen covered by warm, shallow seas in which numerous islands cxisted. Thus not only are marine ostracods numerically a b u n d a n t b u t brackish water lagoonal and estuarine conditions existed f o r further speciation t o take place. FolIowing the extinction of most of the Palaeozoic lineages and a period when continental conditions prcdominatcd in the Trias, the marine transgression during the Jurassic entered a region here that was ideally suited t o ostracod colonisation and subsequent speciation. Because of this rapid evolution in the ostracods t h e European Province appears t o have been the birth-place of the majority of the important Mesozoic families. Indeed some families which evolved then are important a t the present time [c.g. Cytheruridae and Limnocytheridae] . Lower Jurassic - Hettangian t o Toarcian. Although sediments of Lower Jurassic age have been found off Newfoundland and Nova Scotia the ostracods have n o t y e t been described. I t does n o t appear t o b e unreasonable, however, t o tie this region in with the European Province particularly as Ascoli has noticed a relationship between the faunas for Middle and Upper Jurassic (per?. comm.).

234 In general the lower stages of the Lias are not as rich in ostracod species as is the case from the Sinemurian onwards. Initially the faunas are dominated by ogmoconchids and these have been used by Michelsen ( I 975) as the basis of his zonation of the Danish Lower Jurassic. The genus Kitikrlinellu first appears in the British Trias, evolves rapidly throughout the province and the many stratigraphically short ranging species make it an ideal ostracod for zonation (Bate & Coleman 1975). Indeed the two subgenera, Kinkeliriellu fliinkelinellul and Kinkelinellu (Ekt,vphocj,therel are the most important of the cytheracean ostracods I family Protocytheridae] developing at that time. The genus ~2licroprrci,mutoc~,there is first recorded from the Sincmurian [see Proci,therideu reticiilutu Klingler & Neuweiler 19591 and this is currently considered to be the earliest true record of the Progonocytheridae. This family replaces the Protocytheridae i n importance in the Middle and Upper Jurassic with the decline of the Kinkrlirielh-Ekt~'~Jhocj'there lineage, although the Protocytheridae still retain an important position in ostracod phylogeny and become importznt again with respect t o their use in stratigraphical correlation. Many new genera appear towards the close of the Lower Jurassic [ e.g. A phclocythere, Truchj,q.there, Xunuc,vthere & Proc>,thc.rirra] that are significantly important in correlation during the Toarcian and the Aalenian ~. there is no clear division between the Lower and the Middle Jurassic at this point with respect to the ostracod faunas. Also by this time the family Cytheruridae was well established [ the earliest record being of Cvtheropteron reticulutunz Michelsen (1 975) from the Lower Sinemuriaii] but the fourth important family, the Schulerideidae, was only just developing Prueschiilerideu pseudokinkelinella Bate & Coleman ( 1 975) from the Toarcian, the earliest representative, considered to be very close t o being the ancestor of the family. The Schulerideidae devclopcd too late to be important in the Lower Jurassic but achieved this role in the Middle and Upper Jurassic. Middle Jurassic - Aalenian to Callovian. The Aalenian has a fauna that links it closely with the Toarcian below hut at the same time contains ostracods having affinities with the Bajocian [e.g. Pnrrrmutoc.cthcre] . In particular the genns Prueschi/lerideu becomes important all over Europe where several spccies occur, all characteriscd by a coarsely pitted ornamentation (Malz 1966). Throughout thc other stages of the Middle Jurassic Prueschiilerideu remains important although its species become smooth-shelled [with a few exceptions - P. butei in the Callovian] and, through Eoschtilcridcu [see Bate 1967, p. 4 0 1 , gives rise to the Schirlerideu lineage sometime i n the early Bathonian. The Prue.whulerideu lineage dies out in the Callovian with P. hutci i i i Britain and P. uicciutu in southern France. that is so In the Bajocian the Progonocytheridae add the important genuy Glj~ptoc.i~there valuable for correlation all over the province. Indeed this genus is known to extend as far east as the Ukraine (Permjakova 1970) and, outside the province, as far east as Uzbekistan currently the (Masumov 1973, see ,I.lucrodcritinu usperu). The genus ;Microp~ieiirnutoc~~tliere, oldest of the family also develops rapidly through the Middle Jurassic where, together with Gl,i~proc,rthereit may be used in zonation. In fact a zonal scheme using species of these two genera is currently being prepared for publication (see Bate & Robinson). appears in the Bathonian of England and Poland more or less at The genus Progotroc~j~there about the Same time and once was thought to be restricted t o the Middle Jurassic. The many species subsecluently placed in this genus from the Upper Jurassic have proven t o belong more correctly to other genera, although one species, as yet undescribed, has bcen found in thc Kimmeridgian of Spain. Although giving its name to the family this genus has become

235 relatively unimportant stratigraphically. In the southern hemisphere, however, a very close relative of Progunoc~ytkere,the genus Mujiingudlu, becomes strikingly successful throughout the Middle to Upper Jurassic and through the Cretaceous. The geographical distribution of .Ilujiinguellu and the subgencra,'genera that developed from it is from Australia and Africa t o South America. This is quite a remarkable achievement considering that both genera certain11 arose from a common ancestor and became virtually restricted to their respectivc hemispheres [only one species of Prugo/iuc:i.there P. luec.i.rcz/lu in the Callovian t o Oxfordian of India is known from the south while no species of Muji/nguella are known from thc north]. Within the Progonocytheridae there are two morphological groups -- the first rather qtiadrate/oval in outline and represented by Progonocyfhere and Glj,ptucj,t/iereand the second having a much more elongate carapace as in Lophocj.tlierc and Firhrbergiellu. Both groups are charactcrised by having many short ranging species iniportant in the correlation of the Jurassic throughout this province. The Kirikelinellu Ekfj,p/ioc>.flierelineage; so important in the Lower and basal Middle Jurassic apparently dies out in the Bathonian to be continued in the Callovian by the genus Pseiitiokirtsoniu. Whatley ( 1970) rightly considers Pseirtiuhot,roiiia Weinholz (1967) to be congeneric with Buloit-c~lluWienholz ( I 967) both originally described from the Callovian of East Germany. Thus the rccord of Buloicvllu from thc Oxfordian of Canada (Brooke & Braun 1972) and of Pmdohiirsoniu from the Callovian and Oxfordian of Britain (Whatley 1970) extend7 the geographical range of this important lineage. Interestingly. lineages i n the northern hemisphere continue with many more changes at genus level than is the case i n the southern hemisphere. In this consideration of the faunal provinces the important ostracods have all been marine i n habit, the diversity of the faunas being measured by the fact that i n the Bathonian of England alone there are some 55 genera and over 100 species. Within this Province. however? the variety of ecological niches provides for the development of both brackish and of freshwater ostracods Bi.sirlc,oc.,i,/,ri.sand some of which are peculiar to the Middle Jurassic but some, Tlieriusj,noc.c,iii?i, Rlicumz, are also important i n later parts of the geological column. The gentis Davii.i/rirlu. extending through the Palaeozoic to the Recent is, of course, also represented, With thc exception of the last named, development of these new ostracods appears to have taken place within the European Province with subsequent migration effecting a world-wide distribution. This also appears to apply to Timiriuseviu and Lirnnucj'thcve although stratigraphically they are never as important as the first three. The record from Israel by Gerry & Oertli { 1967) of B i , ~ i i l m ( ~ i ~ p r i ~ from the Trias is probably misleading as the age of the beds concerned is now considered to be Jurassic (Gerry, pers. comm.). Upper Jurassic - Oxfordian to Tithoiiian. Upper Jurassic ostracods of the European Provincc continue the diversity of forms already encountered. The Progonocytheridae continue with Lophocj~tiiercs. 1. in the Oxfordian and with Macrudentiuu in the Kimmeridgian. Culliuc~c~therit/cu is characteristic of the Upper Oxfordian and Kimmeridgian of northern France (Oertli 1957) and of the Kimmeridgian of southern England (Kilenyi 1969) but is not well represented in the Upper Jurassic of Switzerland (Oertli 1959) close t o the Tethynn Province. It is in Switzerland, as well as i n southern France iDonze 1967,), on the margins of the Tethyan Province, that the true European representatives of Proc~i~flierit/c.u are found. Also within the Upper Jurassic the important Cretaceous genus Protuc,vfhere makes its appearance and is re~

~

corded by Oertli (1957) from the Kimmeridgian of the Paris Basin and by Pokorny i1973) from

236 the Tithonian of Czechoslovakia. Some early form ofProtocythere appears t o be present in the Bathonian of England but this still has to be verified. Otherwise the migration route of the genus would be from the east where it has been recorded from Uzbekistan (see Macrodentina aspera in Masumov 1973). Important amongst the late Jurassic marine ostracods is Paranotacythere - species of which are stratigraphically short ranging but geographically widely dispersed throughout the epicontinental sea area of the province (Bassiouni 1974). Large areas of the province became emergent during the final phase of the Jurassic and continental deposits with fresh and brackish-water ostrdcods stretch from Denmark through England and France and northern Germany into northern Spain and Portugal. Indeed such conditions existed over large areas of Asia, North and West Africa and South America during this time. Freshwater ostracods first appear in the Upper Jurassic of Portugal where they have been utilised by Helmdach (1971) to subdivide both the Oxfordian and the Kimmeridgian. It is only in the Upper Kimmeridgian that Cypridea begins to dominate the freshwater faunas both in Portugal and in the offshore Kimmeridgian of southern Ireland. Henceforth Cvprideu becomes established world-wide in the Jurassic - Cretaceous interval. Indeed: the use of ostracods in zonation was first employed in the Purbeck by Forbes as early as 185 1. Subsequently refinements have been made and the zonal importance of this genus in the British sequence owesmuch t o the work of F. W. Anderson. The Tethyan Province. In Lower Jurassic times this province extended as far west as the Canadian coast (Nova Scotia and Newfoundland) but expanded in the Upper Jurassic into the southern Atlantic Basin. The north-south extent of the Province takes in western North Africa and the southern part of Europe. Lower Jurassic - Hettangian t o Toarcian. As the Lower Jurassic marine transgression spread north and west over Europe the ancestral stock of the new cytheracean lineages was introduced. The resultant diversity that ensued developed away from the Tethys which was a deeper water environment characterised in the main by smooth-shelled ostrdcods. In the Lower Jurassic the genera Ogmocoxcha and Ogmoconchdla dominate the Tethyan faunas, especially in the Pliensbachian where highly ornate species of Ogmoconcha occur in southern Germany (Lord & Moorley 1974c and Malz 1975), Sicily (Barbieri 1964a) and in the Djebel Zaghouan section in Tunisia. Material collected from the Schwabische Alb [SW-Germany] exhibits both a preponderance of ogmoconchids and some of the diversification more commonly associated with the European Province; as such this region is considered to have been situated on the boundary between the two at that time. The fauna described by Drexler (1958) from Bavaria. south of the Schwabische Alb, is of a deeper water fauna more typical of the Tethys. Similarly the Hettangian fauna in the A r d k h e [S. France1 described by D o m e (1966) is also of this deeper water province and is characterised by species of Ogmoconchella, Bairdiac,vpri.~?, Cytherclla and Ci,therelloidea. The ogmoconchids appear to have migrated west through the Tethys and t o have moved northwards into the European Province where they survived until the basal Toarcian when possibly they were unable t o compete with the rapidly evolving cytheraceans. A parallel with the ornate tethyan ogmoconchids is the ornate group of hairdiids that were common in the Trias of this province. For example, Ptychobairdiu schaubergeri is found both in the Kleckenmergel of Austria (Kollmann 1963) and in the Pliensbachian of Djebel Zaghouan,

237 Tunisia while Lord & Moorley (1974a & b) record highly ornate bairdiids: B. hahni and B. a.telfingencnsi.s from the Pliensbachian of SW-Germany. Rarely do these bairdiids occur outside the Tethyan Province although fragments of Ptj.chobairdia sp. have been recorded from the Toarcian of England (Bate & Coleman 1975). Barbieri (1964b) describes the only ostracods t o come from the centre of the province and this Sicilian fauna is composed entirely of smooth-shelled ostracods. All the available cvidence indicates, therefore, that the evolution of the cytheracean ostracods was initiated in the warmer epicontinental seas bordering the Tethys. Middle Jurassic - Aalenian to Callovian. A rather poor fauna is recorded by Barbieri ( 1 964b) from the Bajocian of Sicily and by Donze (1962) from the Bathonian - Callovian of southern France where only three species: Schuleridra caidata, Proc.vtheridea martini and Oligoc.vtherei.7 gauthieri are recorded. The French fauna is not particularly representative of deep water conditions and is considered t o be marginal between the European and Tethyan Provinces. If this is so it would indicate that the northern boundary of the Tethys had receded since the Lower Jurassic. Eastwards through Europe the Middle Jurassic faunas described all lie outside the Tethyan Province - this is true as far east as the Dnieper-Don Depression where Permjakova 11969. 1970) describes a fauna containing at least 5 species of Gl.yptoc,i.thcre. Further east in Uzbekistan the faunas described byMasumov (1973) belong to an epicontinental sea province that must have had continuity with the European Province and at the same time lay t o the north of the Tethys. Perhaps the Middle t o Upper Jurassic faunas of the Middle East should more accurately belong t o the Tethyan Province - in which case the North African Province could be dispensed with entirely. This will become more apparent as research on these faunas continues. Upp-r Jurassic - Oxfordiaii to Tithonian. In the Upper Jurassic the Tethys moved into the opening Atlantic Basin and appears t o have taken with it the important ostracod family. the Schulerideidae. The migration route would not be through the deeper water regions b u t through the more shallow waters of the margins. The genus Procj~tlzeritleasensustricto, first described from the Callovian of western North America (Peterson 1954), is know to be present in the Callovian of Tanzania (Bate 1975), the Callovian and Oxfordian of southern France (Donze 1962) and in the Oxfordian of Switzerland (Oertli 1959) - as well as in western North America and Canada. Because of this wide distribution pattern a simple westward migration by way of the Tethys appears to have been extremely unlikely. Two ostracod faunas described by Oertli (1972) from DSDP wells in the Atlantic [site 100 off the Bahamas :uid site 105 off Cape Hatteras] have been compared with the deeper water Tethyan faunas described by Oertli (1967) from Italy and with the Middle to Upper Jurassic ostracods described from SE. France by Donze (1 962). Only Rairdia (Akidobairdiai farinacciae correlates the Upper Jurassic of Italy directly with DSDP site 100 but the faunas are, nevertheless clearly representative of a deeper water Tethyan Province. Similarities between species of Ac,roc,v?hrre figured by Oertli (1972) and by Pokorny (1973) are not conclusive and in any case the Czechoslovakian fauna is considered to belong more correctly with the European Province. The close proximity of DSDP sites 100 & 105 to the American Province is remarkable for the complete contrast between the faunas. This contrast is considered t o be due entirely t o differences in water depth - a clear indication that Schiileridea could not have migrated westwards in the deeper water regions of the Tethys.

238

Ostracoils such ;is Mucrotlc~ritiriuand Gulliuccj thc~ridcu,so typical of Upper Jurassic sediments of tlie European Province are absent from deeper waters of the Tethys where Donze ( 1 962) describes a fauna. from southern France. dominated by either smooth-shelled or alate species. \Vliercus a zonal scheme for the epicontinental sea facies of Europe and North America is possible it will be some time before this will be so for the deeper water Tethys where smootlishelleti ostracody prcdoniinate and where there is a considerable decline in numbers. The North African Province. the area covered by this province is considered to extend over that part of North Africa lying south of Tunisia and taking i n Egypt arid the Middle East. There is no published information available and studies on the ostracod faunas are at a very preliminary stage. As a result it may be necessary to revise the decision taken here to separately identify this province. Lower Jurassic Hettanpian to Toarcian. No Lower Jurassic ostracods have been described as those ohtainecl from Djebel Zaghoudn are considered to belong to the Tethyan Province. Middle to Upper Jurassic Aalenian to Tithonian. This i n t e n d is grouped together simply hccausc the Jurassic matcrial examined has been rather loose13 dated as Callovian/Oxfordian. I n Jordan. ‘4rnic i~tlic,rit/c.uand Afi.ocj~thcriticaand in southern Israel, Afi.vc>~thcrit/eu. are represeiitell amongst an ostracoti fauna typical of a shallow marine environment. Both 4rnic~~thc~riticu and ilfi.oc.i.thc.uii1c.a were originally described from the Callovian of Tanzania (Bate 1975) and have since been observed i n the Jurassic of Kenya aiid Somalia. Thus these two genera extend northwards as far as North Africa but do not appear to cross the barrier of the Tethys. It is bccnusc of this that a decision was taken to separately identify the North African fauna as being ~

~

distinct from either the Tethyan to the north or the East African to thesouth. but havingconnections with both. The East African Province. The Southern hemisphere ostracod faunas during the Jurassic and. indeed for the Mesozoic in general, are qiiite distinct from those of the northern hemisphere. Ccrtninly many ostracod genera are cosmopolitan in their distribution but the essential composition of the faunas is different. Whereas i n the European Province three families, the Progonocytheridae, the Protocytherih e a n d the Schulerideitlac. play an important role in stratigraphical correlation. here only the Progoiiocytheridae assumes any importance the Schulerideiilae and Protocytheridae are reprcsentccl but i n a subsidiary role. In the East African Province the most important penus is .Maiirngat~/luwhich is very closely related t o Progonocj,thcrc of the European Province. The latter plays a very insignificant part i n Jurassic stratigraph) whereas Majungaellu may be used for correlation between East Africa. India, Madagascar and South Africa. Indeed, five zonal species of ,Vlaj/ingaellahave been recognised in the Jurassic (Bate 1975): IM. mund~rla Callovian; .21. o.yfort/iariu Oxfortlian: .M. kirnriieritlgiana - Lower Kimmeridge: .M. pracperfiirutu ~

~~

~

Middle or Upper Kimmeridge (precise age uncertain) and ‘44. perforatu Tithonian. Additionranges u p into the Cretaceous and is known from Africa, South America [see ally :llujiir~guc~/lu .Yoivcj~thcrrRossi tle Garcia 19721 and Australia. Thus the presence of this genus. or of one of the very closely related subgenera, readily identifies a southern hemisphere fauna as distinct from one from the north. The American Province. The buried Upper Jurassic of the Gulf Coast and of the SE-Atlantic coast of the USA together form the American Province which in faunal terms is characterised by

239

the dominance of Schukridea, Paraschuleridea and Hutsonia. This is a unique, shallow water marine fauna that is more easily correlated with the western North American Jurassic than with the faunas figured by Oertli (1972) from the DSDP well sites in the Atlantic. Lower Jurassic - Hettangian to Toarcian. Absent. Middle Jurassic - Aalenian to Callovian. Absent. Upper Jurassic - Oxfordian to Tithonian. The age dating of this sequence is not precisely known and probably not all stages are present. The characteristic feature of this province is the absolute importance of the the Schulerideidae. Of the large number of rapidly evolving genera that appeared in Europe during the Jurassic only the genus Schulcridea in association with Asciocj,there and Parascliirli~rideaappears to have developed here. European genera such as Fuhrbrrgiella and Aeudohutsorzia present i n the Upper Jurassic of western North America must have arrived there via Greenland and one could postt~latc that the southward extension of the Tethys with the opening of the Atlantic was initially a deep water transgression that was unsuited to the migration of the European genera. I n this context a detailed study of the eastern Canada Jurassic faunas should be very interesting as it would appear that thcre was little or no continuity between there and the American Province further south. The absence of Lower and Middle Jurassic marine sediments in the southern North Atlantic is taken t o indicate that marine conditions were totally dependent upon the opening of the Atlantic and the introduction of the Tethys. The marine Upper Jurassic ostracods of Louisiana and Arkansas [Swain 1946, and Swartz & Swain 19461 and from North Carolina [Swain 1952 and Swain & Brown 19721 are considered to represent a rather restricted, shallow water marine environment that has little direct correlation with the marine Provinces of Europe and North Africa. Unfortunately we have n o information concerning the Jurassic ostracods of Mexico but it is possible that some connection west with a Pacific Province might have been in existence during the Upper Jurassic even though the essential marine transgression of the southern North Atlantic came from the North.

CONCLUSIONS The distribution of the Jurassic Ostracoda was examined in the context of a re-positioning of the continents as they were in late Jurassic times. With the Atlantic closed during the Lower Jurassic, marine conditions entering from the east reached only as far west as eastern Canada. The central part of this transgression - the Tethys - has been identified as a deeper water Tethyan Province characterised by a rather restricted fauna of smooth-shelled ostracods. The primary role of the Tethys appears to have been t o act as a north-south barrier to ostracod migration. Possibly this was because the newly evolving ostracods were unable to tolerate the deeper [cooler?] waters of the Tethys. Bordering the Tethyan Province epicontinental seas spread north over previously barren Triassic landmasses and, following on from the extinction of most of the Palaeozoic lineages, a unique situation arose that led t o rapid speciation and subsequent evolution of many new lineages. Although there is some evidence that similar conditions existed eastwards into Asia, the European Province is considered t o have been one of the major sites of ostracod evolution

240 and certainly the most important in terms of the present study. Elements of the European fauna migrated north to reach western North America during the Upper Jurassic and likewise migrated east into Asia. I n the Lower Jurassic of the European Province the important ostracods are the ogmoconcliids and the Kiii/wliti?lIa Ekti.phocj.therc, lineage of the Protocytheridae. The cytherdcean ostracods develop rapidly towards the end of the Lower Jurassic and through the Middle and the Upper Jurassic the stratigraphically important ostracods belong to the Progonocytheridae and to the Schulerideitlae. Fresh to brackish-water ostracods of the Limnocytheridae become important in the continental deposits at the close of the Jurassic where the genus Cypridea achieves a worldwide distribution. The development of many short ranging species of this genus led to its recognition as a zonal fossil h y the English geologist Forbes as early as 185 1. The American Province does not appear to have had an epicontinental sea connection with the European Province and as the Tethys was not an effective migratory route only a very restricted fnuna developed of which the most important is the Schulerideidae. Indeed the common occurence of species of Schiileridca, Pamschirlcridea and of Asciocj,there are a characteristic feature of this province. The North African Province has been little studied to date and is presently recognised as containing elements of the East African fauna associated with the cosmopolitan genus C.vthercllu. It is too early i n the investigation of this province to indicate any positive trends in ostracod dcvclopment. The East African Province is introduced into this study solely to draw attention t o the diffcrcnces that exist between the northern and the southern hemisphere faunas and t o the restricting effect 011 migration of the Tethys. Although inany ostracods such as Cj.thcvellu and Fairtliu have ii cosmopolitan distribution those ostracods that had their origins in the Jurassic were essentially restricted to a migration route within their respective hemisphere. AnzicFtherideu and A froci,thcritiea for example extend north into the North African Province but d o not extend further. The genus .Ilajitrigaelh from East Africa appears to achieve a world-wide distribution in thc southern hemisphere hut is not known in the north. The Tethys did, however, permit some migration Proc,vtheridea present in North America and East Africa appears t o be associated in Europe with the marginal facies of the Tethys and the Lower Jurassic ogmoconchids were certainly brought into the European Province by the Tethys. Finally. three Lower Jurassic genera of the European Province: Proc.vthcrura, Enc.vthc,rirru and C),theropteroii appear much later in the Middle t o Upper Jurassic of East Africa (Bate 1975) indicating that some north-south migration has been possible. ~

241 REFERENCES .ASDERSOU, F. U , 1971. In ANDERSON. F. W. & BAZLEY, R. ,A. B. The Purheck Beds of the W'edld ( E n g l a n d ) . Rirll. Geul. Sirrl'. G , B. no. 3 4 , I 7 4 p p , 23 pls. BARBIERI, F . 1964a. lliiizgurcliu l i r ' b l i ~ an u o v o Ostracode del Domeriano. /.'Arcnru Purnzensc, vol. 35. supl. 1 , p. 3-7. .___.._ 1964h. _ _ . hlicropnleontologia del Lias e Dogper del por2o Ragusa 1 (Sicilia). R ~ Y/to/. . Paiconi., vol. 70, p. 709-830, pli. 5 1-66. r e 8. B.ISSIOUNI. M . E. A . A , 1974. P a r a r i u t u c ~ ~ i h c 11. iOstracodd) a u s dem Zzi!raurn Oherjura bis Unterkreide (Kimmeridgium his Albium) von N'cstcuropa. Gcul. Jb.. vol. 1 7 , p . 3-1 I I , I 3 pls. B.\TE. R. H. 1965. Middle Jurassic Ostracoda from the Grey Limestone Series, Yorkshire. Bill/. Rr. .llus. nut. Hirt. geoi., voi. I I , p. 73.133, pls. 1-21. . - .- 1 9 6 7 . The Bathonian Upper Estuarine Series of Eastern England. Pt. I : Ostracoda. Bull Br. .Mus. t i U I . / f i s t . geul., vol. 1 4 , p . 21-66, 22 PIS. . . _ _ .1975. ___ Ostracods __ trom Callovian to Tithonian sediment\ o f Tdnzania. East ,Africa. Biiii. Br. .Zlu\. noi. /list. pevl., vol. 2 6 , p. 161.223, pls. 1-14. . . _ _ .& _COLEMAN. ___ B. t. 1975. Cpper Lias Ostraciida from Rutland and Huntingdonshire. Bidi. G i d S u r b . G,B. no. 55. p. 1-42, 1 5 pls. _ _ _ - _ _ . . & R O B I N S O NE.(eds.). , A Srratigruphicai I n d e x o f British Osrruc~tdu. See1 House Press (in prepn.). BROOKE, \l. M.& B R 4 U U , W. K. 1972. Biostratigraphy a n t i microfaunan of the Jurassic System of Saskatchewan. D e p t . Miti. Res. Sushatchr~waii Report., 1 6 1 , p. 1-83, 26 pls. DOUZE, P. 1962. Contribution ii ]'etude pal&mtologiique d e I'Oxfcirtlien Supt.rieur d e Trept ( I s h e ) .

___

pls. 9-1 1. ..... ....1966. Ortracodes de I'Hettangien entre ,,\tibends et Privas iArd6che). Tvuv. /.ah. Gc%i/. /,,l'UJl, .\'. s., 110. 13, p. 1 2 l - l 3 9 , p 1 ? , 5 - 7 . DRFXLER, I . 1958. Foraminiferen iind Ostracciden aus dern Liasoc von Siebeldingen/Pfdk. Geol. Jh., vol. 75. p. 475.554. pls. 20-27.

GERRY, E . 8, OERTLI, H. J . 1967. Bisuicoc.vpris ' triarsica n . sp. (Crust., Ostrac.) from Israel. Biiil. C e n t r e R c t h . Puii-S!VPA.. vol. 1 , p. 375-381, 1 pl. HklhlDACH, F. F. 1971. Z u r Gliederung limnischhrackischcr sedimcnte des portirgiesischen Ohcrjura ( o h . Callovien - Kimmeridge) m i t Hilfe y o n Ostrakoden. .V. J b . Geol. Paluoi!:. .Iiir.. vo1. 1 I , p , 645-662. KILENYI, T. 1. 1969. The Ortrac(ido cif the Dorsel Kimmeridge Clay. P i i i u e o ~ i t ~ ~vi d~ .~ 1p2~, ~p ,. 1121 GO, PIS. 23-3 1. KLINGLER, W.& UEUWEILER, F. 1959. Lcitende Ostracodcn airs den1 deutscticn LiasA. G e o L J h . . vol. 76. p. 373-410, 6 pls. KOLLLIAUN, K. 1963. 0rtr:icoden :ius tlcr alpinen l r i a r 2. Weiterc Bairtliid;iz. Jti. (;col., v o l . 106, 1). 121-203, pls. 1-11.

LORD, :A. & XfOORLEY, A . 1 9 7 4 a On Biiirdin iiiiiiiii Lord & \loorley sp. n o v . Stcrrw .Atlri.! Osrrac~idSiiell,r, v o l . 2 . p. 1-4. ____ 1974h. _._. On _Boiriliaaselringenensis _ Lord & M o o r l c y S ~ I n, o v . Stereo .1tius O.rtr(iL,oiI S l i e i l i , vol. 2, p , 5-8. _ _ _1_ 9 7. 4. ~ ._ On _ 0 , ~_ n i o c o n c h aiinihii Lord & 4loorlzy s p . nov. .S'rcrro .4 tlar Osirai,iid Siiellr. vol. 2 , p. 9-16. MALZ. H. 1966. Zur Kenntni.. einigcr 0str;icoricii: W e n der Gattunpcn Kiiihclincllu u n d Priic~ ( I i i i i c r i d e u .Sciick. l L ? t l i , , vol. 4 7 , p , 385-404, 111s. 48-49. MASUh4OV. A . S. 1973. Jiirassic iJstrac;idisof Lrhekistaii. 157 p p , , 14 pls. Tarhkcnt [in Russian], MICHELSEN. 0.1975. Lowcr Jiirassic hiostratigraphy and ostracods of the Danish Embaynient. D~rziriarl~, gcol. iirid?rs., n u 1 0 4 , 287 pp., 4 1 pls. OERTLI, H. J. 1957. Ostracodes tlu Jurassiqtie SupCrieur d u Bdssin clc Paris ( S o n d a g c Vernon I ) . R e v . I i i s t . Frurlc. PCtrole, v o l . 1 2 , p . 6476 9 5 , pls. 1-7. __ _._1959. _ . Malrn-Ostrakodcn aus tleni rchweiierischcn Juragchirgc. .ilfini. Soc. Hriv. S r i . .\ur., vol. 8 3 , p. 1-44, pls. 1-8. . -1972. 22 Jurassic ostracode? of DSDP Lcg I I (nitcs 1 0 0 antl 105) - Preliminary account. p. 645-6. pls. 1-5. I n , HOLLISTER, C. D., FWING. J. I., e t al., Iriiliai R e p o r t s o f t h c D c c p Sea Drilliiiy Projecl, vol. 1 I , O W E S , 11. G . 1976. Continental ilisplaccment and expansion of thc Earth diiring the hlecoznic antl Cenoioic. Phil. Trails. roi'. S ~ J C Scr. .. A, vol. 281, p. 223-291. PFRMJAKOVA, M.N, 1969. New specicc of Ostrac i i d a from the Bajocian Dcpmits o f the Diiieper-Don Depression. Puleorit. Shorilik., no. 6 , p. 34-38, I 111. [ i n Russian]. 1970. OFtracoda of the genus G/,sptocythere from the Midrllc Jurassic Deposit? o f the Dniepcr-Don Depression. Paieont. S b o r n i k . , no. 7 , p . 61-67, 1 pl. lin Russian]. POKORNY, V. 1973. T h e Ostracoda of t h e Klentnice Formation (Tithonian?) Czechoslovakia. A c d . riahiad. Ces. A k u d . ved. YO]. 4 0 , P. 1-107, ?o plS. ROSS1 DE GARCIA, F. 1372. Ostracoda. In: MALMUMIAN, N., MASIUK, V. X ROSS1 D E GARCIA, E. Micrtifbsilcs del CretPcico superior d e 13 pcrforacibn SC-I, provincia ric Santa Cruz, Argentina. Revia. Asoc. @iil. Arcyenr., vol. 2 7 , p . 265-272, I pl. SWAIN, F . M. 1946. Upper Jurassic Octracoila from the Cotton Valley G r o u p in Northern Louisiana: the genus Hutsonia. J . Paleont., YOI. 20, p. 119-129, PIS. 20-21. .___ 1952. __ Ostracoda _ _ _ from wells in North Carolina: Part 2 . Mesozoic Ostracoda. U.S. Geol. Suri'. Prof. Pup., 234-B. p. 59-93. pls. R,9.

__

_____

________

242 REFERENCES SWAIN & BROWN, P. M. 1972. Lower Cretaceous, Jurassic ( ? ) and Triassic Ostracoda f r o m the Atlantic Coastal Region. U. S. Geol. Surv. Prof. Pup, 7 9 5 , p . 1-55, 9 pls. SWARTZ, F. M , & SWAIK, F. M. 1946. Ostracoda f r o m the Upper Jurassic Cotton Valley Group of LouiTiana and Arkansas. J. Puleont., vol. 20, p. 362-373, pls. 5 2 , 53.

WHATLEY, R . C. 1970. Scottish Callovian and Oxfordian Ostracoda. Buii. Br. Mus. n a f . H i s i . geui., vol. 1 9 , p. 297-358, 9 pls. WfENHOLZ, E. 1967. Neue Ostracodcn aus den1 nhic ranges of selected dinoflagellates.

In ascending stratigraphic order,

these ard the CHATANGIELLA VNIGYII zone, CHATANGIELLA MANUMII zone, CHATANGIELLA

NE\J SPECIES

zone, DICONODINIUY FIRh4UM zone, DEFLANDREA OEBISFEL-

DENSIS zone, and the DEFLANDREA BAKER11 z o n e .

One new species, C h a t a n g i e l l a

new s p e c i e s

,

is proposed.

Relative

percentage distribution data reveal an inverse relationship between Palaeoh y s t r i c h o p h o r a i n f u s o r i o i d e s and P . p a u c i s e t o s a .

The possibility is raised

that these species are morphotype variants of one species, dependent on some environmental factor ( s ) .

Ii4TRODUCTION

The purpose of this study is to propose a biostratigraphic zonation for Upper Cretaceous peridinioi?, dinofl3qellate cysts in the Xew Jersey Coastal Plain near Toms River.

The U?per Cretaceous section was recovered

370 from t h e Toms R i v e r Chemical Well N o . 84 (see Figure 1, Location Map). The samples from this s e c t i o n were made available by the U . S .

Geological

Survey.

41 I

11 00

40 I

I 0 00

39 0

19 00

I

15 00

10

0

I0

20

30

14 00

F i r j u r e 1 . S k e t c h map o f New J e r s e y s h o w i n ? a p p r o x i m a t e l ~ o s i t i o no f Toms R i v e r Chemical Well N o . 8 4 .

371 Investigations of Upper Cretaceous dinoflagellate cysts have been undertaken in Australia (Cookson, 1955, 1955; Cookson and Eisenack, 1958, 1960, 1961, 1962, 1968, and 1970), Europe (Alberti, 1959, 1961; Clarke and Verdier, 1967; Davey, 1970; Wilson, 1971), Africa (Davey, 19691, South America (Menendez, 1965), North America (Felix and Burbridge, 1973; Manum and Cookson, 1964; Harland, 1973; McIntyre, 1974; Drugg, 1967) and the USSR (Vozzhennikova, 1967).

These investigations show that many dinoflagellate

species have geographically wide ranging stratigraphic potential. The Toms River section is approximately 2,000 feet in thickness and ranges in age from Late Albian (Doyle, 1973

-

Pollen Zone IIC) to Tertiary.

The part of the section studied is that interval from subsurface depths of 1031 feet to 508 feet and ranges in age from Mid- to Upper Campanian to Tertiary.

The study was restricted to this interval because peridinioid

cysts are most abundant in the Upper Cretaceous and because little biostratigraphic work in this interval has been published.

The Lower and lower

Upper Cretaceous part of the Toms River section was zoned by Doyle (1973) utilizing pollen. Peridinoid dinoflagellate cysts, especially cavate species, were studied because of their abundance, ease of recognition and generally good preservation.

MATERIALS AND METHODS

Twenty samples of sediment, from the stratigraphic interval between 1031 feet and 508 feet depth, cored from the Toms River Chemical Well No. 84, were examined.

LITHOSTRATIGRAPHY

Based on data made available by W.J. Perry of the U.S. Geological Survey, the Tonis River section (TR1031 through TR508) consists of the f o l -

372 lowing lithostratigraphic units in ascending stratigraphic order: Woodbury Formation, Englishtown Formation, Marshalltown Formation, Wenonah Formation, Monmouth Group, Hornerstown Formation and the Vicentown Formation. These units have been identified on the basis of Gamma Ray and Self Potential Curves and lithological descriptions by the U . S .

Geological Survey.

BIOSTRATIGRAPHY

R.K. Olsson (pers. corn.) provided ages based on foraminifera1 data for the Toms River section studied.

The ages assigned are Campanian, Maes-

trichtian, and Tertiary (Figure 3).

The samples above the stratigraphic

level of sample TR599 (e.g., T'R591, T'R577, TR554, TR531, and TR508) are of Tertiary age.

The stratigraphic interval from level 1031 to somewhere be-

tween level 761 and 738 is Campanian.

The interval from somewhere between

levels 761 and 738 to level 599 is Maestrichtian. Dinoflagellate data suggest that the entire studied section (samples TR1031 to TR508) ranges in age from no older than Turonian to Paleocene. The Turonian lower limit is based upon the appearance of Chatangiella vnigrii (Lentin and Williams, 1975) in the lowest sample studied, TR1031. Caution is exercised in setting this age limit because C. vnigrii has been cite? in the literature only once at this writing (Vozzhennikova,1967), from the Turonian of Kazakhstan, USSR.

The geographic and time stratigra-

phl.c range of this species has not been firmly established.

Other species

occurrinq in sample TR1031 are Deflandrea echinoidea (Cookson and Eisenack, 1960), Palaeohystriciiopliora infusorioides (Deflandre, 1934) and P. paucisetosa

(Deflansre, 1943). Wi1liarc.s et a 1 (1974) reported the occurrence of

P. infusorioides in Early to Middle Albian material d t e d with foraminifera

from the Scotian Snelf of eastern Canada.

Deflandrea echinoidea has been

found in material as old as latest Albian (Vraconian) in the western North Atlantic (Sverdlove and Habib, 1974).

Palaeohystrichophora paucisetosa

373 however, has not been reported from material older t h m Coniacian (Sarjeant, 1967). Caution is exercised against assigninq a Coniacian lower age limit for the section because P. paucisetosa has not been frequently cited in the literature, and there is evidence from this study that P. infusorioides and

P. paucisetosa may be morphotype variants dependent upon some environmental factor(s). Doyle's work (1973) on angiosperm pollen types in the Atlantic Coastal Plain, including the lower section of the Toms River core (2000 feet to 1250 feet) places the Cenomanian/Turonian boundary at approximately 1250 feet, the approximate limit of Pollen Zone IV. The f:retaceous/Tertiary

boundary based upon dinoflagellates would be

placed somewhere between the levels of samples TR599 and TR623.

This is

reasonably close to the foraminifera1 boundary between samples TR591 and TR599.

The dinoflagellate species Deflandrea oebisfeldensis (Alberti, 1959)

makes its first appearance in the Upper Eocene of central Europe (Alberti, 1959), Paleocene through Lower Oligocene of the Volga region and the Eocene of the Baltic region (Vozzhennikova,1967).

In addition, the distinctive

outline of its periblast and archeopyle resembles those of other noted Tertiary species such as 2. phosphoritica (Eisenack, 1938) and D . andromedensis (Vozzhennikova, 1967).

Since dating with foraminifera is better established

and more reliable, the probability is greater that the Cretaceous/Tertiary boundary lies between samples TR599 and TR591.

This suggests the extension

of the stratigra.phic range of D. oebisfeldensis to Late Maestrichtian. A Campanian/Maestrichtian boundary is suggested between the levels of samples TR668 and TX646, based upon the stratigraphic disappearance of C h a tangiella manumii (Vozz:?ennikova, 1967) and Palaeohystrichophora infusorioides in sample TRG68, and the first appearance of Deflandrea diebelii (Alberti, 19591, in sample TR646.

C. manurnii has been found in Turonian to

Campanian material in Kazakhstan and Santonian material in western Siberia (Vozzhennikova, 1967).

Palaeohystrichophora infusorioides is found to

range from Early-Middle Albian to Campanian in material dated with foraminifera from the Scotian Shelf (Williams et a l , 19741, and the Grand Banks of New Foundland (Jenkins et a l , 1974). Deflandrea diebelii ranges from Lower Maestrichtian to lower Upper Maestrichtian In material dated with belemnites from Mons Klint, Denmark (Wilson, 1971), and is found in Danian stratotype material from Stevns Klint, Denmark (Wilson, 1971).

Jenkins et a 1

(1974), found D. diebelii to range from Maestrichtian to Paleocene in material dated with foraminifera from the Grand Banks, New Foundland.

Thus, it

appears that sample TR668 can be no younger than Campanian and sample TR646 no older than Maestrichtian.

Stage boundaries cannot be distinguished in

the interval between samples TR668 and TRld31, based on dinoflagellates. Dinoflagellate species found in this interval, which ranges in age from Campanian to no older than Turonian, are Deflandrea echinoidea, Chatangiel-

l a manumii, C. vnigrii, Subtilisphaera pontis-mariae, Chatangiella (new species) , Palaeohystrichophora infusorioides, P. paucisetosa, Chatanqiella victoriensis, and Diconodinium firmum. The published stratigraphic ranges of these species are as follows: Deflandrea echinoidea, latest Albian to Campanian (Davey, 1970; Harland, 1973; Sverdlove and Habib, 1974); Chatangiella manumii, Turonian to Campanian (Vozzhennikova,1967); Subtilisphaera pontis-mariae,Albian (Jenkins et

a l , 1974; Williams et a l , 1974) and Coniacian to Campanian (Sarjeant, 1967); Diconodinium firmum, Upper Campanian (Harland, 1973). Palaeohystrichophora infusorioides and P. paucisetosa The relative percentage distributions of selected peridinoid cysts, other cavate cysts, proximate and chorate cysts, were computed for each sample assemblage studied.

(See Table 2 ) .

The data show an inverse relationship between the re1at;ve percentage distributions of Palaeohystrichophora infusorioides and P. paucisetosa. For example, at the stratigraphic level of 1031 feet, the relative percen-

375

TABLE 2 Relative percenta7c d i s t r i b u t i o n o f ;elected o t h e r c a v a t e , p r o x i m a t e and c h o r a t e cyst;.

peridinioid cysts,

tage of P. infusorioides is 15.49 while for P . paucisetosa it is 24.34.

At

the level of 1009 feet, the relative percentage of P. infusorioides is 4.03 while for P. paucisetosa it is 55.24.

Thus, from level 1031 to level 1009,

the percentage distribution of P. infusorioides decreases while that of P. paucisetosa increases.

At the level of 907 feet, the relative percentage

of P. infusorioides is 56.20 while that of P . paucisetosa 13.57.

From le-

vel 1009 to level 987, P. infusorioides increases while P . paucisetosa decreases in relative percentage distribution.

This observation is made at

each level containing these species except 875, 852 and 761, 738 where the percentage of P . paucisetosa remains fairly constant (less than one percent change). It a,>?ears that when moving from one stratigraphic level to another, an increase in relative percentage distribution of one species is followed by a corresponding decrease in the other. P.

The inverse relationship between

paucisetosa and P. infusorioides apparently shows no corresponding re-

lationship to lit-hologicalchanges.

376 P. infusorioides and P. paucise'msa have similar morphologies.

They

are distinguished on the basis of periblast ornaLnentation, average size, and endoblast.

The periblast of P. paucisetosa has hair-like processes

(setae) which are longer than those of P. infusorioides and more sparsely distributed.

In addition, the periblast of P. paucisetosa, on the average,

is smaller than that of P. infusorioides.

The endoblast of P. paucisetosa

is rarely if ever appressed against the periblast. The question is raised: Are P. infusorioides and P. paucisetosa two separate species which have different specific environmental needs or are they morphotype variants of the same species, i.e., a species population whose average characteristics vary with respect to some environmental factor(s) such as salinity, temperature, trace elements, etc. This is an important consideration because P. infusorioides and P. paucisetosa have different stratigraphic ranges.

If P. infusorioides and

P. paucisetosa are morphotype variants of one species, any zonation utili-

zing the ranges of both species is invalid.

Further investigation into

this issue is warranted and until more information is available, it would be safer to consider the combined stratigraphic ranges of P. infusorioides and P. paucisetosa when making a zonation.

DINOFLAGELLATE ZONATION

Six zones are distinguished from the Upper Cretaceous/Tertiary section at Chemical Well No. 84 near Toms River, New Jersey, based on the stratigraphic ranges of selected peridinioid cysts.

In ascending strati-

graphic order, these are the CHATANGIELLA VNIGRII zone, CHATANGIELLA MANUMI1 zone, CHATANGIELLA

NEW SPECIES

zone, DICONODINIUM FIRYUM zone, DE-

FLANDREA OEBISFELDENSIS zone, and the DEFLANDREA BAKER.11 zone. Of the thirteen species whose ranges are shown in Figure 3, seven are considered to be restricted entirely to the Upper Cretaceous, from their

occurrence in the Toms River (TR) samples and also partially from their distribution in Upper Cretaceous sediments in North America, western Europe, and the Soviet Union.

These are Chatangiella vnigrii, Subtili-

sphaera pontis-mariae, Chatangiella manumii, C. ensis, Diconodinium firmum, and Deflandrea minor.

new species, C. victoriIn addition, one species

is considered to be restricted to the Lower Tertiary.

This species is De-

flandrea bakerii . CIIATANGIELLA VNIGRII ZONE Concurrent range zone defined by the stratigraphic interval from the lowest occurrence of the nominative species up to but not including the lowest occurrence of Chatangiella manumii. Other cavate cysts which appear in the CHATANGIELLA VNIGRII zone include Palaeohystrichophora infusorioides, P. paucisetosa, Deflandrea echinoidea, and Subtilisphaera pontis-mariae.

The most conspicuous feature of

this zone is the absence of C. manumii. The CHANTANGIELLA VNIGRII zone is the lowest zone in the Toms River samples studied.

Its lower limit is not known since samples below 1031

feet were not investigated.

Since its upper limit is approximately 829

feet, the CHATANGIELLA VNIGRII zone is at least 202 feet thick.

The zone

is considered to range in age from upper Lower Campanian to lower Upper Campanian on the basis of foraminifera1 data.

An age range of no older

than Turonian to Campanian is suggested by the published ranges of C. vnigrii and C. manumii. CHATANGIELLA MANUMII ZONE Concurrent range zone defined by the stratigraphic interval from the lowest occurrence of the nominative species up to but not including the lowest occurrence of Chatangiella new species Other cavate cysts which appear in the CHATANGIELLA IMANUMII zone include Palaeohystrichophora infusorioides, P. paucisetosa, and Deflandrea

378 echinoidea. The CHATANGIELLA MANUMII zone ranges in age from lower Upper Campanian to Uppermost Campanian or Lowermost Maestrichtian on the basis of foraminiferal data.

Dinoflagellates suggest an age range of no older than Turonian

to Campanian.

It occurs at the Toms River site from approximately 829 feet

to 738 feet and includes samples TR829, TR806, and TR761.

NEW SPECIES

CHATANGIELLA

ZONE

Concurrent range zone defined by the stratigraphic interval from the lowest occurrence of the nominative species up to but not including the lowest occurrence of Diconodinium firmum. Palaeohystrichophora infusorioides, P. paucisetosa, Deflandrea echinoidea, and Chatanqiella manumii appear stratigraphically within the CHATANGIELLA

NEW SPECIES

zone.

In addition, C. victoriensis and Deflandrea

minor make their first appearance in this zone. The CHATANGIELLA

NEW SPECIES

zone ranges in age from Upper Campa-

nian or Lower Maestrichtian to Maestrichtian on the basis of foraminifera1 data.

Dinoflagellates suggest a Campanian to Maestrichtian age.

It is

found at the Toms River site from approximately 738 feet to 668 feet and is approximately 70 feet thick.

Samples TR738 and TR715 are included in this

zone. DICONODINIUM FIRMUM ZONE Concurrent range zone defined by the stratigraphic interval from the lowest occurrence of the nominative species up to but not including the lowest occurrence of Deflandrea oebisfeldensis. Cavate cysts which appear stratigraphically in the DICCNODINIUM FIRMUM zone include Deflandrea echinoidea, Chatangiella victoriensis, and Deflandrea minor.

D. diebelii makes its first appearance within this zone, a

species whose published range is Maestrichtian to Danian (Alberti, 1959; Wilson, 1971).

The DICONODINIUM FIRMUM zone ranges in age from lower Upper Maestrichtian to upper Upper Maestrichtian on the basis of foraminifera1 data.

Di-

noflagellates suggest an age range of Campanian or Maestrichtian to Maestrichtian or Paleocene.

It is found at the Toms River site from approxi-

mately 668 feet to 599 feet and has a thickness approximating 69 feet. Samples TR668, TR646, and TR623 are included in this zone. DEFLANDREA OEBISFELDENSIS ZONE Concurrent range zone defined by the stratigraphic interval from the lowest occurrence of the nominative species up to but not including the lowest occurrence of Deflandrea bakerii. Deflandrea diebelii disappears stratigraphically within the DEFLANDREA OEBISFELDENSIS zone.

D. bakerii makes its first appearance within this

zone. The DEFLANDREA OEBISFELDENSIS zone has a lower age limit of Upper Maestrichtian to Paleocene based on foraminiferal data.

Dinoflagellate

data disagrees and places the lower age limit in the Paleocene.

The upper

boundary of this zone lies within the Early Tertiary. DEFLANDREA BAKERII ZONE Concurrent range zone defined by the stratigraphic interval from the lowest occurrence of the nominative species.

Because TOTE River samples

above 508 feet were not studied, the upper limit of this zone has not been determined. D. oebisfeldensis occurs in the DEFLANDREA BAKERII zone. The DEFLANDREA BAKERII zone is restricted to the Tertiary in age.

The

upper boundary of the zone is not known.

A COMPARISON OF LITHOSTRATIGRAPHY KITH BIOSTRATIGRAPHY

It is difficult to compare biostratigraphic boundaries with lithostratigraphic boundaries because the lithostratigraphic units are based on the

380 results of a contlnuous gamma log, whereas the biostratigraphic zones are based upon the stratigraphic ranges of dinoflagellates as represented by 20 samples (See Figure 2).

508 531 554 571 599 623 646 668

MONMOUTH GROUP

[,"",.""

,,.,"

FIRMUM ZONE

^..

715 738 761 806 829 852 875

1CHATANCIELLA

1

...__-----

964 987 009 031

WOOOBURV FORMATION

-

VNlGRll ZONE

Figure 2. Chart comparing dinoflagellate zonation with corresponding lithofacies.

Based upon the ages discussed in the beginning of the biostratigraphy section, the Tertiary/Cretaceous boundary lies somewhere at the base of the Hornerstown Formation and the Maestrichtian/Campanian boundary, based on foraminifera1 data, lies somewhere at the base of the Wenonah or top of the Marshalltown.

Dinoflagellate data place this boundary somewhere in the

middle of the Monmouth Group.

The rest of the section ranges in age from

no older than Turonian to Campanian based on selected dinoflagellates and Campanian, based on foraminifera.

ACKNOWLEDGMENTS

T h i s paper w a s made p o s s i b l e through t h e generous g i f t of t h e B. P. Alaska E x p l o r a t i o n Company i n s u p p o r t of R. A u r i s a n o ' s t h e s i s r e s e a r c h and by a g r a n t from t h e N a t i o n a l Science Foundation ( NSF a t Queens C o l l e g e .

-

GA

-

39991 )

im FORAMINIFERA OINOFLAGELLATE

%-

ZONATION

ZONATION

SPECIES LIST

531

55

I

TERTIARY 2

3 4 5 8 1

I J I1 11

I2

I3

FIGURE 3

382 REFERENCES Alberti, G., 1959. Zur Kenntnis der Gattung Deflandrea Eisenack (Dinoflag.) in der Kreide und im Alttertikr Nord--Mitte Deutschiands. Mitt. Geol . Stdatsinst, v. 28, p. 93-105. Clarke, R.F.A. and Verdier, J.P., 1967. An investigation of microplankton assemblages from the chalk of the Isle of Wight, England. vorh. K. Ned. Akad. Net., v. 24, n. 3, 96p. Cookson, I . C . , 1956. Additional microplankton from Australian Late Mesozoic and Tertiary sediments. Austral. J. Mar. Freshw. Res., v. 7, p. 183-191. and Eisenack, A., 1958. Microplankton from Australian and New Guinea upper Mesozoic sediments. ?roc. Roy. SOC. Victoria, v. 70, p . 19-79. , 1960. Microplankton from Australian Cretaceous sediments. Micropaleontology, v. 6, n. 1, p. 1-18. , 1961. Upper Cretaceous microplankton from the Belfast No. 4 Bore, southwestern Victoria. Proc. Roy. SOC. Victoria, V. 74, p. 69-76. , 1962. Additional microplankton from Australian Cretaceous sediments. Micropaleontology, v. 8, n. 4, p. 495-507. , 1968. Microplankton from two samples from Gengin Brook No. 4, Borehole, Western Australia. J. Roy. SOC. W. Austral., v. 51, p. 110-122. , 1970. Cretaceous microplankton from the Eucla Basin, Western Australia. ?roc. Roy. SOC. Victoria, v. 83, p. 137-157. and Manum, s., 1964. On Deflandrea victoriensis n. sp., D.. tripartita Cookson & Eisenack, and related species. ?roc. Roy. SOC. Victoria, v. 77, p. 521-524. Davey, R.J., 1970. Non-calcareous microplankton from the Cenomanian of England, northern France, and North America, part 11. Bull. Br. Mus. Nat. Hist. (Geol.) v. 18, n. 8, pp. 335-397. , 1969. Some dinoflagellate cysts from the Upper Cretaceous of northern Natal, South Africa. Paleontol. Afr., V. 12, pp. 1-23. Deflandre, G., 1934. Sur les microfossiles d'origine planctonique conserve's a ' I'ktat de mati'ere organique dans les silex de la craie. C.R. Acad. Sci. Paris, 199, 966-968. , 1935. Conside/rations biologiques sur les microorganismes d'origine planctonique conserve's dans les silex de la craie. Bull. Biol. Fr. Belg., v. 69, p. 213-244. , 1936. Microfossiles des silex cr&tace/s. Premikre partie. Generalities. Flagellgss; Ann. Pale'ont., v. 25, p. 151-191. , 1940. Microfossiles de quelques silex de la craie blanche de Vendame. Bull. SOC. Hist. Nat. Toulouse, 75, 155-159. _. , 1943. Sur quelques nouveaux Dinoflagellgs des silex crdtace's. Bull. SOC. Ggol. Fr., V. 13, p. 499-509. , 1966. Addendum 'a mon Me'moire: Microfossiles des silex cr6tac6s. Cah. Micropalebntol. (Arch. orig. Cen. Docum. C:N.R.S. no. 419) ser. 1, no. 2, p. 1-9. and Cookson, I.C., 1955. Fossil microplankton from Australian Late Mesozoic and Tertiary sediments. Austral. J. Mar. Freshw. Res., v. 6 , p. 242-313. and Courtville, H., 1939. Note prgliminaire sur les microfossiles des silex crGtac6s du Cambresis. Bull. SOC. Fr. Microsc. 8, 2 ~ 95-106. . et al, 1970. Re-issue of Deflandre and Cookson, 1955 (in French), by Laboratoire de Micropalebntologie de L'Ecole Practique des

383 Hautes Etudes. Institute de Palgontologie du Museum, Palls. avec addendum et post pace, pp. 1-70, 1-54. Douglas, J.G., 1960. Microplankton of the Deflandreidae group in western district sediments. Min. Geol. J., 6(4), pp. 17-32. Downie, C. and Sarjeant, W.A.S., 1966. The morphology, terminologi and classification of dinoflagellate cysts, in Davey, R.J., Downie, C., Sarjeant, W.A.S., and Williams, G.L., Studies on Mesozoic and Cain. ioA, dinoflagellate cysts: Bull. of the British Museum (Nat. Hist.) Geol. supplement 3, p. 10-17. , Evitt, W.R., and Sarjeant, W.A.S., 1963. Dinoflagellates, hystrichospheres and the classification of the Acritarchs.' Stanford Univ. Publ., Geol. Sciences, 7, 1-16. Doyle, J.A., 1973. The monocotyledons: their evolution and comparative biology, Part V. Fossil evidence on early evolution of the monocotyledons. Quart. Review of Biology, v. 48, n. 3, p. 399-413. Drugg, W.S., 1967. Palynology of the Upper Moreno Formation (Late Cretaceous-Paleocene) Escarpado Canyon, California. Palaeontographica, Abt. B, V. 120, p. 1-71. Eisenack, A., 1938. Die Phosphoritknollen der Bernsteinformation als uberlieferer Tertiaren Planktons. Sehr. Phys. b'kon. Ges., v. 70, p.181-188. and Cookson, I.C., 1960. Microplankton from Australian Lower Cretaceous sediments. Proc. Roy. SOC. Victoria, v . 72, p. 1-11. Evitt, W.R., 1961. Observations on the morphology of fossil dinoflagellates. Micropaleontology, v. 7, n. 4 , pp. 385-420. 1967. Dinofilagellate studies 11. The archeopyle. Stanford Univ. Publ., Geol. Sci., v. 10,n. 3, 84p. 1969. Dinoflagellates and other organisms in palynological preparation. Aspects of Palynology, R.H. Tschudy and R.A. Scott (Eds.) Wiley-Interscience, pp. 439-479. 1970. Dinoflagellates. A selective review. Geoscience and Man. v. 1,p. 29-45. and Davidson, S.E., 1964. Dinoflagellate studies I. Dinoflafellate cysts and thecae. Stanford Univ. Publ., Geol. Sci., v. x, n. 1, p. 3-12. and Wall, D., 1968. Dinoflagellate studies IV. 'Theca and cyst of recent freshwater P e r i d i n i u m l i m b a t i u m (Stokes) Lemmermann. Stanford Univ. Publ., Geol. Sci., v. xii, n. 2 , 15p. Felix, C.J. and Burbridge, P.P., 1973. A Maestrichtian age microflora from Arctic Canada. Geoscience and Man, v. vii, p. 1-29. Habib, D., 1972. Dinoflagellate stratigraphy, Leg XI, Deep Sea Drilling Project, in Hollister, C. Ewing, J. Hathaway, J., Paulus, F., Lancelot, Y., Habib, D., Poag, C.W., Luterbacher, H.P., Worstell, P. and Wilcoxon, J.A.. Initial Reports of the Deep Sea Drilling Project, v. X I , Washington ( U . S . Government Printing Office), xxii to 1077p. and Warren, J.S., 1973. Dinoflagellates near the Cretaceous/ Jurassic boundary. Nature, v. 241, n. 5386, p. 217-218. Harland, R., 1973. Dinoflagellate cysts and acritarchs from the Bearpaw Formation (Upper Campanian) of southern Alberta, Canada. Palaeontology, v. 16, part 4 , pp. 665-706. Jenkins, W.A.M. et a l , 1974. Stratigraphy of the Amoco 10E 4-1 puffin B-90 Well, Grand Banks of Newfoundland. Can. Geol. Survey Paper, pp. 74-61. Koch, R. and Olsson, R.K., 1974. Abt. Microfossil biostratigraphy of the uppermost Cretaceous beds of New Jersey. In Abstracts with Programs, v. 5, n. 1, GSA, p. 45. Lejeune - Carpentier, 1942. L'gtude microscopique des silex. Pgridiniens nouveaux ou peu connus. (Dixi'eme note). Ann. SOC. Ggol. Belg. v. 65, p. B181-Bl92. Lentin, J . K . and Williams, G.L., 1975. A monograph of fossil peridinioid

384 dinoflagellate cysts. Bedford Inst. of Oceanography,Rept.Ser.BI-R-75-16. Malloy, 1972. An Upper Cretaceous dinoflagellate cyst lineage from Gabon, West Africa. Geoscience and Man, v. 4, p. 57-65. Manum, S., 1963. Some new species of D e f l a n d r e a and their probable affinity with Peridinium. Arbok Norst Polar Inst. 1962, p. 55-67. and Cookson, I.C., 1964. Cretaceous microplankton in a sample from Graham Island, Arctic, Canada, collected during the second "Fram expedition" (1898-1902). Norske Vid - Akad., Skrifter, I, Mat.-Naturv., 17, 1-36. McIntyre, D.J., 1975. Morphologic Changes in D e f l a n d r e a from a Campanian section, District of Mackenzie, N.W.T., Canada. Geoscience and Man, v. xi, pp. 61-76. Menendez, 1965. Microplancton fosil de sedimentos Terciarios y cretacecos del nort de Tierra del Fuego (Argentina). Ameghiniana, v. 9 , p . 7-15. Minard, J.P. e t a l , 1974. Preliminary report on geology along Atlantic continental margin of northeastern United States. AAPG Bull., v. 58, n. 6, part I1 of 11, p. 1169-1178. Owens, J.P. and Sohl, N.G., 1969. Shelf and deltaic paleoenvironmects in the Cretaceous-Tertiary formations of the New Jersey Coastal Plain. Geology of Selected Areas in New Jersey and Eastern Pennsylvania and Guidebook of Excursions, Rutgers Univ. Press, pp. 235-278. , 1973. Glauconites from New Jersey - Maryland Coastal Plain: Their K-Ar ages and applications in stratigraphic studies. GSA Bull., v. 84, p. 2811-2838. Petters, Sunday, 1976. Upper Cretaceous subsurface stratigraphy of Atlantic Coastal Plain of New Jersey. AAPG Bull., v. 60, n. 1, p. 87-107. Sarjeant, W.A.S., 1967. The stratigraphic distribution of fossil dinoflagellates. Rev. Palaeobotan. Palynol., 1, pp. 323-343. , 1966. Further dinoflagellate cysts from the Speeton Clay: Studies on Mesozoic and Cainozoic dinoflagellate cysts. R.J. Davey e t a l , (eds.), Brit. Mus. (Nat. Hist.) Bull., Geol. Supp. 3, p. 199-214. Snead, X.G., 1969. Microfloral diagnosis of the Cretaceous - Tertiary boundary, central Alberta. Research Council Alberta, Bull. 25, 148p. Stover, L.E., 1973. Paleocene an:?. Eocene species of D e f l a n d r e a (Dinophyceae) in Victorian coastal ar3 offshore basins, Australia. Spec. Publ. Geol. SOC. Aust., 4: pp. 167-188. Sverdlove, M. and Habib, D., 1974. Stratigraphy and suggested phylogeny of D e f l a n d r e a v e s t i t a (Brideaux) comb. nov. and D e f l a n d r e a e c h i n o i d e a Cookson and Eisenack. Geoscience and Man, v. 9, p. 53-62. Upshaw, C.F., 1964. Palynological zonation of the Upper Cretaceous Frontier Formation near Dubois, Wyoming: Palynology in oil\exploration,A. T. Cross (ed.), SEPM Spec. Publ., n. 11, p. 153-168. Valensi, L., 1955. Etude micropalgontologique des silex du Magdalenien de Saint-Amand (Cher). Bull. Soc. Prghist. Fr., 52, p. 584-596. Vozzhennikova, T.F., 1965. Introduction to the study of fossil peridinean algae. Akad. Nauk. SSSR, Sib. Otd., Inst. Geol. Geofiz., ER., 156p. , 1967. Fossil peridinians of the Jurassic, Cretaceous and Paleogene deposits of the USSR. Akad. Nauk. SSSR, Sib. Otd., Inst. Geol. Geofiz., Tr., 347p. Wall, D., 1971. Biological problems concerning fossilizable dinoflagellates. Geoscience and Man, v. 3, p. 1-15. and Dale, B., 1967. The resting cysts of moderi! marine dinoflagellates and their paleontological significance. Rev. Paleobotan. Palynol., 2, pp. 349-354. , 1968. Modern dinoflagellate cysts and evolution of the Peridiniales. Micropaleontology, v. 14, n. 3, p. 265-304. ,1973. Paleosalinity relationships of dinoflagellates

385 on t h e L a t e Q u a t e r n a r y o f t h e Bl.ack Sea - A summary. Geoscience and Man, V . 7 , p . 95-102. Williams, G . L . and L e n t i n , J.K., 1973. F o s s i l d i n o f l a g e l l a t e s : i n d e x t o g e n e r a and s p e c i e s . Geol. S u r . Can., Dept. of Energy, Mines and Res o u r c e s , Paper 73-42, 176p. et al, 1 9 7 4 . S t a t i g r a p h y o f t h e S h e l l Naskapi N . 30 Well, S c o t i a n S h e l f , e a s t e r n Canada. Canadian Geol. Survey Paper 74-50,p.1-12. Wilson, G . J . , 1 9 7 1 . O b s e r v a t i o n s on European L a t e C r e t a c e o u s d i n o f l a g e l l a t e c y s t s . P r o c e e d i n g s o f t h e I1 P l a n k t o n i c C o n f e r e n c e , R o m a 1970. , 1967. Microplankton from t h e Garden Cove Formation, Campbell I s l a n d , N e w Zealand, J . B o t . , v . 5 , p . 223-240.

EXPLANATION OF PLATE 1 1. C h a t a n g i e l l a s p . , approx. 630x. Sample TR668, s l i d e no. RA-1, 7 . 7 ~105.5. V e n t r a l view. Note t h e b r o a d l y a r c h e d e p i t r a c t , two-walled e n d o b l a s t , and d i s t i n c t i v e cingulum. 2 . C h a t a n g i e l l a s p . . Same specimen a s i n f i g . 1 f o c u s i n g on t h e e n d o b l a s t . 3 . C h a t a n g i e l l a s p . . Same specimen a s i n f i g . 1 i n d o r s a l view. Note t h e p a r t i t e cingulum and p r e c i n g u l a r and p o s t c i n g u l a r p l a t e s . 4 . C h a t a n g i e l l a manumii ( Vozzhennikova ) L e n t i n and W i l l i a m s , 1975. Approx. 740x. Sample TR829, s l i d e n o . RA-14, 0 . 7 x 96.3. V e n t r a l view. Note weakly arched e p i t r a c t , cingulum o u t l i n e d by c o n i c a l p r o j e c t i o n s , and c o n i c a l p r o j e c t i o n s s c a t t e r e d about t h e p e r i b l a s t . 5. C h a t a n g i e l l a v i c t o r i e n s i s (Cookson and Manum) L e n t i n and W i l l i a m s , 1975. Approx. 630x. Sample TR623, s l i d e no. RA-15, 3 0 . 5 x 106.8. 6 . C h a t a n g i e l l a v n i g r i i (Vozzhennikova) L e n t i n and W i l l i a m s , 1975. Approx. 630x. Sample TR1031, s l i d e no. RA1 0 , 8.9 x 97.5. V e n t r a l view. Note d i s t i n c t i v e l y arched e p i t r a c t and c o n i c a l a p i c a l h o r n . A l s o , n o t e s u l c u s and c o n i c a l p r o j e c t i o n s on p e r i b l a s t . 7 . D e f l a n d r e a b a k e r i i D e f l a n d r e and Cookson. Approx. 630x. Sample TR554, s l i d e no. RA-9, 0 . 4 x 1 0 3 . 5 . Note s u l c u s and weakly i n d i c a t e d cingulum. Also, note the evenly scabrate ornamentation. 8 . Deflandrea echinoidea Cookson and E i s e n a c k . Approx. 500x. Sample TR1009, s l i d e no. RA-7, 6.4 x 105.3. 9. D e f l a n d r e a minor A l b e r t i . Approx. 630x. Sample TR646, s l i d e no. RA-21, 9 . 3 x 84.2. EXPLANATION OF PLATE 2

1. D e f l a n d r e a o e b i s f e l d e n s i s A l b e r t i . Approx. 400x. Sample TR591, s l i d e no. RA-8, 9.5 x 91.0. Note t h e l a r g e t r a p e z o i d a l a r c h e o p y l e . 2 . Diconodinium firmum H a r l a n d . Approx. 1OOOx. Sample TR668, s l i d e no. RA-6, 1 . 8 x 116.1. mariae Note b i f u r c a t i n g a p i c a l p r o c e s s . 3 . S u b t i l i s p h a e r a p o n t i s ( D e f l a n d r e ) L e n t i n and W i l l i a m s , 1975. Approx. 860x. Sample TR852, s l i d e no. RA-9, 0.4 x 8 7 . 5 . 4 . P a l a e o h y s t r i c h o p h o r a e a u c i s e t o s a D e f l a n d r e . Approx. 1 2 0 0 ~ .Sample TR829, s l i d e no. RA-14, 3 . 1 x 11C.O. 5. 2 p m c i s e t o s a . Approx. 1 2 0 0 ~ .Sample TR1031, s l i d e no. RA-8, 1 1 . 5 x 9 5 . 0 . 6 . P a l a e o h y s t r i chophora i n f u s o r i o i d e s D e f l a n d r e . Approx. 860x. Sample TR806, s l i d e no. RA-1, 6.0 x 8 2 . 1 . V e n t r a l view. Note s u l c u s . 7 . 2. i n f u s o r i o i d e s . Approx. 860x. Same specimen a s i n F i g u r e 1 w i t h f o c u s on e n d o b l a s t . 8. p. infuso r i o i d e s . Approx. 860x. Sane specimen a s i n F i g u r e 1 i n d o r s a l view. Note c o n t i n u o u s cingulum. A l s o , c o n t r a s t r e l a t i v e l e n g t h of s e t a w i t h t h o s e i n F i g u r e s 3 and 4 of p. p a u c i s e t o s a . 9. p. i n f u s o r i o i d e s . Approx. 860x. Same specimen a s i n F i g u r e 1 w i t h f o c u s on e n d o b l a s t i n d o r s a l view.

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NORTH ATLANTIC CENOZOIC FORAMINIFERA by W. A. Berggren Department of Geology and Geophysics, Woods Hole Oceanographic Institution Woods Hole, Massachusetts 02543 and Department of Geological Sciences Brown University, Providence, Rhode Island 02912 Abstract Cenozoic foraminiferal biostratigraphy, biogeography and ecology in the North Atlantic and its marginal borderland areas is reviewed. Planktonic foraminiferal faunal diversity and provincialization exhibit fluctuating patterns which indicate a complex historical relationship between changing paleogeography, paleooceanography and paleoclimatology. Late Neogene climatic deterioration is reflected in increased planktonic foraminiferal provincialization and the development of separate zonations for high and low latitudes as well as a reduction in amphi-Atlantic cosmopolitanism among shallow water benthonic Foraminifera. In a similar manner stratigraphic and geographic distribution patterns among benthonic Foraminifera have been dependent upon the changing geometry of the Atlantic plate. The apparently slow rate of morphologic evolution in most shallow and deep-water benthonic foraminiferal phyletic lineages restricts their usefulness in fine-scaled biostratigraphic studies (the larger foraminifera are an obvious exception), but there has been a renewed interest in using them in paleobiogeographic, paleo-oceanographic and paleobathymetric studies. The evolution of the modern bathyal-abyssal benthonic foraminiferal fauna about 15 Ma allows paleobathymetric and paleocirculation interpretations by analogy with living faunas valid over most, if not all, of the Neogene, and in a general way for the Paleogene as well. RQsumd I1 s'agit de la biostratigraphie c6nozoique foraminifgrale, la bioggographie et l'ecologie dans l'iltlantique du Nord et les cbtes qui l'entourent , La diversite' faunale planctonique foraminifgrale et la provincialisation montrent des motifs fluctuants qui indiquent un rapport historique complique' parmi une pal&oge'ographie, une pal6oocdanographie et une palgoclimatologie changeantes. La dgterioration climatique de la Late Nkogkne est r6fle'chie dans la provincialidation foraminife'rale planctonique augment& et le dgveloppement des zonations sgpare'es des hautes et basses latitudes, ainsi qu'une r6duction dans le cosmopolitanisme amphi-Atlantique parmi les foraminifkres benthoniques des hauts-fonds. D'une faFon semblable, les motifs de distribution stratigraphique et ggographique parmi les foraminifhres benthoniques dgpendent de la g6ometrie changeante de la plate de 1'Atlantique. L'allure Lvidement lente de l'dvolution morphologique dans la plupart des lignages phylktiques foraminiferales benthoniques se trouvant dans les hauts-fonds et les eaux profondes limite leur utilite dans des 4tudes biostratigraphiques sur une petite e'chelle (les foraminifhres qui sont p l u s grands dvidemment font l'exception), mais il y a un renouvellement de l'inte'r8t dans leur utilisation dans des dtudes pale'obiog6ographiques,paldoocdanographiques et paldobathyme'triques. L'gvolution de la faune bathyal-abysaal-benthonique foraminife'rale moderne d'environ 15 Ma permet a des interpr6tation.s paldobathymetriques et palLocirculations par analogie avec des faunes vivantes. C e s interprktations sont valables pour la plupart, sinon toute, le Niog'ene et dans un sens gCngra1, Ie PalLoghe.

1;yTRODUCT I O N

C e n o z o i c p l a n k t o n i c f o r a m i n i f e r a l b i o s t r a t i g r a p h y may b e s a i d t o h a v e matured, i f n o t been b o r n , i n t h e C a r i b b e a n and Gulf C o a s t . >fonographic i n v e s t i g a t i o n s i n t h e 1950's, p r i m a r i l y by o i l company m i c r o p a l e o n t o l o g i s t s , o f t h e P a l e o g e n e a n d Keogene o f t h e C a r i b b e a n - G u l f C o a s t r e g i o n d e m o n s t r a t ed t h e u t i l i t y o f planktonic Foraminifera i n l o c a l and r e g i o n a l s t r a t i graphic s t u d i e s t h e r e and around t h e margins of t h e North A t l a n t i c Basin. The a d v e n t o f t h e Deep Sea D r i l l i n g P r o j e c t i n t h e m i d - 1 9 6 0 ' s p r o v i d e d t h e m a t e r i a l a n d i m p e t u s f o r d e t a i l e d i n v e s t i g a t i o n s on t h e g e o g r a p h i c and s t r a t i g r a p h i c d i s t r i b u t i o n of t a x a a n d t h e f o r m u l a t i o n o f b i o s t r a t i g r a p h i c z o n a t i o n s o f i n c r e a s i n g r e s o l u t i o n . About 40-50 C e n o z o i c p l a n k t o n i c f o r a m i n i f e r a l zones have b e e n r e c o g n i z e d i n t r o p i c a l r e g i o n s . C o r r e l a t i o n o f t h e s e z o n e s w i t h t h e p a l e o m a g n e t i c ( t = 25-0 Y a ) , m a g n e t i c a n o m a l y ( t = 65-0 ?fa) a n d r a d i o m e t r i c ( t = 65-0 Ma) t i m e - s c a l e s i s p r o v i d i n g a g e o c h r o n o l o g i c framework i n which t h e Cenozoic e v o l u t i o n o f t h e A t l a n t i c Ocean c a n b e q u a n t i f i e d . A summary o f r e c e n t a d v a n c e s i n C e a o z o i c p l a n k t o n i c f o r a m i n i f e r a l b i o s t r a t i g r a p h y a n d b i o g e o g r a p h y o f t h e A t l a n t i c Ocean h a s b e e n r e c e n t l y c o r n p l c t e d ( B e r g g r e n , in p r e s s ) , s o t h a t l e s s e m p h a s i s i s d e v o t e d t o t h i s p,:-oup t h a n t h e b e n t h o n i c F o r a m i n i f e r a i n t h i s summary. N o r t h A t l a n t i c Cenozoic p l a n k t o n i c f o r a m i n i f e r a l d a t a are c o n t a i n e d i n t h e P r e l i m i n a r y I i e p o r t s o f t h e Deep Sea D r i l l i n g P r o j e c t ( v o l s . 1-4, 1 0 - 1 5 ) a n d w i l l b e c o n t a i n e d i n t h e f o r t h c o m i n g v o l u m e s 3 7 , 3 8 , 44, a n d 45). S t u d i e s on C e n o z o i c ( e x c l u s i v e o f H o l o c e n e a n d l i v i n g ) d e e p - s e a b e n t h o n i c F o r a m i n i f e r a i n t h e North A t l a n t i c are s t i l l i n t h e i r i n f a n c y . P r i o r t o 1 9 7 0 t h e r e w e r e v i r t u a l l y no p r e - P l e i s t o c e n e d e e p sea c o r e s a v a i l a b l e . Between 1968-1975 t h e Glomar C h a l l e n g e r h a s o b t a i n e d n u m e r o u s c o r e s f r o m s e v e r a l areas o f t h e N o r t h A t l a n t i c ( l e g s 1, 2 , 11, 1 2 , 1 4 , 3 8 , 45 a n d t h e Gulf C o a s t l e g 10) a n d a g e n e r a l p i c t u r e o f t h e d i s t r i b u t i o n OF deep-sea Cerlozoic f a u n a s i s b e g i n n i n g t o e m e r g e . The u s e o f b e n t h o n i c F o r a m i n i f e r a i n b i o s t r a t i g r a p h y h a s b e e n hampe r e d b y l a c k o f c a r e f u l c o m p a r a t i v e taxonomic s t u d i e s which r e p r e s e n t t h e b a s i c d a t a b a s e f o r b i o s t r a t i g r a p h i c and b i o g e o g r a p h i c i n t e r p r e t a t i o n s . The a p p a r e n t l y s l o w r a t e s o f m o r p h o l o g i c e v o l u t i o n i n m o s t s h a l l o w a n d d e e p w a t e r p h v l e t i c l i n e a g e s has r e s t r i c t e d t h e i r usefulness i n fine-scaled b i o s t r a t i g r a p h i c s t u d i e s ( t h e l a r g e r F o r a m i n i f e r a are a n obvious exception), b u t t h e r e h a s b e e n a renewed i n t e r e s t , t r a c e a b l e t o t h e i r i n c r e a s e d r e c o v e r y f r o m t h e d e e p - s e a f l o o r b y t h e Deep S e a D r i l l i n g P r o j e c t , i n u s i n g them i n paleobiogeographic, paleooceanographic and paleobathymetric s t u d i e s . T h i s u s e f u l n e s s w i l l d e p e n d , i n t u r n , upon 1) t h e a b i l i t y t o e x t r a p o l a t e p r e s e n t d i s t r i b u t i o n p a t t e r n s i n t o t h e p a s t a n d 2 ) r e l i a b l e d a t a on (pa1eo)biogeography of benthonic Foraminifera. I t h a s b e e n found t h a t 1) a b o v e i s a p p l i c a b l e o v e r a p p r o x i m a t e l y t h e l a s t 15 my; b e y o n d t h a t i t i s p o s s i o l e t o e x t r i c a t e o n e s e l f f r o m t h e h o r n s o f t h e dilemma b y m a k i n g g e o p h y s i c a l l y - b a s e d s e a - f l o o r t o p o g r a p h i c r e c o n s t r u c t i o n s which t h e n s e r v e as a b a s i s f o r e v a l u a t i n g p a l e o b a t h y m e t r i c d i s t r i b u t i o n p a t t e r n s o f p r e l a t e Neogene t a x a . In t h e c a s e o f 2 ) a b o v e , p r e s e n t l y a v a i l a b l e d a t a s t r o n g l y s u g g e s t t h a t t h e b i o g e o g r a p h i c d i s t r i b u t i o n of b e n t h o n i c foramini f e r a i s s t r o n g l y l i n k e d w i t h p a s t o c e a n - c o n t i n e n t geometry and a t t e n d a n t p a l e o c l i m a t i c and p a l e o c i r c u l a t i o n h i s t o r y (Berggren and H o l l i s t e r , 1 9 7 4 ) . T h i s i s p a r t i c u l a r l y t r u e f o r t h e North A t l a n t i c Ocean and i t s circummarginal a r e a s . The d i s c u s s i o n o f b e n t h o n i c F o r a m i n i f e r a b e l o w r e p r e s e n t s a s y n t h e s i s o f a l a r g e amount o f l i t e r a t u r e i n a d d i t i o n t o c u r r e n t work b e i n g c o n d u c t e d a t o u r own l a b o r a t o r y . Most o f t h e b a s i c l i t e r a t u r e on A t l a n t i c - C a r i b b e a n C e n o z o i c b e n t h o n i c f o r a m i n i f e r a l f a u n a s up t o 1 9 6 9 WDS c i t e d i n B e r g g r e n

391 and P h i l l i p s ( 1 9 7 1 ) . The i n t e r e s t e d r e a d e r i s r e f e r r e d t o t h i s s o u r c e f o r details. Only t h e m o r e p e r t i n e n t r e f e r e n c e s c i t e d t h e r e a s w e l l as t h o s e from t h e i n t e r v a l s i n c e 1 9 7 0 w i l l b e s p e c i f i c a l l y c i t e d h e r e . A d i s c u s s i o n o f t h e t e c t o n i c - s t r a t i g r a p h i c setting o f t h e N o r t h A t l a n t i c ( i n c l u d i n g t h e N o r w e g i a n - G r e e n l a n d S e a ) , a n d t h e m a r g i n a l areas i n N o r t h America a n d E u r o p e p r o v i d e s t h e f r a m e w o r k f o r a summary o f t h e m a i n d i s t r i b u t i o n p a t t e r n s of f o r a m i n i f e r a 1 faunas i n t h e s e t h r e e a r e a s .

TECTONIC-STRATIGRAPHIC SETTING North A t l a n t i c The t e c t o n i c - s t r a t i g r a p h i c e v o l u t i o n o f t h e N o r t h A t l a n t i c Ocean h a s b e e n r e v i e w e d i n terms o f s e a - f l o o r s p r e a d i n g a n d p l a t e t e c t o n i c s by B e r g g r e n a n d P h i l l i p s ( 1 9 7 1 ) , P i t m a n a n d T a l w a n i ( 1 9 7 2 ) , Emery a n d Uchupi ( 1 9 7 2 ) , B e r g g r e n a n d H o l l i s t e r ( 1 9 7 4 ) , L a u g h t o n ( 1 9 7 5 ) , a n d i n Woodland ( e d . , 1 9 7 5 ) , among o t h e r s . The m a i n e v e n t s i n t h e C e n o z o i c e v o l u t i o n o f t h e N o r t h A t l a n t i c may b e e n u m e r a t e d a s f o l l o w s :

1)

I n t h e P a l e o c e n e a c h a n g e f r o m a two t o t h r e e p l a t e g e o m e t r y r e s u l t e d from a s h i f t i n a c t i v e s p r e a d i n g from t h e L a b r a d o r Sea (which c o n t i n u e d o p e n i n g u n t i l t h e Middle Eocene) t o t h e R e y k j a n e s Ridge which r e s u l t e d i n t h e s e p a r a t i o n of G r e e n l a n d a n d E u r a s i a a n d t h e o p e n i n g o f t h e N o r w e g i a n S e a . A t t h i s t i m e R o c k a l l Bank (DSDP S i t e 1 1 6 , 1 1 7 ) b e g a n s u b s i d i n g t o i t s p r e s e n t d e p t h (1200 m). C o n c o m i t a n t l y , b u t c a u s a l l y u n r e l a t e d , O r p h a n Knoll (DSDF S i t e 111) s u b s i d e d t o i t s p r e s e n t d e p t h ( 1 8 0 0 m) d u r i n g t h e l a t e s t C r e t a c e o u s - P a l e o c e n e t i m e . T h e Mesozoic t a p h r o g e n i c s t a g e of r i f t i n g o f t h e North Sea changed t o a n i n t r a c r a t o n i c d r i f t i n g s t a g e i n t h e E a r l y Cenozoic (mid-Paleocene). D u r i n g t h e l a s t 6 0 m . y . t h e N o r t h Sea B a s i n h a s b e e n c h a r a c t e r i z e d by r e g i o n a l s u b s i d e n c e a n d t h e f o r m a t i o n o f a n i n t r a c r a t o n i c b a s i n i n w h i c h t e r r i g e n o u s s e d i m e n t s up t o 3 . 5 km i n t h i c k n e s s h a v e b e e n deposited.

2)

I n t h e Middle Eocene s p r e a d i n g i n t h e L a b r a d o r S e a c e a s e d and G r e e n l a n d became p a r t of t h e N o r t h American p l a t e . The P y r e n e a n o r o g e n y r e s u l t e d i n t h e u p l i f t o f a c e n t r a l r i d g e i n t h e f l o o r o f t h e Bay o f B i s c a y (DSDP S i t e s 118 a n d 1 1 9 ) .

3)

During t h e E a r l y t o Middle Miocene I c e l a n d a p p e a r s t o have formed a s a s u b a e r i a l f e a t u r e , p e r h a p s r e l a t e d t o a m a n t l e plume. N o r t~ h A m e_ rica _ -

The e a s t e r n p a r t o f N o r t h A m e r i c a i s a c o a s t a l g e o s y n c l i n e c o n t a i n i n g g r e a t t h i c k n e s s e s o f ? l a t e P a l e o z o i c , Mesozoic and C e n o z o i c s e d i m e n t s which s l o p e g e n t l y away ( s e a w a r d ) f r o m t h e c e n t r a l s t a b l e ( c r a t o n i c ) p o r t i o n o f t h e c o n t i n e n t (Murray, 1 9 6 1 ) . Cenozoic s e d i m e n t s a r e r e l a t i v e l y u n d i s t u r k d a n d u n d e r l i e a l o w - r e l i e f c o a s t a l p l a i n w h i c h e x t e n d s some 6 0 0 0 km f r o m n o r t h o f Newfoundland t o Honduras i n C e n t r a l America. The c o m b i n e d a v e r a g e w i d t h o f t h e emerged a n d submerged p o r t i o n of t h e p r o v i n c e i n t h e A t l a n t i c r e g i o n i s 2 5 0 km; a r o u n d t h e G u l f o f Plexico t h e a v e r a g e w i d t h d e c r e a s e s f r o m 600 km i n t h e U n i t e d S t a t e s t o 1 6 0 km i n Mexico ( T a m p i c o ) . To t h e s o u t h i t c o n t i n u e s to, n a r r o w a n d t h e n e x p a n d s t o n e a r l y 900 km i n w i d t h (N-S) t h r o u g h E l P i t e n ( G u a t e m a l a ) a n d Y u c a t a n P e n i n s u l a . The s e a w a r d b o u n d a r y o f t h e c o a s t a l p r o v i n c e i s p l a c e d a t t h e seaward-

392 f a c i n g s c a r p o r s l o p e o f t h e c o n t i n e n t a l s l o p e a n d r i s e (2. &.; see a l s o Hedberg, 1 97 6 ) . The c l a s s i c p i c t u r e t h a t t h e r e g i o n a l M e s o z o i c a n d C e n o z o i c s t r u c t u r a l e x p r e s s i o n of t h e c o a s t a l p r o v i n c e h a s b e e n c o n t r o l l e d b y g r a v i t y d o m i n a t e d d e f o r m a t i o n a n d t h a t s e d i m e n t a r y a l i g n m e n t s are a c c o r d a n t w i t h p r e s e n t day r e g i o n a l s t r u c t u r e ( M u r r a y , 1 9 6 1 ) h a s r e c e n t l y b e e n q u e s t i o n e d (Brown 2.: z?., 1 9 7 2 ) . In t h e v i e w o f t h e l a t t e r p r i n c i p a l v e r t i c a l m o b i l i t y h a s b e e n c a u s e d by b l o c k f a u l t i n g o r f l e x i n g , a c c o m p a n i e d by r o t a t i o n a l a l i g n m e n t of t h e a x e s o f p o s i t i v e a n d n e g a t i v e r e g i o n a l s t r u c t u r e s , and o c c u r r i n g c o n c o m i t a n t l y w i t h d i f f e r e n t i a l r a t e s of r e l a t i v e s u b s i d e n c e f o r c o a s t a l s e g m e n t s t h a t a r e j u x t a p o s e d a l o n g e l e m e n t s of a n i n t e r s e c t i n g h i n g e b e l t s y s t e m , c o m p o n e n t s o f w h i c h h a v e o n e of t h r e e p r i n c i p a l a l i g n m e n t s - NE-SW, 1 J W S E o r N - S . F i r s t and second o r d e r s t r a t i graphic u n i t s a r e then delineated. Cenozoic s e d i m e n t s of t h e Gulf a n d A t l a n t i c C o a s t a l p r o v i n c e s a r e p a r t o f a l a r g e g e o s y n c l i n a l s e d i m e n t a r y c o m p l e x of c o n t i n e n t a l , e s t u a r i n e , d e l t a i c a n d m a r i n e d e p o s i t s . The i n t e g r a l r e l a t i o n s h i p b e t w e e n b i o - a n d l i t h o f a c i e s h a s p e r h a p s nowhere b e e n b e t t e r d e m o n s t r a t e d t h a n i n t h i s complex r e g i o n where t h e c y c l i c a l , s e q u e n t i a l r e p l a c e m e n t o f one l i t h o t o p e b y a n o t h e r , h a s b e e n d e l i n e a t e d o v e r two g e n e r a t i o n s b y m i c r o p a l e o n t o l o g i s t s engaged i n commercial ( p e t r o l e u m ) e x p l o r a t i o n and S t a t e and U . S . G e o l o g i c a l Survey e x p l o r a t i o n s . S o r e 12-15,000 m e t e r s o f !lesozoic-Cenozoic s e d i m e n t s h a v e b e e n e s t i m a t e d t o o c c u r i n t h e Gulf C o a s t a n d 6 0 0 0 m e t e r s f o r t h e A t l a n t i c C o a s t ( r o u g h l y a 2 : l r a t i o ) b y ! l u r r a y ( 1 9 6 1 ) , b u t r e c e n t e s t i m a t e s b a s e d on s e a ward e x t r a u o l a t i o n s of o n s h o r e t h i c k e n i n g t r e n d s f o r s t r a t i g r a p h i c u n i t s i n S o r t h C a r o l i n a w e l l s s u g g e s t s t h a t t h i c k n e s s e s i n t h e two a r e a s may b e c o m p a r a b l e , on t h e o r d e r of 12-15 km (Brown 2' c:., 1 9 7 2 ) . In t h e A t l a n t i c C o a s t a l P l a i n C e n o z o i c s e q u e n c e c a r b o n a t e s p r e d o m i n a t e i n t h e s o u t h e r n h a l f , w h e r e a s m a r l s and c o n t i n e n t a l c l a s t i c s predominate i n t h e n o r t h e r n h a l f ( X a h e r , 1 9 7 1 ) . O u t c r o p s o f m a r i n e P a l e o g e n e a n d Neogene h a v e b e e n d r e d g e d i n s u b m a r i n e c a n y o n s a l o n g t h e e a s t c o a s t a n d on t h e Subsurface stratiB l a k e P l a t e a u - Bahama Banks r e g i o n a n d G e o r g e s Bank. g r a p h i c c o r r e l a t i o n o f t h e A t l a n t i c C o a s t a l P l a i n h a s r e c e n t l v b e e n compiled by Maher ( 1 9 7 1 ) , b a s e d on a n i n v e s t i g a t i o n o f numerous s t a t e s u r v e y w a t e r wells a n d t h e J O I D E S P h a s e I w e l l s (51-56) o f f t h e F l o r i d a C o a s t . E

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The C e n o z o i c t e c t o n i c e v o l u t i o n o f w e s t e r n E u r o p e h a s b e e n r e v i e w e d b y R u t t e n ( 1 9 6 9 ) a n d i t s ( b i 0 ) s t r a t i g r a p h i c e v o l u t i o n b v Brinkmann ( 1 9 6 0 ) a n d P o m e r o l (1972) on w h i c h w h o s e p u b l i c a t i o n s t h e f o l l o w i n g b r i e f summary is based. Because t h e p r e s e n t day c o a s t o f w e s t e r n Europe was e v o l v e d d u r i n g t h e Cenozoic, marine sediments a r e l i m i t e d l a r g e l y t o t h e v i c i n i t y of p r e s e n t c o a s t a l r e g i o n s , e x c e p t i n t h e A l p i n e r e g i o n (ex T e t h y s ) . Paleogene s e d i m e n t s c r o p o u t i n v a r i o u s b a s i n s e x t e n d i n g some 1500 km f r o m S c a n i a ( s o u t h e r n Sweden) t o t h e A q u i t a i n e B a s i n (SW F r a n c e ) a n d NW S p a i n , w h e r e a s Xeogene s e d i m e n t s o c c u r i n s c a t t e r e d s e q u e n c e s f r o m Denmark t o SW S p a i n . C e n t r a l E u r o p e may b e d i v i d e d i n t o two p r i m a r y z o n e s o f s u b s i d e n c e , a n €-I4 B a l t i c a n d a N-S R h e n i s h , a s t r u c t u r a l a l i g n m e n t w h i c h d e v e l o p e d i n the L a t e Permian. The N o r t h S e a a n d A n g l o - P a r i s - B e l g i a n b a s i n s w e r e i n e x i s t e n c e s i n c e t h e e a r l y M e s o z o i c ( J u r a s s i c ) . The l a t t e r f o r m e d a c o n t i n u o u s , i n t e r c o n n e c t e d zone of s u b s i d e n c e on t h e m a r g i n o f t h e F e n n o - S c a n d i a n s h i e l d t o t h e n o r t h a n d s e p a r a t e d f r o m t h e S o r t h German B a s i n by t h e A r d e n n e s - R h e n i s h M a s s i f a n d t h e Upper R h i n e R i d g e .

393 In P a l e o c e n e t i m e t h e f o r m e r l y u n i f i e d A n g l o - G a l l i c B a s i n w a s b r o k e n up i n t o s e v e r a l u n i t s - t h e London, H a m p s h i r e , P a r i s a n d B e l g i a n b a s i n s a n d become, p a l e o g e o g r a p h i c a l l y , a p a r t o f t h e same m a r i n e r e g i o n a s n o r t h e r n Germany. The S o r t h Sea B a s i n i s t h e m o s t p r o m i n e n t f e a t u r e i n t h e s e d i m e n t a r y h i s t o r y of w e s t e r n Europe n o r t h of t h e A l p i n e g e o s y n c l i n e . During i t s s e d i m e n t a r y h i s t o r y t r a n s v e r s e r i d g e s d i v i d e d i t i n t o s m a l l e r b a s i n s w h i c h were i n t e r m i t t e n t l y l i n k e d w i t h o n e a n o t h e r d u r i n g t h e Mesozoic and Cenozoic. S i g n i f i c a n t s u b s i d e n c e b e g a n i n t h e P a l e o c e n e i n t h e Nortll Sea Basin a s a r e s u l t o f t e n s i o n a l f o r c e s r e l a t e d t o t h e opening of t h e Xorwegian S e a . D u r i n g t h e Cenozoic t h e d e p o s i t i o n a l c e n t e r of t h e North Sea B a s i n was g r a d u a l l y d i s p l a c e d i n a n o r t h w a r d o r n o r t h w e s t e r l y d i r e c t i o n by t h e g r a d u a l r e t r e a t o f t h e sea f r o m t h e m a r g i n a l a r e a s o f n o r t h w e s t e r n E u r o p e . The g e n e r a l r e g r e s s i o n o f t h e s e a a n d d i f f e r e n t i a l t e c t o n i c s i n t h e d i f f e r e n t b a s i n s r e s u l t e d i n t h e termination of marine deposition i n t h e Anglo-Paris Basin a t t h e end of t h e Paleogene. The S o r t h S e a B a s i n i s t h e o n l y one i n which s e d i m e n t a t i o n h a s c o n t i n u e d t o t h e p r e s e n t t i m e . Linked i n t h e p a l e o g e o g r a p h i c s e n s e d u r i n g t h e P a l e o c e n e w i t h t h e North Sea B a s i n , t h e A n g l o - P a r i s - B e l g i a n b a s i n s h a v e b e e n e s s e n t i a l l y dormant f o r t h e p a s t 25 m i l l i o n y e a r s , a l t h o u g h p e r i o d i c s u b s i d e n c e d u r i n g t h e Neogene has r e s u l t e d i n s p o r a d i c , discontinuous sedimentary sequences i n these b a s i n s , p a r t i c u l a r l y d u r i n g t h e L a t e Miocene, P l i o c e n e and P l e i s t o c e n e . T h i c k n e s s e s o f C e n o z o i c s e d i m e n t a r y r o c k s r a n g e f r o m a b o u t 250 m i n t h e P a r i s B a s i n t o 800 m i n t h e H a m p s h i r e B a s i n t o o v e r 3000 m i n - t h e c e n t r a l p a r t of t h e North Sea. In SW E u r o p e m a r i n e C e n o z o i c s t r a t a o c c u r i n t h e A q u i t a i n e B a s i n o f SW F r a n c e , i n t h e t e c t o n i c a l l y a c t i v e c o a s t a l r e g i o n o f SW S p a i n a n d i n t h e Late Neogene G u a d a l q u i v i r B a s i n of SW S p a i n . S t r a t i g r a p h y was b o r n i n E u r o p e w i t h t h e i n v e s t i g a t i o n s of W i l l i a m Smith i n t h e e a r l y 1 9 t h c e n t u r y . The c l a s s i c s u b d i v i s i o n o f C e n o z o i c In p a r t i c u l a r , t h e m a r i n e s e d i m e n t s was o r i g i n a l l y d o n e i n w - s t e r n E u r o p e . c l a s s i c s u b d i v i s i o n o f t h e P a l e o g e n e i s b a s e d on m a r g i n a l m a r i n e s e q u e n c e s d e v e l o p e d i n t h e b a s i n s of NW E u r o p e ( L o n d o n , H a m p s h i r e , P a r i s , B e l g i a n , N o r t h G e r m a n ) , w h e r e i n d i v i d u a l s t a g e u n i t s a r e g e n e r a l l y i d e n t i f i e d with m a r i n e t r a n s g r e s s i o n s and c o n c o m i t a n t c h a n g e s i n b i o t a . Deeper w a t e r P a l e o g e n e s e d i m e n t s a r e e x p o s e d i n t h e A q u i t a i n e B a s i n (SW F r a n c e ) a n d a l o n g t h e Yh’ c o a s t o f S p a i n . Neogene d e p o s i t s a r e r a r e a n d p o o r l y e x p o s e d i n t h e m a r g i n a l a r e a s o f w z s t e r n E u r o p e e x c e p t i n t h e E-W s t r i k i n g l i n e a r r e e n t r a n t o f t h e A t l a n t i c Ucean i n t h e G u a d a l q u i v i r B a s i n - i n SW S p a i n . A s a r e s u l t , m o s t o f t h e Neogene s t r a t o t y p e s e c t i o n s a r e l o c a t e d i n t h e more compl et e s e q u e n c e s d e v e l o p e d i n t h e X e d i t e r r a n e a n r e g i o n . For a r e l a t i v e l y u p - t o - d a t e summary o f T e r t i a r y s t r a t i g r a p h y a n d r e l a t e d b o u n d a r y problems t h e i n t e r e s t e d r e a d e r i s r e f e r r e d t o aerggren ( 1 9 7 1 ) . PALEOGENE C e n o z o i c b i o g e o g r a p h y o f t h e N o r t h A t l a n t i c and m a r g i n a l ( i . e . a d j a c e n t ) l a n d areas i s i n t i m a t e l y r e l a t e d t o t h e c o n t i n u i n g p r o c e s s o f t h e fragmentation of L a u r a s i a . The o p e n i n g o f t h e X o r w e g i a n S e a d u r i n g t h e P a l e o g e n e a n d a t t e n d a n t s t r u c t u r a l r e o r g a n i z a t i o n o f t h e NE A t l a n t i c l e a d i n g t o t h e e v e n t u a l e s t a b l i s h m e n t o f an A r c t i c P r o v i n c e w i t h d i r e c t d e e p w a t e r connection t o t h e S o r t h A t l a n t i c r e s u l t e d i n d i s t i n c t f a u n a l changes a s a The o p e n i n g r e s u l t of t h e s e m o d i f i c a t i o n s t o l a n d and sea c o n f i g u r a t i o n s . o f t h e N o r t h A t l a n t i c t o t h e A r c t i c r e s u l t e d i n t h e f o r m a t i o n of North A t l a n t i c Deep Water, c o o l i n g o f s u r f a c e w a t e r s i n t h e N o r t h A t l a n t i c , enhanced l a t i t u d i n a l p r o v i n c i a l i z a t i o n of planktonic f o r a m i n i f e r a 1 faunas, s h a l l o w i n g o f t h e CCD ( a n d p r o b a b l e c o n c o m i t a n t c h a n g e s i n d i s t r i b u t i o n p a t t e r n s o f b a t h y a l b e n t h o n i c f o r a m i n i f e r a 1 f a u n a s ) and w i d e s p r e a d

394 d e v e l o p m e n t o f s h a l l o w , w a r m w a t e r . ' ~ , ~ : 4 ~ v ~ fLaiczieess d u r i n g t h e E o c e n e . S u p e r i m p o s e d upon t h e s e c h a n g e s w e r e t h o s e c a u s e d b y a g r a d u a l l o w e r i n g of t e m p e r a t u r e d u r i n g t h e Cenozoic and t h e g r a d u a l southward d i s p l a c e m e n t o f p a l e o l a t i t u d e s as t h e c r u s t moved n o r t h w a r d s o v e r t h e mantle. T h e r e h a s b e e n a n a p p r o x i m a t e l y 15"-20" s o u t h w a r d d i s p l a c e m e n t o f l a t i t u d e s i n t h e n o r t h e r n hemisphere d u r i n g t h e Cenozoic (Berggren and P h i l l i p s , 1971). One o f t h e m a j o r e v e n t s w h i c h a f f e c t e d P a l e o g e n e f o r a m i n i f e r a l e v o l u t i o n a n d b i o g e o g r a p h y w a s t h e s u d d e n a n d s i g n i f i c a n t 5°C c o o l i n g o f b o t t o m w a t e r s ( f r o m c?. 1 0 ° - 5 " C ) i n t h e S o u t h e r n Ocean ( K e n n e t t a n d S h a c k l e t o n , 1 9 7 6 ) n e a r t h e E o c e n e / O l i g o c e n e b o u n d a r y , c%. 38 ? l a , r e s u l t i n g i n t h e f o r m a t i o n o f t h e p s y c h r o s p h e r e ( s e e a l s o S a v i n e t aZ., 1 9 7 5 ) .

Planktonic Foraminifera The G u l f a n d A t l a n t i c C o a s t a l P l a i n P a l e o g e n e s u c c e s s i o n h a s b e e n p l a c e d w i t h i n a p l a n k t o n i c f o r a m i n i f e r a l b i o s t r a t i g r a p h i c framework by t h e s t u d i e s o f L o e b l i c h a n d T a p p a n ( 1 9 5 7 ) , O l s s o n ( 1 9 6 0 , 1 9 7 0 a , b ) , Eames eZ 9L. ( 1 9 6 2 ) , Blow ( 1 9 6 9 ) , a n d B a r k e r a n d Blow ( 1 9 7 6 ) , among o t h e r s . Similar s t u d i e s h a v e b e e n c o n d u c t e d on P a l e o g e n e s e d i m e n t s o f w e s t e r n E u r o p e b u t t h e f a u n a s t e n d t o b e p o o r e r owing t o t h e g e n e r a l l y s h a l l o w e r - w a t e r envirorrment o f d e p o s i t i o n . Paleogene p l a n k t o n i c f o r a m i n i f e r a l b i o s t r a t i g r a p h y and biogeography of t h e N o r t h A t l a n t i c h a s r e c e n t l y b e e n r e v i e w e d b y B e r g g r e n ( 1 9 7 2 , i n p r e s s ) a n d B e r g g r e n a n d H o l l i s t e r ( 1 9 7 4 ) s o t h a t o n l y a b r i e f summary i s presented here. E a r l y P a l e o c e n e (Danian) f a u n a s e x h i b i t morphologic c o n s e r v a t i s m , low d i v e r s i t y a n d g e o g r a p h i c c o s m o p o l i t a n i s m . D i s t i n c t d i v e r s i f i c a t i o n and p r o v i n c i a l i z a t i o n o c c u r r e d by m i d - P a l e o c e n e time a n d b y t h e e n d o f t h e Paleocene t h r e e d i s t i n c t , l a t i t u d i n a l l y - d i s t r i b u t e d assemblages a r e recognizable. S u b b o t i n i d s and globular-chambered a c a r i n i n i d s c h a r a c t e r i z e t h e high l a t i t u d e assemblages; middle l a t i t u d e s are c h a r a c t e r i z e d by s u b b o t i n i d s , a c a r i n i n i d s a n d m o r o z o v e l l i d s , w h e r e a s low l a t i t u d e s a r e c h a r a c t e r i z e d by a c a r i n i n i d s a n d m o r o z o v e l l i d s . T e m p e r a t u r e - r e l a t e d f l u c t u a t i o n s i n f a u n a l a s s o c i a t i o n s a r e seer. t h r o u g h o u t t h e r e m a i n d e r o f t h e Paleogene. The m o s t n o t i c e a b l e c h a n g e o c c u r s a t t h e e n d o f t h e E o c e n e a n d d u r i n g t h e E a r l y O l i g o c e n e when a m a r k e d f a u n a l r e p l a c e m e n t o c c u r r e d a c c o m p a n i e d b y l o w e r e d s p e c i e s d i v e r s i t y a n d t h e d e v e l o p m e n t o f two g r o u p s of m o r p h o l o g i c a l l y c o n s e r v a t i v e g l o b i g e r i n i d s , t h e "small" and " l a r g e " g l o b i g e r i n i d s , w h i c h c h a r a c t e r i z e d h i g h a n d low l a t i t u d e s , r e s p e c t i v e l y . G l o b i g e r i n i t i d s ( i n i z a : a , d i s s i r ; i i < s ) a n d g l o b o q u a d r i n i d s a r e common e l e m e n t s i n Upper O l i g o c e n e s e d i m e n t s i n t h e N o r t h A t l a n t i c . B e c a u s e o f t h e s p a r s e n e s s a n d / o r i r r e g u l a r d i s t r i b u t i o n of t h e f a u n a , a s t r i c t b i o s t r a t i g r a p h i c z o n a t i o n was n o t f o u n d p o s s i b l e i n t h e h i g h l a t i t u d e N o r t h A t l a n t i c P a l e o g e n e . More u s e f u l was a m u l t i p l e z o n a t i o n b a s e d on t h e a s s o c i a t i o n o f v a r i o u s f a u n a l e l e m e n t s . Only a n a p p r o x i m a t e c o r r e l a t i o n with the t r o p i c a l A t l a n t i c zonation i s possible. P a l e o g e n e p l a n k t o n i c f o r a m i n i f e r a l a s s e m b l a g e s i n t h e N o r t h Sea a r e c h a r a c t e r i z e d by a c a r i n i n i d s - s u b b o t i n i d s i n t h e Paleocene-Eocene a n d by In s m a l l g l o b i g e r i n i d s and non-keeled g l o b o r o t a l i i d s i n t h e O l i g o c e n e . t h e Norwegian-Greenland S e a , p l a n k t o n i c F o r a m i n i f e r a a r e r e l a t i v e l y s p a r s e d u r i n g t h e P a l e o g e n e ; Eocene f a u n a s c o n s i s t a l m o s t s o l e l y o f s j b b (S. sa:agcnica, S. :ir.ase:pta) a n d a f e w , s m a l l a c a r i n i n i d s .

395 Benthonic Foraminifera P a l e o g e n e s m a l l e r b e n t h o n i c f o r a m i n i f e r a l f a u n a s e x h i b i t a marked c o s m o p o l i t a n i s m w h i c h may b e e x p l a i n e d a s a r e s u l t o f w i d e s p r e a d e q u i t a b l e c l i m a t i c c o n d i t i o n s a n d low p o l a r - e q u a t o r i a l t h e r m a l g r a d i e n t s . I n t h e P a l e o c e n e t h r e e main d e p t h - c o n t r o l l e d b e n t h o n i c f o r a m i n i f e r a l a continental s h e l f fauna, assemblages ( i . e . f a c i e s ) have been recognized: t e r m e d t h e "Midway-type f a u n a " (PIF) , a c o n t i n e n t a l s l o p e a n d a b y s s a l p l a i n f a u n a , t h e " V e l a s c o - t y p e f a u n a " (VF), a n d a s h a l l o w , warm-water c a r b o n a t e s h e l f f a u n a , t h e " T e t h y a n c a r b o n a t e f a u n a " (TCF) ( B e r g g r e n a n d A u b e r t , 1 9 7 5 ) . The Midway f a u n a a c h i e v e d e s s e n t i a l l y w o r l d w i d e d i s t r i b u t i o n a n d o c c u r s i n A t l a n t i c P a l e o c e n e s e d i m e n t s a s f a r n o r t h a s 70"N L a t . ( E a s t e r n

l i n i d s ) , polymorphinids and t e x t u l a r i i d s . The " T e t h y a n c a r b o n a t e f a u n a " (TCF) i s c h a r a c t e r i z e d by d i s t i n c t

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of b o t h a s s e m b l a g e s o c c u r i n t h e C a r i b b e a n and M e d i t e r r a n e a n ( T e t h y a n ) regions. Elements of assemblage b) occur i n Paleocene s t r a t a of western Europe ( N e t h e r l a n d s ) . P a l e o g e n e s e d i m e n t a t i o n on t h e m a r g i n o f t h e N o r t h A t l a n t i c o c c u r r e d i n a s e r i e s of c y c l e s of t r a n s g r e s s i o n s and r e g r e s s i o n s . T h e s e a r e nowhere b e t t e r demonstrated t h a n i n t h e s t u d i e s on t h e b e n t h o n i c f o r a m i n i f e r a l f a u n a s o f t h e A n g l o - P a r i s B a s i n s ( W r i g h t a n d M u r r a y , 1 9 7 2 ; Murray a n d W r i g h t , 1 9 7 4 ) . These a u t h o r s grouped similar a s s e m b l a g e s i n t o q u a n t i t a t i v e l y d e f i n e d f a u n u l e s w h i c h w e r e t h e n u s e d t o compare d e p o s i t i o n a l h i s t o r i e s on t h e two s i d e s o f t h e E n g l i s h C h a n n e l : marginal marine environments ( n e a r s h o r e s h e l f , d e l t a i c m a r i n e , l a g o o n a l , f l - u v i o m a r i n e , and marsh) i n t h e Hampshire B a s i n and a r e g i o n o f e n c l o s e d s h a l l o w s h e l f , l a g o o n a l , l i t t o r a l e n v i r o n m e n t s of normal o r h y p e r s a l i n i t y i n t h e P a r i s B a s i n a n d W e s t e r n A p p r o a c h e s . hlarked f a u n a l d i f f e r e n c e s o c c u r b e t w e e n t h e two b a s i n s :

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t h e P a r i s B a s i n a n d p r e s e n t o n l y i n t h e Upper B r a c k l e s h a m b e d s (Upper L u t e t i a n o f t h e H a m p s h i r e B a s i n ) ; c ) a l t h o u g h t h e E o c e n e b e d s o f t h e P a r i s B a s i n a n d W e s t e r n A p p r o a c h e s h a v e many s p e c i e s s markedly d i f f e r e n t , i n common, t h e c o m p o s i t i o n o f t h e f a u n e . g . P a r i s B a s i n : ijmis.n, Z L p k < & : m , 'cides, polymorphinids (even i n m i l i o l i d dominated a s s e m b l a g e s ) ; Western Approaches: Pnrsratnik, J o z a X a ( i n m i l i o l i d d o m i n a t e d a s s e m b l a g e s ) ; d ) some

396 s p e c i e s which o c c u r t y p i c a l l y i n t h e P a r i s B a s i n o c c u r b r i e f l y i n t h e H a m p s h i r e B a s i n i n Upper B r a c k l e s h a m b e d s ( F i s h e r b e d s X V I I /

21). On t h e o t h e r h a n d , ,r,:Ls::;as a n d ";sc<s:C?ee were snown t o h a v e s i m i l a r d i s t r i b u t i o n s t o t h e two a r e a s . A d i s t i n c t d e p e n d e n c e o f t h e a s s e m b l a g e s on l i t h o t o p e i s p o s t u l a t e d i n t h e t h r e e a r e a s . Thus, i n t h e H a m p s h i r e B a s i n r i v e r s d r a i n e d J u r a s s i c Cretaceous sediments with l a r g e c l a y content. In t h e P a r i s B a s i n r i v e r s drained massifs with l i t t l e clay content. Sea-grass and shallow water a t t a c h e d forms f l o u r i s h e d i n t h e r e s u l t i n g c l e a r w a t e r . I n t h e Western A p p r o a c h e s a n d C o n t e n t i n t h e low s e d i m e n t i n p u t a l s o r e s u l t e d i n c l e a r , s h a l l o w w a t e r i n which s e a - g r a s s , b r y o z o a n s , and c a l c a r e o u s a l g a e f l o u r i s h e d . The d i s t r i b u t i o n o f s e a - g r a s s was c o n s i d e r e d a m a j o r f a c t o r i n c o n t r o l l i n g t h e d i s t r i b u t i o n of benthonic Foraminifera. The g r e a t e r a m o u n t s o f f r e s h w a t e r e n t e r i n g t h e H a m p s h i r e B a s i n a r e r e f l e c t e d i n e s t i m a t e s o f h y p o s a l i n i t y (32-33 " / o o ) t h e r e v s . n o r m a l s a l i n i t y f o r t h e P a r i s B a s i n . During m i d d l e Eocene t i m e s a l i n i t i e s i n t h e (Cr 8 , peneP a r i s B a s i n - C o n t e n t i n r e g i o n may h a v e r e a c h e d 3 8 roplids). Summer t e m p e r a t u r e s i n e x c e s s o f 2 2 ° C a r e a l s o s u g g e s t e d b y t h e s e f a u n a s . A d d i t i o n a l i n f o r m a t i o n on t h e P a l e o g e n e b i o s t r a t i g r a p h y a n d biogeography of t h e Anglo-Paris Basin ( i n c l u d i n g f o r a m i n i f e r a l d a t a ) can be found i n t h e t h o r o u g h r e v i e w s by C u r r y ( 1 9 6 5 , 1 9 6 6 ) . A d d i t i o n a l d a t a on t h e Paleogene b e n t h o n i c f o r a m i n i f e r a l b i o s t r a t i g r a p h y a n d p a l e o e c o l o g y o f NW E u r o p e may b e f o u n d in t h e s t u d i e s on t h e Eocene ( K a a s c h i e t e r , 1 9 6 1 ) a n d O l i g o c e n e ( B a t j e s , 1 9 5 8 ) o f B e l e i u m a n d t h e Mid-(Ulleberg, 1 9 7 4 ) and Late ( L a r s e n a n d D i n s e n , 1959) O l i g o c e n e of Denmark. I n g e n e r a l t h e l a g o o n a l - n e r i t i c n a t u r e o f t h e s e f a u n a l assemb l a g e s r e f l e c t t h e c o n t i n u i t y through t h e P a l e o g e n e of f l u c t u a t i n g , margina l d e p o s i t i o n a l c o n d i t i o n s a l o n g t h e Nh' E u r o p e a n c o a s t a l a r e a s . P a l e o c e n e d e e p w a t e r b e n t h o n i c f o r a m i n i f e r a l f a u n a s a r e known f r o m s e v e r a l t e c t o n i c a l l y a c t i v e b a s i n s on t h e p e r i m e t e r o f t h e A t l a n t i c i n E a s t e r n Mexico ( B a r k e r a n d B e r g g r e n , i n p r e s s ) , a n d t h e C a r i b b e a n ( T r i n i d a d , Venezuela, e t c . ) . T h e i r taxonomy, s t r a t i g r a p h i c a n d b i o g e o g r a p h i c d i s t r i b u t i o n i n t h e deep A t l a n t i c O c e a n a r e c u r r e n t l y b e i n g s t u d i e d by R . C . T j a l s m a ( W . H . O . I . ; s e e a l s o T j a l s m a a n d Lohmann, 1 9 7 5 , i n p r e s s ; Lohmann a n d T j a l s m a , 1 9 7 5 , i n p r e s s ) . F o u r m a j o r a s s e m b l a g e s were d i s t i n g u i s h e d b y a p r i n c i p a l c o m p o n e n t a n a l y s i s . T h r e e o f t h e m c o n t a i n a d i v e r s e , c a l c a r e o u s f a u n a a n d were f o u n d t o b e r e s t r i c t e d t o a p e l a g i c s e d i m e n t a r y e n v i r o n m e n t . They a r e :

8

~ y ~ < ~ si vi .. C - . f l v a- s ' ?s e m b l a g e

The f o u r t h , Smcoi.h = Montian).

Mme Damotte (1964)

was able to recognise the lower two in the Faris Basin, so they probably have a regional significance. zones in the zonal scheme given below.

They form the three lowest The 'eelandian fauna of

;>enmarkis not very well known, although ostracods have been listed by leroo and some described by Triebel.

Particular importance is

placed on the presence of ?aracgtheretta reticosa Triebel, which is also present in the Thanet Beds of Kent and the Palaeocene of noland (5ecezechura, 1965).

The ostracods of the i:zbles de

Brachcux of the Paris Basin 3re the only Upper Palseocene fauna to it is difficult to know how many of its species are truly indigenous. Of 26 doscribed be described in detail from western %rope,

so

species (!.postolescu, 1956) only three are present in the Thmet Beds. in particular, the Hszelina of the Thanct Beds (undescribed species) is not the same as that of the Crbles de Brachcux, "?uriana" sculpta.ADO:,T3LXSCU, while the absence of P.reticosa from the lables de Br?.chcux is considered important, although bearing in mind that .this m?.y be due to geographical factors, i.e., it may be

a

northern "cold watert'species.

However, the evidence

470

sugg5st.; that thi Thanetian of the Taris Basin is rath-r younger thsn the typa ;hanet Beds. shoxz in ?ext Pig. 3.

7h.i distribution of lmportant specles are

Moraeleberir conaliculata (APOST.) Opimocythere incis0 (APOST.) Clithrocytheridea mogna APOST. Cytheroptemn thilienrir APOST. Cytheretto new0 montenrir MARLIERE m o l l f a n . Cytheretta newa montenrir MARLIERE large f o n . Cytheretto news newa APOST. Parocytherette reticora TRIEBEL

.

Limburgino longiparoceo (DEROO) Liniburgincl arnobide(la firwrata DEROO bmantino stelloto DEROO Paleomonmirabilia geulenrir DEROO Limburgi no bi lame Ilom bi lame Ilosa (MAR LI ERE) Krithe montensir DEROO Boirdio montensir MARLIERE Cytherellcl montenrir MARLIERE Cythere I lo logenalir MAR LlERE

Fig.3.

Distribution o f ostracods in the Palaeocene of Europe.

The marine Thanetian is succeeded by continental deposits with a Vetustocytheridea lignitarum DOLLE1US (=V.guitrancourtensis AP0‘:T. ) , found throughout northern France, southern England, and possibly in northern hquitaine. Other important species are Neocgprideis durocortoriensis APOST. and Cgtheromorpha aillyensis BIGNOT. Palaeocene faunas have been described from the north and south of the Pyrenees (Tambareau 1972, Ducasse 1972, Tambareau et Villatte 1974). The “Lower Thanetian” has a poorly preserved marine

471 o s t r a c o d fauna.

The "Upper Thanetian" h a s a b r a c k i s h water fauna

i n i t s lowest beds, with Vetustocytheridea sp.,

Cytheromorpha a f f .

a i l l y e n s i s , and Neoc.yprideis m a n d i n a t u s TAIBARIUU.

The l a t t e r i s

o f great importance b e c a u s e i t i s i n t e r m e d i a r y between t h e M a a s t r i c h t i a n N.murciensis DAXOTT", F F FQURCADE and N . d u r o c o r t o r i e n s i s . T h i s is t a k e n t o r e p r e s e n t zone 1 o f I h e Ducasse ( 1 9 7 2 ) d e s c r i b e d from Campo i n n o r t h e r n Spain (see Text F i g . 2 ) .

The upper p a r t o f

t h e T h a n e t i a n of t h e P y r e n e e s c o n t a i n s a n u n d e s c r i b e d marine f a u n a , w i t h two s p e c i e s r e l a t e d t o T o l i s h P a l a e o c e n e o s t r a c o d s : cf

Kingmaina

opima. 5ZCEZECHUXA and T r a c h y l e b e r i d e a a f f . semiplana SCZZECHURA.

; h e Yucasse ( 1 9 7 2 ) h a s a l s o d e s c r i b e d I l e r d i a n f a u n a s , d i s c u s s e d below under t h e Eocsne.

!m :e

Ezcezechura (1971) h a s d e s c r i b e d a l a r g e Lower Palaeocene

fauna from V e s t e r n Greenland. many unassigned.

Thirty nine species a r e i l l u s t r a t e d ,

The fauna cannot be r e l a t e d t o any i n North

America o r Thrope. O s t r a c o d s from t h e Canian B r i g h t s e a t Formation o f IJaryland have been d e s c r i b e d by Hazel (1?68), where r e f e r e n c e t o o t h e r works may be seen.

The f a u n a , c o n s i s t i n g of t h i r t y f i v e s p e c i e s , i s v e r y

d i s t i n c t i v e , h a v i n g l i t t l e in common w i t h t h e o v e r l y i n g A p i a Formation, b u t w i t h t h i r t e e n s p e c i e s p r e s e n t i n v a r i o u s Lower '3alaeocene Gulf Coast l o c a l i t i e s .

The o s t r a c o d s i n d i c a t e

c o r r e l a t i o n wi-th t h e upper p a r t s o f t h e K i n c a i d Formation o f Texas and ?.he Clayton Formation o f 8lr,bama.

The f a u n a i s dominated

V e s t u s t o c y t h e r i d e a and Opimocythere, i n d i c a t i n g s h a l l o w marine i n n e r e u b l i t t o r a i conditions.

The p r e s e n c e o f V e t u s t o c y t h e r i d e a on

both s i d e s o f th.c A t l a n t i c i s i n t e r e s t i n g ; thc, i a r l i e s t s p e c i e s , V . f o r n i c a t a

Hazel p o i n t s o u t t h a t

f o r n i c a t a (.4L

similar t o H a p l o c y t h e r i d e a , and s u g g e s t s i t evolved from t h e l a t t e r . H a p l o c y t h e r i d c a i s a v e r y common g m u s i n t h e C r e t a c e o u s and T e r t i a r y o f ii.hmerica, t h a t Vetustocgthsridea,

b u t is r a r e i n m o p e . a'

So i t i s p r o b a b l e

s h a l l o w marine and b r a c k i s h w a t e r o s t r a c o d

somshow m i g r a t e d a c r o s s t h ? 4 t l a n t i c t o LGrops, p o s s i b l y v i a GrePnland where t h e ocean was narrow p r i o r t o ocean f l o o r s p r m d i n g ? The :?quia Formation i s p r o b a b l y o f idontisn a g e i n p a r t , as v h l l as i n c l u d i n g younger members, and c o n t a i n s s l a r g e and 3 , i s t i n c t i v e fauna.

3ne s p e c i e s o f i n t e r e s t i s t h a t r e f e r r e d t o

by Hazel as : < o c y t h e r o p t ? r o n a f f . t h i l i e n s i s A?3ET.,

originally

d e s c r i b e d from t h e S a b l e s d e Bracheux o f t h e ;Jaris Basin.

Pooser

412

(1965) has described the fauna of the Black ;dingo Formation of South Carolina which suggest that the formation straddles the Palaeocene-Xocene boundary, most of it being Eocene. He recognised tuo assemblage zones, Brachycythere interrasilis A L X X A N D B and Cytherelloidea nanafaliensis HOI:.'F, which could represent differences in age, environment, o r both. The distribution of some common Palaaocene and Eocene species from the Atlantic coast are shown in Text Fig.4.

I

Y

i U. EOCENE

I 1

M. EOCENE

L!

EOCENE

ACUIA PALAEOCENE BRIGHTSEAT

7I T I +

Fig.4. Distribution o f ostracods in the Palaeogene of eastern U.S.A.

Eocene faunas have been described by Apostolescu (1955, 1956), Haskins (1968-72) and Keij (1957). The base of the Ypresian stage is taken to define the base of the Xocene, which lies within zone P6. This stage is represented by the London Clay and Argiles d'Ypres. Three subeones can be recognised (Text Fig.2) in England and Belgium, although it is not clear to what extent these are facies controlled. The fauna is very characteristic, with a deeper water element represented by Brachycythere triangularis REUSS, Tchinocythereis reticulatissum

473 E 4 G A R l Krithc londinensis JONE2, and Trachyleberidea prestwichiana (JONES AiU’3 BHZRBORN)

(JONEE)

,

, shallower water

by Cytheretta scrobiculoplicata Hazelina aranca (JONES A m CRERBORN) , Pterygocytheris

laminosa HASKIN’?, Zchuleridea perforata insignis ( J O N E ) and Trachyleberis spiniferimma ( cJOIJE‘J Aim SHFBBORN) , and coastal waters by Zytheridea primitia H.44CKIBS and Cytheridea newburyensis GOKCEX. The faunas have been described by Xagar ( 1 9 6 5 ) , Gokcen ( 1 3 7 1 ) , Haskins (1968-72), and Hillems (1975 ). Tho Cuisian substage of the Paris Basin contains a rich fauna (.4postolsscu, 1956) including Novoc.ypris whitecliffensis (HAZKIWS). This species first appears in the Zables de Mons-en-Frevele of Belgium with a fauna more characteristic of the London Clay, but lacking Cytheretta scrobiculoplicata.

Novocypris is a genus more

typical of the Aquitaine Basin. In Spain and Lquitaine the Ilerdian spans the PalaeoceneEocene boundary. Xme 3ucasse recognised three ostracod biozones from Camp0 in northern ?pain for the Ilerdian, numbered 2, 3, and 4 on Text Fig.2. The lowest zone is characterised by a littoral marine fauna with genera such as Bairdoppilata, Pokornyella, and Guadracythere. The middle zone is characterised by a deep shelf or continental slope fauna, with Cytherella consueta DELTEL, Echinocythereis, Krithe, and Pontocyprella aturica DELTXL. The two species of Idlle Peltel are found in many Tertiary deep water The upper zone marks a return to shallower deposits of Iquitaine. water.

Throughout the ?yrenean area the base of the Ilerdian is

marked by the appearance of Pokornyella citrea TAMBIBAREAU often accompanied by Rchinocytheris isabenana DFXTLI (Tambareau, 1972). Biozone 5 of Ducasse (1972) is equated with the Cuisian and the first appearance of Novocypris eocaenica l’lUCAS5Ein northern Spain, although this species occurred earlier in northern Aquitaine. The Xiddle Eocene commences with the Lutetian stage. The oldest ostracod fauna recognised so far is found in Fisher Jed 1 of Bracklesham ( = lowest Fisher Bed VI of Khitecliff Bay; the numerical subdivisions on Text Pig.2 are the Fisher Beds of Khitecliff Bay), but the fauna is undescribed. -4bove this, the ostracod zone Ob contains the typical Lutetian fauna seen in the This subzone sees the first Paris Basin (Apostolescu, 1355). appearance of Cytherelloidea damariacensis APOSTOLESCU,

474

'tergpocythcrzis 'i'i?Z:;BEL,

cornuta ( R O E X E R ) , Schixocythere appendiculata

Schuleridea perforata perforata ( R O ? X 8 ) and other species

indicated on Text 7ig.5. A major evolutionary radiation CM be recognised amongst the ostracods at this time (Keen 197Zc). The upper part of the Lutetian, correlated with the Biarritzian, is marked by the appearance of Cythoridea ripida rigida HASKINS (Text

This species, together with Cgtheretta forticosta K D J T and Fig. 5). Xchinocgthereis scabropapulosa JONES, differentiate ostracod Zone 9 from 8b. All three are present in Zone 10, but accompanied by descendants of Cgtheretta eocaenica KFIJ: Cytheretta cellulosa K T X and Cytheretta carita K,GN; and a descendant of Cytheretta costellata costellata BOSCUGT, C.costel1ata grandipora K W J .

-

w I I

I

Fig.5.

I

I

Distribution o f ostracods i n the Bracklesham Beds of England.

475

The Upper Zocene is equated with the Bartonian, where t w o ostracod zones can be distinguished.

The lower is characterised by

Cytheretta laticosta RELJSS, Cgtheridea intermedia RCLJSS, and Pterygocythereis bartonensis K T I J , all restricted to this zone. The fauna can be recognised in the Barton Clay and in the Xarnes

a

Pholadomya ludensis in the Paris Basin, but appears to be absent in Belgium.

The upper zone contains freshwater, brackish, and marine

horizons, and is characterised by an endemic fauna in southern ngland

.

In northern Aquitaine Mme 3ucasse (1969) has recognised eight biozones for the tocene (Text Fig.2).

These are really assemblage

zones, and to a certain extent reflect environmental conditions. HoTxever, they have proved useful for correlation over a limited area, Many of the species are present in the Anglo-Paris-Belgium area, but have more extensive ranges, thus thro:.:ing some doubt on their iientification.

On the whole, these zones are not easy to correlate

with northdrn Europe.

Faunas from the Western Approaches and the

Xnglish Channel will probably prove helpful in correlating ?pitainn and more northerly regions.

-3.

fauna recfntly describad from thz?

Loire valley near Nantes (Blondeau, 1971) probably belongs to the Cytheretta cellulona zone, and may provide a link with Aquitaine. Typical Atlantic coast "iocene ostracods are listed in 'i'ext Fig.4.

The main Lor;er Yoceni-:fauna is that describt;d by 'ooser

(1965) from the Black ldingo Formation of Eouth Carolinri and from boreholes in North Carolina by "wain ( 1951). been discussed under the Palaeocene.

The former has alreiidy

?coser also describ9d a rich

I.Iid51e 9occn? fauna from the Warley Hill ipormstion snd ?antes Limectone.

From the former he recorded Trzchyleberis spinosissima

(Jonas an? :herborn)

which he regards as a s m i o r synonym of

T.s?iniferrima ( J 3 N T >.NE cX?ZB~R€J); it was suggested that the locality yielding this species was probably older than most k.'arlr:y Hill localities.

If the identification is correct, it suggests a

l o w r Xocens age as this cpscies is typical of the London Clay, belonging to ostracod zone 6b-c.

Xost of the Iv~iddlc.Eocene ostracods

arc? also found in the Upper Eocene, and ind-ed are typical of the Jacksonion stage of the Gulf Coast.

The Upper Yoczne is difficult

to recognise in the ostracod faunas of the Atlantic coast, but is probably represented by part of th? Cooper Marl

476

OLIGOCFSJE There has been a great deal of debate in recent years over the position of the Eocene-Oligocene boundary.

In the Paris Basin there

is a marked faunal break between the Ludian Marnes ‘a P.ludensis and Marnes h Lucina inornata on the one hand and the Sannoidan on the other: of 27 Sannoisian and some 30 Ludian species none are found in common (Keen, 1972a). In England a similar break is seen between the marine Middle Head.on Beds and the Upper Hamstead Beds, the latter containing 13 species all of which are present in the Sannoisian or Rupelian of the Paris Basin. This Sannoisian fauna is also present in Belgium.

The difficulty is in correlating these

beds with the Lattorfian, which defines the base of the Oligocene. The presence of the typical Sannoisian ostracod Hemicyprideis montosa JONES PiNn SHmBORN just below the freshwater Bembridge Limestone of %gland and the Lattorfian Quadracythere diversinodosa (LIENENKLAUS) just above the limestone suggests that the Bembridge Beds might be correlated with the Lattorfian (Text Fig.2). Certainly thr Middle Headon Beds have a strong affinity with the Barton Beds (Keen, 1968). The Rupelian has a very distinctive ostracod fauna (the Sannoisian is regarded as a facies of the Lower Rupelian), with little in common with older faunas or with the Lattorfian.

Several of the species are present in Aquitaine,

allowing accurate correlation. The Upper Oligocene is only really seen in Aquitaine if the study is restricted to the Atlantic seaboard. Here, the Couches h Phare St. Martin at Biarritz contain several species found in the Chattian of Germany and Switzerland, including Flexus gutzwilleri (OTRTLI)

.

477

HAMSTEAD

1

13b

HEADON

I Fig.6.

Distribution of ostracods i n the Upper Eocene and Oligocene of England.

Along t h e e a s t e r n seaboard of N.Amsrica no Oligocene strata a r e d e f i n i t e l y present.

Swain has suggested t h a t C y t h e r e t t a howei

?MAIN might be t y p i c a l f o r t h e Oligocene, but t h e age of t h e rocks c o n t a i n i n g i t a r e not c l e a r .

Pooser placed t h e Cooper Marl i n t h e

Oligocene, but t h e fauna he r e c o r d s seems t o i n d i c a t e two a g e s , Upper Zocene and Miocene. Cytheretta alexander,

HOP!?

HOl,:K

The o l d e r group of samples c o n t a i n s & CHUIBYRC, Haplocytheridert montgomerxensis

& CH4iE3l.RS and Trachyleberis f l o r i e n s i s (HO!XE & CHAKEGRT,) which

s t r o n g l y suggest a Jacksonian age, i.e.

Upper Eoccne.

Pooser

suggests t h i s might c o n s t i t u t e a s e p a r a t e b i o s t r a t i g r a p h i c a l u n i t . The same fauna i s a l s o recorded from a l o c a l i t y r e f e r r e d t o t h e Miocene Duplin Marl by ?ooser, and t h i s u n i t must a l s o be Upper n

:'>ocene.

The younger assemblage, which i s more t y p i c a l of t h e

Cooper Marl, xas r e f e r r e d t o t h e Henrghowella evax Assemblage Zone, and t h e s p e c i e s l i s t e d suggest a Miocene age.

In f a c t , t h e main

reason f o r an Oligocme age was t h e apparent overlap of Eocene and

418 Tdiocene s p e c i e s , which i s o b v i o u s l y removed i f two d i f f e r e n t f a u n a s from two d i f f e r e n t h o r i z o n s a r e p r e s e n t . NS0G”NE

O s t r a c o d f a u n a s o f t h i s a g e have been d e s c r i b e d from s o u t h e r n She c o n t r o v e r s i a l l o c a l i t y o f Escornbgou i n s o u t h e r n

France.

A q u i t a i n e h a s y i e l d e d a r i c h f a u n a w i t h some s p e c i e s i n common w i t h t h e C h a t t i a n o f B i a r r i t z , Germany, and S w i t z e r l a n d b u t a l s o w i t h many s p e c i e s u s u a l l y r e g a r d e d as t y p i c a l l y Miocene: c a n a l i c u l a t a :REIJ

, Cnestocgthere

truncata

Callistocgthsre

(RE%?),

t r i - o s t a t a (RT.Jc~c), and Iismicythere d e f o r m i s (RXJUF,S).

:>!any o f t h e

apeci?s are p r c s m t i n t h e c l a s s i c l o c a l i t i e s of n o r t h e r n Aquitaine, b u t ~ i o m e t y p i c a l Xiocene g e n e r a s u c h as A u r i l a and ? u r i a n a a r e ‘?he Fscornb4ou h o r i z o n i s u n l o u b t e d l y o l d e r t h a n t h e t y p e

abypnt,

. i t a i n i a n , F O i f t h a l a t t e r d e f i n e s t h e base of t h e Miocene, ,,scornbeoa mu--t b s o f Oligocenr: age. ? h > ? > q u i t a i n i a nand younger o s t r a c o d f a u n a s o f t h e t y p e a r e a have bqen t h o r o u g h l y d e s c r i b e d by :Coyc?s (1965’1.

He found t h a t t h e

d i s t r i b u t i o n o f many s p e c i e s was s t r o n g l y i n f l u e n c e d by t h e changes . c i t h i n a shal‘io;. c o a s t ? ? environment, so i t was n o t e a s y t o

ii f f e r e n t i a t f t h ? c l a s s i c a l stagrs.

The Lower [diocene ( A q u i t a n i a n

- Burdigslian’t form-d on? u n i t w h i l e th; Upper Miocene could be divide! i n t o t

30.

1969)

Carborx1.l (

The P l i o c a n e i s m o s t l y u n f o s s i l i f e r o u s . Ctudi-d t h e o s t r a c o d s o f t h e Miocene o f th-? ?hone

Vali-:y and *):as a h a - t o r e c o g n i s e f o u r b i o z o n e s which a r e d i s c u s s e d i n t h . n-xt s e c t i o n .

Thc :dioc.snc: s t r a t a o f t h e e a s t e r n U.5.B.

out.crop from F l o r i d a

t o :krylan:! and have y i s l 4 e d a v e r y r i c h f a u n a , d e s c r i b e d by s u c h a u t h o r s as LTirich & Basnler, HOWF:, i!IcLnan, and ?uri.

Xany o f t h e

Ypncier,: h a v s a l o n g s t r a t i g r a p h i c a l r a n g e w i t h s s v e r a l s t i l l l i v i n g . !iox;;”ver, by u s i n g a s e m b l a g n s i: i s p o s s i b l e t o u s e t h e o s t r a c o d s i n

?mi ( l 9 5 , ? ) h a s i n d i c a t e d t h a t s p e c i e s o f C y t h c r e t t a

corr-istion.

hav-? v e r y l i m i t e i s t r a t i g r a p h i c a l r a n g e s and a r e i d e a l as z o n a i fo=iil?.

T h e i r ta:ionorny d o e s need s o r t i n g o u t though.

r i c a n Zyth5rL:tta