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Photographs Front of cover Ceratoichthys pinnatiformis, Verona Museum.
Back of cover Top Left: Rhamphosus acu/eatus...
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Photographs Front of cover Ceratoichthys pinnatiformis, Verona Museum.
Back of cover Top Left: Rhamphosus acu/eatus, Verona M. Top Right: Pygaeus gazo/ai, Verona Museum. Bottom Left: Acanthura ova/is, Verona Museum.
Title page (opposite) Priscacara /iops, Eocene, Wyoming, (50 million years), Baensch Collection. All rights reserved. No part of this book may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopyinQl, recording, or by any other information storage and retrieval system, without
Karl Albert Frickhinger
Fossil Atlas Fishes
written permission of the publisher, except where permitted by law. Library of Congress Cata:loging-in-Publication Data
Translated by Dr. R. P. S. Jefferies, London
Frickhinger, Karl Albert [Fossilien Atlas Fische, English) Fossil atlas, fishes / Karl Frickhinger; translated by R. P. S. Jefferies. 1st English language ed. 1088 p. 12 x 18 cm Includes bibliographical references (30 p.) and indexes. ISBN 1-56465-115-0 1. Fishes, Fossil - Atlas. 1. Title QE851.F89213 1995 95-138
567'.022'3--dc20
CIP 1st. Edition, 1995 ISBN 1-56465-115-0 (U.S.A. only) ISBN 3-88244-019-8 (for other countries) WL Code 16822
© Copyright 1991, 1995 Mergus® Verlag GmbH, Hans A. Baensch, P. O. Box 86, 49302 Melle
Mergus ® is a registered trademark.
Layout:
Dr. Gero W. Fischer, Quito, Ecuador
Lithography:
bucher- repro, Bielefeld, Germany
Press:
Mergus Press, Singapore
Editor:
K. A. Frickhinger, Munchen, Germany
Original Publisher:
Hans A. Baensch, Melle, Germany
1st English Language Ed., 1995 Published in the USA:
Tetra Press, Blacksburg, VA
Distribution: USA:
Tetra Sales (Warner-Lam bert-Company) Blacksburg, VA 24060
Canada:
Rolf C. Hagen Inc., 3225 Sartelon Street, Montreal, Que. H4R 1E8
Great Britain:
Rolf C. Hagen (UK) Limited, California Drive, Whitwood Industrial Estate, Castleford WF 10 50H, West Yorkshire
Australia:
Pets International Pty. Ltd., 5 Orchard Ind. Est., Orchard Road, P. O. Box 21, Chester Hill, N.S.w. Pet Pacific Pty. Ltd., Unit C, 30 Skarratt Street, Auburn N.S.w 2144 P. O. Box 398, Rydalmere N.S.W. 2116
Printed in Singapore
Publishers for Natural History and Pet Books Hans A. Baensch
•
Melle
•
Germany
Preface
Preface There is no lack of general literature on fossil invertebrates. Am monites and trilobites, especially, have been very thoroughly treated in the last one hundred years and there are many texts available on faunas and particular systematic groups. Above all, there is the well known "Treatise on Invertebrate Paleontology" an available work that leaves very little to be desired. It is true that the last few years have given us "The Handbook of Palaeoichthyology" and "The Handbook of Palaeoherpetology". Unfortunately, however, neither work is complete and we may have to wait many years before all the volumes are available. More over, both are purely scientific works whose main objective is the diagnosis of genera. It is therefore understandable that they do not give as many figures as the editors and authors would no doubt have wished. Because of this, the readership is effectively restricted to scientific professionals and a few especially inter ested amateurs. Apart from these two important works, little choice remains. The vertebrate literature must be gathered laboriously together and all-inclusive works hardly exist. As to fish, the last and only tempt to record all known fossil fishes, and illustrate them with masterly engravings, was made by Agassiz. He wrote 150 years ago, however. Only a few complete copies are left and they fetch an extremely high price-more a book lover's rarity than a practi cal work. These considerations prompted me to produce the present work. It is a "picture book." I do not intend it to compete with more scientific works, since I knew from the start that it could be no more than a useful supplement to the specialised literature. Nevertheless, it was no easy task. I have visited most of the im portant museums in the world and suffered a great deal of drudg ery. I have searched through the collections for hours at a time, finally to photograph only those fishes still lacking. At first, every thing went quickly, but once I had reached a certain level, it be came more and more difficult to find anything new. Above all, I had set myself to photograph very well preserved specimens only. Thus I soon discovered that many of the 2500 genera so far de scribed were based on incomplete specimens only, or even on single dorsal shields, teeth, spines or scales. No doubt there is 4
rial to which I never had access or have over. muc h good mate however, could only be true 0f a fractlon 0f the genlooked. This, n this book. era show n i difficulty was the nomenclature . In many collecAnother great s old specimens labelled with antique synonyms, t·Ions I came acros . I have made great efforts to bnng even undetermined material. lists, speCia willing help of certain erything into order; with the eless, I cannot g� arantee ab Nevert . grateful to w hom I am very rely ask that, If the reader since I . solute correctness in all cases of it. finds a mistake, he tells me intended for? The scientific special book this is What readership ent to the technical literature. supplem ist may find in it a pictorial the fishes Besides that, he may be glad to know in what museum curator will be able, are kept which interest him. The museum discover using this book, to look over what is on offer and thus of student The d. expande how his collections may sensibly be fossil the palaeontology will be given a general view of most of fish fauna. The book will be of greatest interest to fossil collec tors. Finally, I do not forget the amateur , whether angler or aqua rist, who is interested in fishes. Up till now he has not had the chance to see what the ancestors of his fishes looked like, how they evolved nor how long they have already been on earth.
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Autumn, 1 994, Planegg.
5
Acknowledgements
Contents -
Preface
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Collecting Fossils ...... .. . . . . .. . . . . .. .. . . . . . .. . . ... .. . . .. . ..... .. . . .. . .. .... ... .. ... . . . . . . 11
The Photography of Fossils .... . . . . . . . . .. . . . . . . . . . .. . .... .. . ... . ... ............ . .... 13 Evolution in Geological Time . ... . . . . .. . .. . .. . . . . . . ... .. . . .. . .. .... .. 16-17 .
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The Origin of Life and the Evolution of Fishes .. . . . . . . . . . .. . . .. ... .. . 18 .
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The External Features of Fishes .. . . .. . .... . . .. .... . . ... . . . . . . . . ..... . . 26-33 .
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The Groups of Fishes . . . . .. .. . . .. .. . ... . ... . . . .. .. . . . . . . . .. . . .. ... . . . .. 68-994 .
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Agnath a
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(Jawles s Fishes) ... ... .... . .. . . . . . .. . . . ... . . . ... . .. . . .. . .. . 68 Placod� rmi (Placod erms) . .. ...... . . . . . .. .... . . . . .. . . ...... . .. ... . . . ... . . . 116 Chondnchthyes (Cartila ginous fishes) . . . .. .. . . . .. . . . ..... ... . .. . 147 Acantho dii (Acanth odians ) .. . . . . . . . .... . . .. .. ..... .. ... . . .. . . . . . . 236 ondros tei (Chon d rostean s) . . .... ... .. . . .. . .. . . . .. . . . . .. . . . . ... .. . . 252 olostei " (Holost eans) . .. .. .. . . . . .... . . . . . .. ... .... .. . . . . .. . . 371 Teleostei ( True Bony Fishes) . .. .... . . . ....... ..... . . . . .. . . ... 449 Euteleostei (Higher Bony Fishes) . . . . . . . . . .... ... . .... ... . . .. ... . . . .. 573 :oss?pterygii (Lobe-fin ned Fishes) .. . . .... . . .. . .. . . .... ... . .. .. 939 Ipnol (Lung Fishes) ... . . . . . . . ....... . ... .... . . . .... . . . .... . . .. . 975 .
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Index of Genera and Synonyms . ... . . ... . ..... ... . . . . ... . .. . . . . . .. 1027 .
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Index of Orders, Suborders, and Families . .
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Index of Genera, Arranged by Formation . . . . . . . . .. .. ... .. .. ...... . .... . 1059
Index of Genera, Arranged by Locality . . . . . ... . ...... . . . . . . .. . . . . . 1070 .
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Index of Recent Families and Genera .. ... . . .. . .. .... .
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The Author .. . . .. ... . . ... . . . . . . . . . . ... . .. . . ... .. . .
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d g reat person al and financ ial outlay , boo k, which involve have been finishe d withou t the most genero us hel p o d never I t is therefore a pleasant duty to thank all parts o f the worl d . who allowed me to photograph the institutes and the museu ms in their collections or made photograp hs avail nest specimens I would also like to thank all those who so able free of charge. my questions when anything was unclear to me. willingly answered grateful to Prof. Schultze, of Lawrenc e, Kansas , I am particularly whom I sometimes burdened U.S.A. and Dr. Patters on of London was especiall� hel�ful as advice ose wh and b eyond all reason . . , of M u n ich, likewise Wellnhofer concerns the new systematic s. Dr. to the firm deserves my special thanks. I am also deeply indebted not only who Sander, J Herr Director its and le, Mel of Tetrawerke, it. d but finance organi sed my MoscoW joumey
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Th'I
The followin g l ist is arranged alphabeticall y by town or city. Adelaide , Australia, Museum of Natural History, Dr. N. Pledge. Amsterdam, Netherlands , U n iversiteit van Amsterdam , Geolog i c a l Museum. Dr. J. H . Werner. Berg amo, Italy, Museo Civico di Scienze Naturali, Dr. Paganoni. Berli n , Museum fOr N aturkunde, Dr. Jager, Dr. W.-D. Heinrich . Bloemfon tein , South Africa, National M u seum, Dr. C. M. Engelbrecht, Dr. B. Rubidge. Brisbane, Australia. Queensland Museum, Dr. R. E. Molnar. Bristol , England, U niversity of Bristol, Prof. D. L. Dineley. Brussels, Belgium, I nstitut Royale des Sciences Naturelles de . Belgique, Dr. P. Sartenaar Calgary, Alberta, Canada, Geological S u rvey of Canada, Dr. R . Tho rsteinsson . Canberra, Australia, Australian N ational University, Prof. K. S. W. Camp be l l . Canberra, Australia, Division of Continental Geology, Dr. G. Young. Capetown, South Africa, South African Museum, Dr. M. A Cluver, Dr. R. Smith. Chicago, I l linois, U.S A. , Field Museum of Natural History, Dr. L. Grande, Dr. C. Forster. Cleveland, Ohio, U. S. A, Cleveland Museu m of Natural History, Dr. M. E. Williams, Dr. G. L. Jackson. Copenh agen, Denmark, Geological Museum, Dr. B. S. Bang, Dr. S . Bendix-Almgren. 7
Acknowledgements
Acknowledgements Drumhel ler, Alberta, Canada, Tyrel l Museum of Paleontology, Dr. D. Bri nkmann, Dr. Neumann . Edin burgh, Scotland, National Museu m o f Scotland, Dr. W . D. I . Rolfe, Dr. R. Patton. Edmonto n, Canada, University of Alberta, Prof. Dr. M. V. H. Wilson. Eichstatt, Germany, Jura-Mus eum, Willibalds burg, Dr. G . Viohl. Eichstatt-H a rthof, Germany , Museum Berger, Herr R . Berger. Frankfu �-am-Mai n , G ermany , Naturm u seum S enckenb erg , Prof. W. Ziegler, Dr. G. Plodowski, J. Oeliw
;
t re ults are normally got under artificial light since only this of illumination can be adapted to the requirements of the imen. Even so, very bright light must. as .a general rule,. b.e ed, for only a soft side light gives the desired results. ThiS IS a rticularly true of fossils that are hard to see, such as s�me ec ts. In such cases it is often important whether the light comes from left, right or above. Furthermore the nature of the rock must be taken into account, because some rocks reflect light while others absorb i strongly. In this connection, automatic exposure meters often give wrong answ ers. The photographic method used by me has aroused interest even among specialists. I work with a very simple tr ck�1 use p�lar . ized light. The light source must have a polariZing filter, as like wise the lens of the camera. By rotating these polarizers, all reflections can be cut out. At the same time, the specimen grows darker and thus more brightly coloured. By turning the polarizers back slightly, a minimum of reflections can be brought back, giving a more lively picture. When using this method, all disturbing outside light should be excluded. Since this can hardly be done with incident daylight except by photographing only at night-I use a blue filter over my light source. This allows me to employ daylight film with the benefit that the camera can quickly be used for other purposes. Film sensitivity should not be greater than 100-200 ASA (21 -24 DIN). I use Ektachrome Professional film. Unfortunately, even with a daylight filter, a slight trace of purple often intrudes which can be countered by using a weak green filter (Kodak Gelatine Filter G005). Using a light amber filter brings other advantages. Of course, by applying all these differ ent filters I lose at least three stops. It is therefore necessary to use a stand. Exposure times of 1 second are attainable in almost all cases.
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13
The Photography of Fossils As to exposure time, I have already mentioned that the charac teristics of the different rocks must be thought of. In this connec tion while black and red rocks need u nderexposure, grey rocks are, in general, neutral .
In the following table I give examples of how the exposu re meter
value should be modified in particular cases: Bolca Brazil Bunden bach Holzmaden Kupferschiefer Lebanon Messel Pfalz Red rocks Scottish Old Red Solnhofen Wyo ming
normal 1-2 stops more 1 stop less
1 stop less 1-2 stops less
1-2 stops more normal normal
1-2 stops more
normal
1-2 stops more 1-2 stops more
These are only a few examples. Other rocks can be interpolated as appropriate . And now for the camera itself. I recommend a small-frame cam era with an i nterchangeable lens and a double d raw tube. An
extension ring allows me an image magnification of 1: 1, which
has turned out to be enough in all cases. If a higher image magnification were needed, a bellows could be inserted.
All this sounds rather complicated and is not cheap to buy. But the results are well worth the trouble and expense . There is a paradoxical rule of t h u m b-l ight-coloured rocks req u i re over exposure.
1 4
Phylogeny -
Y QUATER N AR andTE RTIARY
W LJJ
•
o Z
a:
w
1 ---
-.J,
-.J
---
----1
____ _
� ffi §
- - N- I-AN- ---t- O I---O-EV I (j)
. -----+- LL 1--
I
0
0 :2:
?n27 I-----_+_ � 0 SILURIAN
OROOV ICIAN
CAMBRIAN
0....
-------1
PHYLOGENie TREE OF THE VERTEBRATES according to BARTHEL
15
Era
Period
Subdivisions (Epoch) Holocene (recent)
g8,
Wurm Glacial Riss Glacial Mindel Glacial
�8 0..0:::-
Gunz Glacial Pre-glacial
Gl c: Gl-
Quarternary 0
'0
N 0 C
'n; 0
(jict
Pliocene Miocene
Tertiary
Oligocene Eocene Palaeocene
Animals and Plants
Years· 10,000 50,000 200,000 500,000 700.000 2 millon
7 million 26 million 38 million
54 million 65 million
Pre-historic, historical and cultural evolution of man. The extinction animal and plant species by man's actMty begins and Increases.
of
The first true men. Climatic fluctuations caused by the ice ages change the fauna and nora.
Highest development of the mammals and the (angiospenns). Primates appear. Towards the enc
organisms
flowering plants the first man-flke
originate.
,.. .
=
� Evolution of reptiles up to enormous sizes (dinosaurs). The first
Cretaceous
birds appear. Ammontes develop strange forms. The first plants (angiosperms) appear. At the end of the period most
Upper Cretaceous
100 mINion advanced
lower Cretaceous
136 millon reptiles de out. Including the pterodactyts end ichthyosaurs. Ammo·
ftov.oering
niles and belemnites likewise disappear.
0
'0
N 0 UJ Q)
�
Jurassic
Uas
Triassic
t
*
Upper Jurassic Middle Jurassic
Keuper Muschelkalk Bunter
n. The numbers refer to the start of the period in questio
157 mHllon The acme
of the
reptHes. Including especia8y the pterodactyls and the
172 million ichthyosaIxs. Appearance of the primitive bird AIchaeopteryx. Plants 190 million not much changed.
205 milion Origin of the first primitive reptiles. Further evolution of the reptiles and 215 million 225 mlYlon
strong expansion of the gyrmospermous plants.
t't> o
-
"0 CJCl
,... n � -
Evolution
Evolution
. out 570 �illion years ago, which began ab , d no p N lower � MBRIA '10n of invertebrate animals and . 'T'ho I I IQ CA losive evo I ut xp ste d, eXl n e a hav st of fishes mu broug ht . � the ancestors en wh IS to man S hi es and . algae. T . e be ancestral to all vertebrat wl e IIk uld appeared in the OR which wo roven jawless fishes t Irs e th When e al himself. million years ago, they wer thU S a out 450 nd a , N lu evo IA of DOVIC have had a long period ped and must elo v de y ready full t em tion behind of the ancesto rs of our fishes h at the question s urpn s o n Among re It is . ect of lively discussion. s 'I 11 IS the subj or n, be : h as organism known as � an extremely primitive re the als nim cent a This little creature be oxus (Branchiostoma). or the lancelet the body it has a ta. Throughout the length of A c the to gs n lo . the human vertebral column ICh 'I s comparable with h w ord ch oto n general shape 0f amn as its predecessor. The an can . be see for an ancestor of the what might be expected phioXUS IS a I so
-
The Origin of Life and the Evolution of Fishes
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Stromatolite from the Precambrian of Biwabik, U. S. A. Specimen and photograph: K. G6tz, Munich.
fiSheS' il find. Palaeobranchiostoma . n a recent unique foss. ' There has bee · Af- . mian 0f SOUth been discovered In the. Per has m u erg t 0 t ma ha ' a are h s s . that Acramata and fishe hich leads as to believe r porting evidence are ?ther cho on ancestor. Additional sup ordata. skeleta", especially the Calc/och dates with their "calcareous brates verte the direct ances ?rs of JEFFERIES believes them to be of prevailing. a view which has every prospect
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The question as to when life began on this planet must be almost
_
as old as paleontology itself. It is now supposed that plant life, in
the form of bacteria and unicellular algae, started about 3.5 bil
lion years ago, while animal life, in the form of unicellular flagel
lates, followed at about 1 billion years. This whole period, extend
ing over billions of years, is called the Precambrian. Nobody should
be surprised that fossil remains from this period are rare. Among the oldest are the stromatolites which are important both in the PRECAMBRIAN and in Lower Palaeozoic rocks. They are calcar
eous precipitates built mainly by green-blue algae. Stromatolites are among the most colourful fossils known and give a striking picture of the first organisms inhabiting this planet.
From the latest part of the PRECAMBRIAN a few finds of articu
late animals (annelids, arthropods) are known and some jellyfish,
Branchiostoma, also known as the lancelet or amphioxus. It suggests what the ancestors of fishes were like. (Photograph: Prof. Ax, G6ttingen.)
but they are not very common.
1 8
1 9
Evolution
Evolution
--
omes have been found in Three such cyclost
ys, e Iampre er agnathans still and th at a time when no oth C oniferous, wer arb n is therefore very likely. th� Lo . ionary connectio . An evolut . d --
ans group besides the agnath VONI AN another DE r e ow I), From In the L e the placoderms (PLACODERM These wer . ead spr , re advanced, They was w'Ide , of view they were mo utionary point ol ev e of leading a the ve them the advantag ga ich wh s ile jaw h d mob protected at back and life, Their body was of de mo atory would s�arcely need .to fear armour so that they IJy by powerful a fish-at from our usual picture of y were still far The . s mie ir swim ene be taken for turtles-and the y could even the t sigh NIAN first n limited, In the Upper DEVO may also have bee big ming ability se The g, lon eight metres fearful sizes, up to ld they reached cou so head region and armour confined to the forms had the other placoderms, They siderably quicker than have s wum con but, nevertheless, did ed the seas of the time must have terroriz at the same time as disappeared without issue, not prevail. They , in the Upper DEVONIAN the fossil agathans,
� �
. . . Unnamed chordate from the Lower Carboniferous of Bear Gulch ' Montana , USA Specimen:Adelphi University, Garden City, New Jersey, U.S.A.
appeared in ans (ACANTHODII) had already The puzzling aca nthodi spine) s the nam e indicates (acantho the Upper SILURIAN. As spine, In dal fin carried a powerful all the fins except the cau between s serie ed tinued in a pair some species the spines con , the ures In their external feat the pectoral and the pelvic fins, nisms with an undeniable resem acanthodians were the first orga rtheless, this class is com blance to what we call fishes, Neve ed from the placoderms pletely isolated, It can neither be deriv latter, the acanthodians nor be assigned to the sharks, Unlike the external skeleton, had bony tissue both in the internal and the non-overlapping The body was covered with small, tessellate, branes, These scales some of which extended onto the fin mem of dentine, scales consist of a bony base covered with a layer then died but The acanthodians lasted into the Lower PERMIAN hodians without issue, It is still controversial whether the acant has should be classified in front of the sharks or after them, It are fishes bony even been suggested that the first primi tive =
�
But where do we go from there? It is a long way from such a calcareous chor ate to lan�elet or especially, to a true agnathan,
We problably will never find all the links, though a beginning seems to have been made, The fossil Agnatha diff�r considerably from the organisms that we now recognlz� as fishes, People still argue as to we should
talk of them as fishes, or as fish-like, Their jawless mouth can probably be seen as their essential feature, At best they could , suck or rasp, but never bite, Even their swimming ability may not have been very great, at least for most of them. Some of them reached lengths of 60-80 cm, Probably they lived mostly in fresh I AN and �ater. hey reached their maximum in the Upper S LURI finally disappeared in the Upper DEVONIAN,
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A side branch of the agnat ans, which differs in its anatomy in :nany ways fro� the claSSical representatives but shares the jawless mouth With them, still survives in the form of the hagfishes
20
descended from them,
21
Evolution Perhaps it is not too daring to suppose that primitive. still un known, ancestors of the acanthodians gave rise to all higher fishes. The cartilaginous fishes (CHONDRICHTHYES) appeared considerably later, in the Upper DEVONIAN. As the name implies, they have no true bony tissue. The sharks belo ng to this group as do also the primitive but still surviving chim aeras. The sharks did not reach their maximum until the Upp er Cretaceous, but there are still so many species today that the end of their evolution is by no means in sight. Ossification is ofte n seen as an advanced feature and cho ndif icat ion as a prim itive one. At leas t in this class, however. the opposite is true. The first sharks lived in fresh water and were predators even then. Since the TRIASSIC, however , they have been able to live in the sea. The rays and skates, whic h are related to the sharks, are known first from the Upper Jura ssic, but the beginning of their evolution may be considerably earli er. Up till now, I have discussed three culs-de-sac of evolution and one successful branch road. Now , however, I come to the main route as followed by the bon y fish es (OSTEICHTHYES). The mos t primitive representatives have been found in the Middle DEV O NIAN. but their origins may lie considerably lower. At that time , the skeleton was not complete ly ossified, so at this evolutionary stage they are known as CHO NDROSTEI. The scales were three layered with the outer layer mad e of an enamel-like tissue calle d ganoin. The Lower CARBoNifero us can be seen as the first max i mum of the chondrosteans, but a second maximum followed in the Lower TRIASSIC. After that , they became very uncommon . In the recent fauna their only des cendants are the sturgeons, the the lobe -finn ed pike s and the lobe -finn ed eel Ca/amoichthys ca/abaricus which arose from a side bran ch. rhe next group, which is not truly self-contained, is the "hol os teans" ("HOLOSTEI"). It separated off in the Upper PER MIA N The ir . main common features are an increasing ossification of the inte r nal skeleton and a reduction of the ganoin layer on the scal es. This group reached a maximu m in the Upper JURASSIC and wer e abundant eve n in the CRE TACEOUS. Only in the TERTIAR Y did they lose importance. The only forms still existent are the garpike (Lepisosteus) and the bowfin (Amia).
22
Evolution -
� CRETACE OUS
L..----� JURASS IC
1.-----, TRIASSIC
BONY FISHES (0 STEl C H T HY E S)
D
TERTIARY
-� DO �O �O ffi IX
J:
c(
� mfaD 1= «
0:.
@
CfJ 0:
Li:O � L---�-, �O C!J, � � a: IX 0 PERMIAN
� "-----, CfJ W
CARBONIFEROUS
DEVONIAN
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PY H LOGENIC TREE OF FISHES changed after
BARTHEL
FtnaI/y, in the Upper TRIASSIC, the ancestors should be sought of the true bony fishes (T ELEOSTEI). This is a group of at least 25.000 species and forms the majority of all living fishes. Most of them were small herring-like fishes that still retained a thin layer
23
Evolution
Evolution
of ganoin on the scales, In addition there were somewhat larger fishes, grouped into a total of four orders, which were the only true bony fishes during the whole of the JUR ASSIC and the greater part of the CRET ACEOUS, Then eight new orders were added, while the Lower TERTIARY brought a further nine orders and the Middle TERTI ARY another three, Ali the remaining, rather numerous, orders consist of recent fishes only, Thus about a third of ali true bony fishes have only arisen recently, This sug gests that the evolution of this, the most successful of ali fish groups, is far from exhausted, Which is descended from which can, in many cases, only be guessed, It is not even known with certainty whether we are dealing with a monophyletic or a polyphyletic group, Perhaps
Pholidophorus and Lepto/epis, Finally, however, the Pholidophoriformes may be split they can all be derived from the lineage of
up into several branches and it may not be too outrageous to suppose that other ganoid fishes may also be involved, All the bony fishes so far mentioned are placed in the subclass of the ACTINOPTERYGII, In these all the paired fins are carried by strong rays with a radial arrangement. There are, however, two further fish groups which are separated from them as "flesh-finned" (SARCOPTERYGII), These are the lungfishes (DIPNOI) and the lobe finned fishes (CROSSOPTERYGII), Both of them are known since the Lower DEVONI AN, There is evidence to suggest. however, that they separated off still earlier from the main branch which led to the bony fishes, Both possessed, at that time, the unusual ability to breathe air, Lungfishes reached their maximum in the Upper DEVONIAN and still persist as a few genera today with an enormous geographi cal range including Africa,
Australia and South America, They
can survive droughts embedded in cocoons of mucus, The maximum of the lobe-finned fishes was in the Middle DEVO NI AN, No representative of this group of fishes has ever been found in the Tertiary and they were believed to have died out at
1 938, however, the famous coela Latimeria cha/umnae was discovered, As a living fossil it
the end of the Cretaceous, In canth
showed that the lobe-finned fishes had survived to the present day,
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24
Photo: n of the Comoros Islands, Latimeria at the coastal regio Photograph of a live n, Prof, Fricke,Seewiese
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fresh water, lobe-finned fishes w s in The original habitat of all ho eve , order Coe/aca nthlformes, The representatives of the mer a preferred life in the sea: Latl may from early times have In ded Inclu rs, Among the other orde , itself belongs to this order, h whic e fishes must be sought the higher group Rhipidistia, thos the DEVONIAN, to conquer the already attempted, at the end of of the amphibians and the land and which thus became, by way . all land-dwelling vertebra es, reptiles, the ultimate ancestors of tatives of the lobe-finned Today we know that the last represen the lava cliffs off the fishes pref er to live at grea t dep th in females are up to Comores islands, They are active at night. The still living animals two metres long and viviparous, The number of , tly discovered, is estimated at 250, Thus this living fossil, so recen oros catch is threatened with extinction, The fishermen of the Com d tions a few every year and recently there have even been expe strictest to try to catch living specimens for exhibition, Only the lobe last the tain main and conservation measures may call a halt finned fishes for the future,
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The External Features
of Fish,es
The External Features of Fishes ---
The Fins Fins are very important for fishes since they are the propulsive organs. Because of their very diverse structure they are often used for identification. Basically there are two types of fin-paired and unpair ed, The unpaired fins include the dorsa l fin along the mid line of the back the anal fin situated in the ventral mid line behin d the anus an the caudal fin (tail fin) which forms the posterior end of the fish. The paired fins are the pectoral and pelvic. The pectoral fins are always lateral and just behind the mouth. The pelvic fins, though always located ventrally, vary greatly in positi on. In evolutionary terms the pectoral and pelvic fins correspond to the fore and hind limbs of land vertebrates. It is thought that the first ancestors of fishes had no fins and could move only by undulating their bodies. The predecessors of fins may have been almost undifferentiated stabilization keels. These may have arisen from an uninterrupte d fold of tissue as f?und today in the larval stages of almost all fishes. Perhaps at , , first ridge s of cartila ge devel oped in these folds which later divided into a basa l portion, transverse to the body, and a radial portio n ex endin g perpendicularly into the tissue fold. In any . cas�, thiS IS the type of fin still found in living agnathans, both agfl� es and lampreys. Since these repre sent the most primi tive living fishes, the median fins may have arisen in this manner. The origin of the paired fins cannot be imagi ned so easily. Per haps a fold running on left and right from the gill openings to the �nal region may have played a role corresponding to the median fin fold. As yet, however, such a paired fold has been found only in the fossil agnathan Jamoytius. In the sharks the supporting rays are further subdivided al thoug this cannot be seen from outside since they are co ered by skin and muscle. The still-living sturg eon also has fins of primitive type, In these fishes the dorsa l and anal fins have a muscular lobe at the base which surrounds rod-like structures in the body and rays in the externally visibl e parts of the lobes. Such fins are similar to typical shark fins but, unlike them, the outer part of the fin is supported by bony rays-the so-called
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of the fin .I h' Higher fishes lack this lobe at the base LeP.I have body, otriChj a, attached to little nodes in the . e and ort for the external part of the fin. only . supp beCome the rt'lng skeleton of the caudal fin is different, for modifi Ttle supp o column are 'InvoIved . the Posterior part of the vertebral . cations 0f I and the fin runs around 't rtebral column remains straight If l the fin, cauda cal otocer pr a of fringe, we speak of Ifas extends into a longer upper lobe, ds upward and . column ben remains shorter, then we have a heterocerca I ile the lower lobe sharks and chondrosteans. fin. This type is found among all ar s The opposite case, when the vertebral column bends downw and runs into the lower lobe, is called a hy�ocerc�1 caudal fin. occurs in the agnathans and also In the Ichthyosaurs.
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e sa e of com e are not fishes but I mention them for t rically Into e�ual ness.) If the caudal fin is divided symmet . is undivided, then the fin I� sized upper and lower lobes, or looks absolutely sy�m� rI homocercal. Externally this type of fin the more primitive cal but anatomy shows that here also, in end . This strongly fonns, the vertebral column turns upward at. the . from the evolution In arose fin cal indicates that the homocer t bony fo mos typical heterocercal fin.· The homocercal fin is . . � fishes. Finally there is the diphycercal caudal fin In which the vertebral column remains straight and the caudal fin is divided into two equal lobes, Perhaps this is the most primitive type of caudal fin. It is found in some of the lobe-finned fishes.
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In general the caudal fin, like the dorsal and anal fin, is made up of simple rays and jointed rays which serve to support a thin membrane. Spines are never present. Finally, for completeness, I mention a type of fin which o� IY in the headfish Mala. This is the gephyrocercal caudal fin.
occurs
It terminates the body by running as a fringe between the dorsal and anal fins.
27
The External Features
of Fishe,s
The External Features
Types of Caudal Fins
scales
of Fishes
an d Sp in es
s is fundamentally like that of other vertebrates, It t of fishe The �k'n a thicker layer of a very thin outer layer (epidermis) and consls p u several layers of of made is is epiderm The n th (dermis) . ally worn away by continu being layers ost t>,et P cells the outerm Sim other hand , is the dermis on , The , me ns and replaced na u.ral . . a In IC t' h h' t w Issue muscI e e layer of connectiv 1 rrned of a thick . fine mucus which n erves and b lood vessels extend The a fish and makes it slippery is secreted by special gland in the ep ide rm is. . have another body covering I .e. In addition to the skin, most fishes to as an exoskeleton . In referred sometimes are which the scales, ned in some way. strengthe always is skin the scaleless fishes it remains soft scales, for however, substrate a When it serves as and also relatively thin. Sharks and rays have dermal denticles which are also known as placoid scales. Each of these has a bone-like base embedded in the skin which at the surface bears a spine pointing backwards and covered with enamel . The rudiments of these denticles arise already in the skin of the embryo. Placoid scales, unlike the scales of bony fishes, do not enlarge as the fish grows. Rather do new placoid scales insert themselves between those already there, so that the growing body always remains covered . The shape of the dannal denticles varies with the genus and ranges from spine-like to wart-like. Some rays have even completely lost their denticles and retain only a smooth skin. Stingrays have a tail spine instead of the dorsal fi n . This spine can be cast off if necessary and replaced by a new one. The chi maeras and their relatives (Holo cephali ) have largely a naked skin but there are places with little denticles almost like those of sharks . In bony fishes the scales arise from the dermis. I start by describ ing cosmoid scales which are found in many lobe-finned fishes and fossil lungfishes . The individual scale is here made of four layers. The innermost layer consists of dense bone . Above this is a of porous bone, then a dentine-like cos mine layer and finally a thin superficial layer of enam el . � chondrosteans have evolved another type of scale-the ga noid scale. In these the dentine layer is thinner and the bony layer correspondingly thicker. The most striking feature of this type of ' leaIe, however, is the thick layer of enamel which is referred to as
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hypocercal triphycercal
Shapes of C audal Fins
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29
The External Features of Fishes the ganoine layer. These layers are deposited concentrically around a tiny cosmoid scale . It is supposed that ganoid scales evolved earlier than cosmoid scales and that the l atter originated by a reduction of the thick ganoin layer. Among still living fishes the primitive type of scale is found only in paddlefishes and in the African bichir and its relatives. In the "holosteans" a reduced type of ganoid scale occurs. It consists of only two layers and of these the enamel-like ganoine layer h as become appreciably thinner. Such scales are found today only in the garpike Lepisosteus and are sometimes therefore referred to as the "Iepisostoid" type of scale. Most ganoid scales are rhomboidal in outline. AU "ganoid' fishes were thus enclosed in a thick, rather inflexible armour whIch must have made them relatively immobile. On the other hand such scales offered a more or less effective defence against predators. Such fishes were therefore not adapted for rapid swimming and even the predators among them may have c