Produced by Tom Cosmas compiled from images made available
by The Internet Archive.
Transcriber Note
Text emphasis denoted as _Italics_ and =Bold=. Whole and fractional
parts of numbers as 123-4/5.
THE COAL MEASURES AMPHIBIA
OF
NORTH AMERICA
By
ROY LEE MOODIE
_Associate in Anatomy, University of Illinois, Chicago_
[Illustration]
Published by the Carnegie Institution of Washington
WASHINGTON, 1916
CARNEGIE INSTITUTION OF WASHINGTON
Publication No. 238
PRESS OF J. B. LIPPINCOTT COMPANY
PHILADELPHIA
PREFATORY NOTE.
The Carnegie Institution of Washington has already published several
monographs upon paleobiological subjects, written by its research
associates, Hay, Wieland, and Case. Each author has dealt with the
subject-matter of his particular field, but each has brought to bear upon
his work common factors which have placed his labors upon a broader basis
than the mere morphological descriptions of fossil forms of life. Case
has published four monographs upon the morphology and taxonomy of the
Permo-Carboniferous vertebrates of North America, and has followed these
by a fifth, in which all the known factors bearing upon the development of
the life were assembled in an effort to discuss the paleogeography of the
period. In his conception paleogeography is a very broad term, involving
not only a study of the distribution of land, water, and life in any one
interval of time, but a consideration of all the factors in the extremely
complex inter-relations of organic and inorganic matter and causes which
influence the development of each part.
Geologists and paleobiologists have alike suffered in their interpretation
of past conditions, because of their lack of knowledge of the work
done by others. Stratigraphy may not be interpreted from the preserved
fossils without a knowledge of biological laws, and the formations of the
earth may not safely be rearranged to account for the present or past
distribution of life without a knowledge of geological processes.
It is obvious that such work is beyond the possibilities of any one man;
it is rather the work of a group of men, each broadly trained and each
master of his own field and able to contribute to and criticize the
work of his fellows. Nowhere could close cooperation of this kind be
better accomplished than under a system such as the Carnegie Institution
of Washington has developed, whereby the research associates of the
Institution and others of its staff may call in the assistance of men in
related fields. Already the value of this procedure is apparent in the
results accomplished by cooperation.
The following monograph, by Dr. Roy L. Moodie, adds an important link
to the series of paleobiological publications of the Institution and is
closely connected with the work already done upon the Permo-Carboniferous
vertebrates, since it supplies a description of the life of the period
immediately preceding. It is hoped that the volume will contribute
in no small measure to an understanding of the broader problems of
paleogeography and the recognition of the mutual problems of the
paleobiologists and the geologists.
E. C. Case.
University of Michigan, _March 15, 1916_.
PREFACE.
The question of the origin of land vertebrates, which has appealed so
strongly to students of fossil Amphibia, is by no means solved from the
material furnished by the Coal Measures of North America. The Amphibia
are, however, well known from several localities in the Coal Measures of
this continent, where skeletons have been recovered which are sufficiently
well preserved to afford a fair knowledge of their anatomy. The specimens
rescued from the dumps of the old mines are regrettably few in comparison
with the number that must have been burned as fuel, or carried down the
slopes as silt. Yet scanty as is the material thus collected, it is of
great importance, because it represents such an early period in the
recorded history of the air-breathing vertebrates.
The amphibian fauna in the Coal Measures of North America is represented
by several hundred individual specimens, preserved in various museums. All
of the collections have been available in the preparation of this memoir,
with the exception of those species from Nova Scotia which are preserved
in the Peter Redpath Museum of McGill University and in the British
Museum of Natural History. The European material, which has been used in
comparisons with the American forms, has been studied chiefly from the
literature, although there have been available a series of specimens of
_Branchiosaurus amblystomus_ Credner, from Saxony, presented by the late
Professor Credner, and a single specimen of _Archegosaurus_ from Dr. von
Huene, of Tübingen.
The collection which has been of the greatest value is that at the
American Museum of Natural History, chiefly assembled by Dr. J. S.
Newberry from the dumps of the coal mines at Linton, Ohio, while he was
in charge of the Ohio Geological Survey (1869-1884). This collection, a
part of which is at Columbia University, furnished Cope with the most of
his type material for the "Synopsis of the Extinct Batrachia from the Coal
Measures" (123).[A] This entire collection, including all of Professor
Cope's types and representing many new and hitherto undescribed forms,
was generously placed at the writer's disposal for a period of five years
through the kindness of Dr. Bashford Dean and Dr. Louis Hussakof. Dr.
Hussakof made a trip through the Linton region and his description of the
place occupied by the "Old Diamond Mine" is given on page 16.
[Footnote A: The numbers in parentheses refer to the bibliography at the
end of this volume.]
An interesting collection of air-breathing vertebrates from the Coal
Measures, representing 19 species, is in the U. S. National Museum (464).
This is chiefly the collection of Mr. R. D. Lacoe and includes specimens
from Mazon Creek, Illinois, from Kansas, and from Linton, Ohio. It is
especially important in that it contains the skeleton (plate 20, fig. 3)
of _the oldest known reptile_, _Eosaurus copei_ Williston (Jour. Geol.,
XVI, 295). It contains also, besides many of Cope's types, new forms which
have been described by the writer (464, 470, 471, 472, 473, 474, 478,
479). Dr. Stuart Weller first secured the use of this collection for me,
and its continued use has been granted by Dr. C. D. Walcott. Mr. Charles
Gilmore has called my attention to several interesting specimens and has
kindly loaned them for description.
A small but interesting collection of Mazon Creek Amphibia is that of the
Peabody Museum of Yale University. Through the courtesy of the officers
of this museum the writer was permitted to study these specimens and
was given a grant for their illustration. The results of that study
are contained in a previous paper (478) and in the present memoir. Dr.
Schuchert has offered suggestions as to the environmental conditions of
the ancient Amphibia.
A few specimens of Coal Measures Amphibia are at the Walker Museum,
University of Chicago. This collection includes the type of _Micrerpeton
caudatum_ Moodie, the first branchiosaur discovered in the western
hemisphere, and a few specimens from Linton, Ohio.
A single specimen of _Amphibamus grandiceps_ Cope, very beautifully
preserved, is in the possession of Mr. L. E. Daniels, of Rolling Prairie,
Indiana. This specimen has been studied and described by Hay (316) and by
the writer (462, 469, 478).
The works of Cope and Dawson, published between 1860 and 1897, on the
Amphibia from the Coal Measures, have been indispensable in the present
study. It has been necessary to rely on the published descriptions and
photographs of the interesting fauna from Nova Scotia, since it has not
been possible for me to visit and examine the types preserved in the Peter
Redpath Museum of McGill University and in the British Museum of Natural
History. It has been possible to check Dawson's work, to a certain extent,
by a study of a series of excellent photographs of the types of Coal
Measures Amphibia collected by Dawson and Lyell and described by Dawson
and Owen. The descriptions of these authors have been drawn on for the
discussion of the Canadian forms.
The descriptions given below have been made full and complete in the
belief that in this way our knowledge of these interesting vertebrates
may be advanced. Many of the species have been described elsewhere in
scattered papers by various authors. These descriptions have been revised
and verified and are collected here in monographic form. The work is a
morphologic and taxonomic revision of the Amphibia from the Coal Measures
of North America. Especial attention has been paid to the factors which
have been most active in the evolution of the group, so far as these
factors may be interpreted. It is the author's hope that this review may
open up the field for many more workers, since we are just beginning to
learn about the evolution of this group of vertebrates.
The trustees of the Elizabeth Thompson Science Fund allotted a grant for
the present investigation. This aid has enabled the writer to present his
work in much better form than would have been possible otherwise. Dr.
S. W. Williston has offered many suggestions and criticisms which have
been gratefully adopted. It is with the greatest sense of pleasure that
the author dedicates this memoir to his teacher and friend. After the
manuscript was completed the author enjoyed a visit from Mr. D. M. S.
Watson, of King's College, London, whose knowledge of the European and
African forms enabled him to offer several very valuable suggestions.
It is fitting also to express my indebtedness to the Carnegie Institution
of Washington for the privilege of publishing my work in the series of
monographs contributed by Dr. E. C. Case, dealing with the anatomy and
relationships of the early land vertebrates of North America.
Roy Lee Moodie.
CONTENTS.
PAGE.
Prefatory Note iii
Preface vi
List of Illustrations viii-x
CHAP.
I. The Problem of the Amphibia from the Coal Measures 3-5
II. History of the Discovery of Amphibia in the Coal Measures 6-8
III. Stratigraphic and Geographic Distribution of Amphibia in
the Coal Measures of North America 9-22
IV. The Morphology of the Coal Measures Amphibia 23-36
V. The Amphibia of the Devonian and Mississippian of North
America 37-38
VI. A History of the Classification of the Amphibia, With
Especial Reference to the Species from the Coal Measures 39-45
VII. Classification of Amphibia Adopted in This Work, and a List
of the Coal Measures Amphibia from North America 46-48
VIII. Definition of the Class Amphibia, the Subclass Euamphibia,
and the Order Branchiosauria 49-50
IX. The American Coal Measures Branchiosauridæ 51-66
X. The Order Caudata 67-71
XI. The Order Salientia 72-74
XII. The Subclass Lepospondylia, the Order Microsauria, and
the Group Aistopoda 75-77
XIII. The Microsaurian Family Hylonomidæ, from the Coal Measures
of Nova Scotia 78-84
XIV. The Microsaurian Family Tuditanidæ, from the Coal Measures
of Ohio and Pennsylvania 85-111
XV. The Microsaurian Family Stegopidæ, from the Coal Measures
of Ohio 112-114
XVI. The Microsaurian Family Urocordylidæ, from the Coal
Measures of Nova Scotia 115-125
XVII. The Microsaurian Family Amphibamidæ, from the Coal Measures
of Mazon Creek, Illinois 136-134
XVIII. The Microsaurian Family Nyraniidæ, from the Coal Measures
of Ohio 135-138
XIX. The Aistopodous Microsaurian Family Ptyoniidæ, from the
Coal Measures of Ohio 139-146
XX. The Microsaurian Family Molgophidæ, from the Coal Measures
of Ohio and Mazon Creek, Illinois 147-154
XXI. The Microsaurian Family Sauropleuridæ, from the Coal
Measures of Ohio 155-170
XXII. The Microsaurian Family Ichthycanthidæ, from the Coal
Measures of Ohio 171-174
XXIII. Supposed Microsaurian Species of Uncertain Relationship 175-177
XXIV. The Temnospondylous Amphibia from the Coal Measures of
North America 178-197
XXV. The Stereospondylous Amphibia from the Coal Measures of
North America 198-201
Bibliography of the Fossil Amphibia, With Especial
Reference to the Amphibia from the Coal Measures of
North America 202-217
An Index to the Bibliography of Fossil Amphibia 218-219
Index 220-222
ILLUSTRATIONS.
PLATES.
PAGE.
1. Views along Mazon Creek, Illinois 12
2. Drawing of type specimen of Micrerpeton caudatum Moodie, from
the Coal Measures of Mazon Creek 52
3. Specimens of Eumicrerpeton parvum, Erpetobrachium mazonensis,
Erierpeton branchialis, Mazonerpeton longicaudatum, and
Amphibamus grandiceps 58
4. (1 and 2) Vertebræ of Spondylerpeton spinatum Moodie.
(3) Type specimen of Mazonerpeton costatum Moodie.
(4) Type skeleton of Cephalerpeton ventriarmatum Moodie.
(5 and 6) The halves of the nodule containing a practically
complete skeleton of Amphibamus grandiceps Cope 60
5. (1) A reconstruction of the Coal Measures branchiosaurian,
Eumicrerpeton parvum Moodie, a small primitive salamander 64
(2) A restoration of the branchiosaurian, Mazonerpeton, based on
two specimens 64
6. Dendrerpeton acadianum Owen. Mandibles, parts of anterior
extremities, humerus, etc. 68
7. Hylerpeton dawsoni Owen. Mandible, teeth, rib, and bones of
anterior extremity. Bones of pelvis and posterior limb and
bony scales 72
8. Fritschia curtidentata Dawson. Bones of skull and anterior
extremity, bony rods of belly, of pelvis, and posterior
extremity 76
9. Hylonomus lyelli Dawson. (1) maxillæ and skull bones;
(1_a_) sternal bones; (2) mandible; (3) humerus, ribs,
and vertebræ; (4) posterior limb; (5) pelvis; (6) caudal
vertebræ 78
10. Hylonomus latidens Dawson. Skull, portion of skeleton, foot,
scapular, and sternal bones, humerus and rib, believed to
belong to this species. Erect tree, Coal formation, of Nova
Scotia 80
11. Hylerpeton longidentatum Dawson. Mandible and other bones. Erect
tree, Coal formation 82
12. Smilerpeton aciedentatum Dawson. Mandible, portions of skull,
scales, and various bones. Erect tree, Coal formation 82
13. Dendrerpeton oweni Dawson. Skull, mandible, and bones of
anterior limbs, posterior limb, pelvic, and bony scales 100
14. (1 and 2) Amphibamus grandiceps Cope, from the Mazon Creek shales 106
(3) Sauropleura (Colosteus) scutellata Newberry, from the Linton
Coal Measures, the first known of the Ohio Coal Measures
Amphibia; at first ascribed by Newberry to the fishes, but
later correctly identified by Cope 106
(4) Type of Diceratosaurus (Ceraterpeton) punctolineatus Cope,
from the Linton Coal Measures 106
15. (1) Dorsum of skull of Diceratosaurus punctolineatus (Cope),
from the Coal Measures of Linton, Ohio 114
(2) Ventral surface of skull of Diceratosaurus punctolineatus
(Cope), from the Coal Measures of Linton 114
(3) Pectoral girdle of Diceratosaurus punctolineatus (Cope),
from the Coal Measures of Linton 114
(4) Cervical or anterior dorsal vertebra of Diceratosaurus
punctolineatus (Cope), from the Linton Coal Measures 114
16. (1) Type specimen of Diceratosaurus punctolineatus Cope 116
(2) Skull of Sauropleura longidentata Moodie, from the Coal
Measures of Linton, Ohio 116
(3) Mandible of Sauropleura longidentata Moodie, from the Coal
Measures of Linton, Ohio 116
(4) Type specimen of Sauropleura enchodus Cope, from the Coal
Measures of Linton, Ohio 116
(5) Additional specimen of Diceratosaurus punctolineatus Cope,
from the Coal Measures of Linton, Ohio 116
17. Type of Saurerpeton latithorax Cope 126
18. (1) Type of Erpetosaurus sculptilis Moodie, from the Cannelton
Shales of Pennsylvania 132
(2) Skeletal elements of Eryops sp. indet., from the Pittsburgh
Red Shale at Pitcairn 132
(3) Amphibian footprints, Dromopus aduncus Branson, from the
Mississippian shales of Giles County, Virginia 132
(4) Type of Thinopus antiquus Marsh, amphibian footprint from
the Devonian of Pennsylvania 132
19. Type of Ctenerpeton alveolatum Cope, from the Coal Measures
of Ohio 134
20. (1) Skull of Erpetosaurus minutus Moodie, from the Cannelton
slates of Pennsylvania 154
(2) Skull and anterior part of body of Ptyonius pectinatus Cope,
from the Coal Measures of Linton 134
(3) Skeleton of Eosauravus copei Williston, from the Coal
Measures of Linton. "The oldest known reptile from
North America" and closely related structurally to the
Microsauria 134
(4) Part of ventral scutellation and ribs of Sauropleura digitata
Cope, from the Coal Measures of Linton 134
21. (1) Mandible of Macrerpeton deani Moodie, from the Linton Coal
Measures 136
(2) Portion of the skull of Macrerpeton deani Moodie, possibly
of the same: individual us the mandible. From the Linton
Coal Measures 136
(3) Type of Cercariomorphus parvisquamis Cope, from the Linton
Coal Measures 136
(4) An additional specimen of Cercariomorphus parvisquamis Cope,
from the Linton Coal Measures 136
(5) Skull of Sauropleura scutellata Newberry. From the Coal
Measures of Ohio 136
(6) Tooth of Mastodonsaurus sp. indet. of the Carboniferous of
Kansas 136
(7) Tooth of Mastodonsaurus giganteus Jaeger, from the Triassic
of Germany. Introduced for comparison with the tooth from
the Kansas Carboniferous 136
22. (1) Type of Leptophractus lineolatus Cope, from the Coal Measures
of Linton. Portions of maxilla and mandible of left side
with teeth 160
(2) Type of Proterpeton gurleyi Moodie, from the Coal Measures
of Illinois, near Danville. Cervical of an otherwise
unknown amphibian 160
(3) Amphibian phalanx from the Coal Measures near Breeze,
Illinois, of an unknown species 160
(4) Large rib of a stereospondylous stegocephalan, otherwise
unknown 160
(5) Type of Cope's species Tuditanus mordax referred by him to
the cranium, on account of the sculpturing of the elements,
now known to be portions of the interclavicle and clavicles
of Diceratosaurus punctolineatus 160
(6) Skull of Baphetes planiceps Owen, from the Coal Measures of
Nova Scotia 160
23. (1) Ventral scutellæ of Ctenerpeton alveolatum Cope, from the
Coal Measures of Ohio 166
(2) Left leg and pelvis of Ichthycanthus platypus Cope, from the
Coal Measures of Ohio 166
24. (1) Type specimen of Pelion lyelli Wyman, from the Coal Measures
of Ohio. Supposed to represent the ancestral form of the
Salientia 172
(2) Scales of Cercariomorphus parvisquamis Cope, a microsaur
from the Ohio Coal Measures 172
(3) Type specimen of Cercariomorphus parvisquamis Cope 172
25. (1) Photograph of type specimen of Erpetosaurus (Tuditanus)
radiatus Cope, from the Coal Measures of Linton 180
(2) Photograph of type specimen of Erpetosaurus tabulatus Cope,
from the Coal Measures of Linton 180
(3) Photograph of the impression of Stegops divaricata Cope,
from the Coal Measures of Linton 180
(4) Type and only known specimen of Micrerpeton caudatum Moodie,
a branchiosaur from the Coal Measures shales of Mazon Creek 180
26. (1) Type specimen of Erpetosaurus tuberculatus Moodie, from the
Ohio Coal Measures 182
(2) Type of Macrerpeton huxleyi Cope, from the Coal Measures
of Ohio 182
TEXT-FIGURES.
1. Map of the Coal Measures in North America 9
2. Distribution of Coal Measures Amphibia in North America 11
3. Topographical Map of Mazon Creek Region 13
4. Topographical Map of Linton, Ohio, Region 16
5. Fossil Tree Trunk in Position 21
6. Generalized Amphibian Skull 23
7. Alimentary Canal of a Carboniferous Salamander 26
8. Vertebræ and Ribs of Coal Measures Amphibia 28
9. Ventral Scutellæ of Micrerpeton 30
10. Horny Armor of Hylonomus 31
11. The Skulls of two Microsaurians: A, Eoserpeton tenuicorne;
B, Ceraterpeton galvani 33
12. Devonian Footprint 37
13. Restoration of Micrerpeton 53
14. Mazon Creek Amphibia: A, Eumicrerpeton parvum;
B, Amphibamus thoracatus 59
14_a_. Skeleton of Mazonerpeton longicaudatum 62
14_b_. Skeleton of Mazonerpeton costatum 64
15. A. Impression of Erierpeton branchialis 65
B. Eumicrerpeton parvum 65
C. Larger Specimen of Eumicrerpeton parvum 65
D. Skeleton of Erpetobrachium mazonensis 65
E. Rib of Mazonerpeton costatum 65
15_a_. Type Material of Sparodus 66
16. Obverse of Cocytinus gyrinoides 68
16_a_. Nearly Complete Specimen of Cocytinus gyrinoides 69
17. Pelion lyelli, supposed ancestral Salientian 74
18. Skeletal Elements of Smilerpeton aciedentatum 82
19. Skull and Skeleton of Tuditanus punctulatus 87
20. Skull and Skeleton of Tuditanus longipes 90
21. Skeleton of Tuditanus walcotti: A, Body; B, Leg 94
22. A. Outline of Skull and Cranial Elements of Erpelosaurus minutus
Moodie, from the Cannelton Slates of Pennsylvania 99
B. Outline of Skull and Cranial Elements of Erpetosaurus radiatus
Cope, from the Coal Measures of Linton 99
C. Palate of Erpetosaurus (tabulatus?), from the Coal Measures of
Linton, Ohio 99
D. Outline of Skull and Cranial Elements of Erpetosaurus
acutirostris Moodie, from the Coal Measures of Linton, Ohio 99
E. Outline of Larger Part of Skeleton of Odonterpeton triangularis
Moodie, from the Coal Measures of Linton, Ohio 99
F. Right Mandible of Erpetosaurus tabulatus Cope, from the Linton,
Ohio, Coal Measures 99
G. Skull Elements and Lateral-line Canals of Erpetosaurus
tabulatus Cope, from the Coal Measures of Linton 99
23. Skull of Stegops divaricata 113
24. Microsaurian Skulls from Linton, Ohio: A, Diceratosaurus lævis;
B, Diceratosaurus robustus 119
25. Restoration of Eoserpeton 124
26. Restoration of Amphibamus 128
27. Skeleton of Amphibamus grandiceps 129
28. Probable Appearance of Amphibamus 130
29. Skeleton of Cephalerpeton 133
30. Restoration of Ptyonius 140
31. Restoration of Œstocephalus 144
32. Vertebræ of Molgophis brevicostatus 148
33. Fore-limb of a Member of the Molgophidæ, Possibly Pleuroptyx 152
34. A. Interclavicle of Sauropleura pauciradiata 159
B. Left Clavicle of Sauropleura pauciradiata 159
35. Skull and Skeleton of Saurerpeton latithorax 164
36. Mandible of Leptophractus dentatus 169
37. So-called Interclavicle of Eurythorax sublævis 170
38. Skeletal Elements of Amblyodon 177
39. Vertebra of Spondylerpeton spinatum 179
40. Mandible of Macrerpeton deani 184
41. Vertebræ of Eosaurus acadianus: A, Oblique Lateral View;
U, Oblique View; C, Posterior View; D, Transverse
Section; E and F, Microscopic Sections 188
42. Skull and Mandible of Eobaphetes kansensis: A, Outer View of
Mandible; B, Portion of Skull; C, Inner Surface of Mandible 191
43. Footprints of Dromopus agilis 200
===============================
THE COAL MEASURES AMPHIBIA
OF NORTH AMERICA
===============================
CHAPTER I.
THE PROBLEM OF THE AMPHIBIA FROM THE COAL MEASURES.
The Amphibia from the Coal Measures of North America present the
problem of the origin of the land vertebrates, since the air-breathing
vertebrates in the Coal Measures of this continent are the earliest
known in the western hemisphere. The difference in age between the
chief amphibian-bearing deposits of North America and Europe is not
great, although it has been asserted that _Pholidogaster_ and its
allied fauna, described by Huxley from Scotland (331), is much older,
probably Mississippian. It is interesting to note that these earliest
representatives of the Amphibia in Scotland are all temnospondyles, of
which there are very few representatives in the Coal Measures of North
America.
The forms so far described from the North American Coal Measures present
a very high degree of development and differentiation, the earliest known
species being already specialized and well adapted for various modes of
life. As far back in geological time as the middle Coal Measures, when
the first well-defined forms are known, environmental conditions had
effected a wide diversity of structure within the group. Thus, early in
the geological history of the land vertebrates, we have, among the Coal
Measures Amphibia, various forms which had specialized into strictly
aquatic, terrestrial, subterrestrial, and arboreal, or at least partly
arboreal. Specialization had extended to the loss of limbs, ribs, and
ventral armature in a few species, and to the acquirement of claws,
running legs, or a long propelling tail with expanded neural and hæmal
arches in others. The forms range in size from small creatures less than
an inch in length to large species which must have attained a length of
several feet. A rather interesting parallel, though of no phylogenetic
significance, can be drawn between the Amphibia of the North American
Coal Measures and the reptiles of to-day. The snakes are represented by
the limbless, snake-like forms, such as _Ptyonius_ and _Phlegethontia_.
The lizards find their counterpart in the Hylonomidæ and the Tuditanidæ.
No known characters of these animals tend to ally them directly with any
known group of fishes, except in the most general way. These facts all
indicate a long antecedent history for the amphibian group or else a
preceding period of greatly accelerated development of which we now know
nothing.
The Amphibia whose remains have been brought to light from the Coal
Measures have hitherto been regarded as pertaining to a single order, the
Stegocephalia, characterized by the completely roofed-over cranium and a
large parasphenoid. The writer (469) had previously assigned 5 suborders
to the group: the Branchiosauria, Microsauria, Aistopoda, Temnospondylia,
and Stereospondylia. All of these groups are represented in the Coal
Measures of North America. It has seemed inadvisable, in the light of our
present knowledge of the Amphibia, to retain these 5 groups as suborders,
and, in the revised scheme of classification which has been published
elsewhere (469), they are given the rank of orders all excepting the
Aistopoda, which are now regarded by the writer as specialized Microsauria.
The recent Caudata are possibly represented in the North American Coal
Measures by forms which may be assigned tentatively to the Proteida.
Such forms as _Cocytinus gyrinoides_, _Hyphasma lævis_, and _Erierpeton
branchialis_ possibly represent this group in the Pennsylvanian. This
relationship is based chiefly on the structure of the hyobranchial
apparatus and on the general structure of the species. The three
above-mentioned species are, however, very insufficiently known, and
the relationship can hardly be regarded as more than suggested by the
characters which are at hand.
The Salientia, or frogs, may possibly have their ancestral type in _Pelion
lyelli_, the first known species from the Linton, Ohio, Coal Measures.
Oddly enough, among the hundreds of specimens collected later from this
horizon, not a fragment can be identified with this species. The type
specimen is unique, and although incomplete its characters are suggestive.
The Branchiosauria are represented in North America by four species:
_Micrerpeton caudatum_, _Eumicrerpeton parvum_, _Mazonerpeton
longicaudatum_, and _M. costatum_. Three other genera which occur in North
America have been placed (642) in this group, but they do not belong
there, for reasons given below. The branchiosaurs were salamander-like
in appearance. They were naked, with the exception of small ovoid scales
on the back and the chevron-shaped armature of the ventral surface, the
latter being almost universally present among the Paleozoic Amphibia. They
were adapted for life in the water for at least the early part of their
existence, as is shown by the possession of gills on many of the late
Carboniferous and early Permian forms of Europe. The group is, without
doubt, ancestral to the modern Caudata. No branchiosaurians have been
described elsewhere from so low in the geological series as those here
given and they are the first and only evidence of the occurrence of the
group in the western hemisphere.
The Microsauria are represented in the Coal Measures by numerous
forms which are usually characterized as lizard-like animals with a
well-developed ventral scutellation. Other characters, such as the
possession of lateral-line grooves on the cranium, the arrangement of the
cranial elements, and the condition of the ribs, will be discussed further
on. The pectoral arch is well developed and is composed of five dermal
bones plus the regular skeletal elements. The skeletal membrane bones are
sculptured after the manner of those of the cranium. The bodies of the
animals were, in a few cases, covered with scales; but most of them appear
to have been completely naked, even the ventral armature being absent in
some cases. The ventral scutellation was especially strong and highly
developed in some of the forms; _e.g._, in the genera _Saurerpeton_ and
_Sauropleura_. The vertebræ are uniformly of the hour-glass or notochordal
type. This is so generally the case that the characters of the vertebræ
and ribs are taken as the chief diagnostic characters of the major
groups. Various peculiarities are seen among the Microsauria, such as the
development of horns in various genera which are, apparently, related.
The order seems to have gone completely out of existence during the early
Permian, and if their descendants continued on as reptiles, as has been
suggested (469), we do not know the intermediate stages.
The Aistopoda are without doubt specialized microsaurs, and, in the
opinion of the writer, are not entitled to separate rank. Some of these
forms reached a high degree of specialization. One American species has
the skeleton reduced to a long, slender head and a slender series of
elongate vertebræ, all other parts of the skeleton, even the ventral
armature, being absent. The proportions attained by this species,
_Phlegethontia linearis_ Cope, recall those of the coach-whip snake,
_Zamenis flagellum_ Shaw, of the western plains. Some of the so-called
Aistopoda have been credited by Fritsch with the possession of peculiar
clasping organs, "Kammplatten." Newberry has written of the discovery of
similar structures in the Ohio Coal Measures (498), but the statement of
the actual association of these "Kammplatten" needs confirmation. Dr. R.
H. Traquair wrote to the author under date of April 28, 1909:
"I maintain that the association of a bundle of 'Kammplatten' with
a specimen of _Ophiderpeton_ in the Bohemian gas coal was entirely
_accidental_. Of such pitfalls the paleontologist has to beware or serious
mistakes may be the consequence, as has happened more than once. I must,
however, publish a short paper on the Kammplatten, for I think I know what
they are now."
Fritsch, however, has very clearly figured a nearly complete specimen
of _Ophiderpeton_ (251, Bd. IV) as possessing the Kammplatten in place
near the cloaca, where he suggests they may have served the function of
accessory copulatory organs or claspers.
The Temnospondylia are represented by scanty remains of species from
Illinois, Pennsylvania, and Nova Scotia. The forms belonging to this group
are all relatively large, and they had a wide geographical distribution
during the Permian. This group contains two types of vertebræ, known
as the embolomerous and the rachitomous, both of which are present in
the Coal Measures. Such forms as _Eosaurus_, _Baphetes_, _Eobaphetes
kansensis_, _Macrerpeton_, and _Dendrerpeton_ are regarded tentatively as
temnospondyles, but there is no definite assurance that they are such.
It is possible that _Eosaurus_ is a stereospondyle, but the species is
too incompletely known for a definite statement to be made. The close
resemblance between the vertebræ of _Eosaurus_ and _Anthracosaurus_ has
been noted by Huxley (332).
The Stereospondylia are very scantily represented in the Coal Measures,
if at all. _Eosaurus_ may belong here as indicated above. The tooth and
cranial fragments discovered and described by Williston from the Coal
Measures of Kansas may represent a stereospondyle as he states (608),
but the evidence is incomplete. A fragment of a large rib (plate 22,
fig. 4) of a species from Linton, Ohio, otherwise unknown, may be a
stereospondyle. We would expect an early development for this group,
but it is' an interesting fact that no stereospondyles are known
definitely before the Triassic, during which period they had an extensive
distribution.
CHAPTER II.
HISTORY OF THE DISCOVERY OF AMPHIBIA IN THE COAL MEASURES.
Sir William Logan, in 1841, discovered in the Coal Measures of Horton's
Bluff, Nova Scotia, some tracks of Amphibia which he carried to London
and which Sir Richard Owen pronounced to be undoubted "reptilian" tracks.
This fact was published in 1842 (380) and was the first recorded evidence
of the occurrence of land vertebrates in the Carboniferous rocks of the
world. To these tracks Sir William Dawson later gave the name of _Hylopus
logani_.
Two years later Dr. Gergens (291) wrote a letter to Professor Bronn, the
founder and one of the editors of the "Neues Jahrbuch für Mineralogie,
Geologic und Paleontologie," in regard to an important discovery in the
Carboniferous rocks of Germany. The letter is of such exceptional interest
in connection with the history of the fossil Amphibia that it is given
here:
"In dem Brandschiefer von Münsterappel in Rhein-Bayern habe ich in
vorigen Jahre einen Salamander aufgefunden und Hrn. H. v. Meyer in
Frankfurt zur näheren Untersuchung und Beschreibung übergeben;--Gehört
dieser Schiefer der Kohlen-Formation?--in diesem Falle ware der Fund
in anderen Hinsicht interessant."
The form discovered by Dr. Gergens and described by Hermann von Meyer as
an amphibian is a little puzzling as to its characters. Miall (449, p.
183) says that the remains are too imperfect for close definition. The
form, as figured, resembles an immature branchiosaurian, as one is at once
reminded, from an examination of Von Ammon's _Branchiosaurus caducus_ (7,
Taf. IV, fig. 1). In 1844 Dr. Alfred King (356) announced the discovery of
"reptilian" footprints in the Carboniferous of Pennsylvania.
The next announcement of fossil Amphibia was made by Goldfuss (296), who
in 1847 described the famous _Archegosaurus_ from the upper Carboniferous
of Germany, from the remains which had as long ago as 1777 been
regarded as a fish. Two years later Isaac Lea (371) announced to the
British Association for the Advancement of Science, through Buckland,
the discovery of footprints in the old Red Sandstone (Mauch Chunk) of
Pennsylvania. These objects occur not rarely in the Mauch Chunk shales,
which are of upper Mississippian age. Barrell (21, p. 460) records the
finding of imperfect tracks in the same beds, and Rogers (Geology of
Pennsylvania, pt. II, 1856, p. 831) records three unnamed varieties from
2,200 feet below the top of the Mauch Chunk. Branson (50) has recorded
the finding of other amphibian footprints from the Mississippian of Giles
County, Virginia.
Lyell and Dawson (396), in 1853, read a paper before the Geological
Society of London, in which they announced the discovery of remains of
Amphibia in the Coal Measures of North America, although Dawson had
previously, in 1850, discovered the skull of _Baphetes planiceps_ Owen,
which was not described until the latter part of 1853 (509). The specimen
had lain unnoticed in the collection of the Geological Society for more
than two years. When, however, the announcement was made by Lyell and
Dawson of the discovery of Amphibia in the Coal Measures of Nova Scotia,
so much interest was excited that the skull, now known as _Baphetes
planiceps_, was brought to light by the president or secretary and was
described (509) by Sir Richard Owen. The only other known evidences of
land vertebrates in the Paleozoic of North America, up to this time, had
been the footprints described by Lea and King from the Mississippian
(Mauch Chunk) and Pennsylvanian of Pennsylvania. The specimens presented
to the Geological Society of London by Lyell and Dawson were found at the
South Joggins, Nova Scotia, and consisted of scutes, a few limb bones, a
fragment of a jaw, and a few vertebræ, a part of which were associated.
The remains were found quite accidentally and unexpectedly by them in
the petrified trunks of ancient Sigillariæ which were exposed on the
coast. Dr. Jeffries Wyman, of Harvard College, had examined these remains
in the United States and had pronounced (638) them to be amphibian,
comparing them with similar elements in _Menobranchus_. On the arrival
of the specimens in England they were submitted to Sir Richard Owen,
who suggested the name (514) _Dendrerpeton acadianum_ and compared the
remains with _Archegosaurus_. At the same meeting of the London Geological
Society, Owen read a paper on a small amphibian (508) from the British
Carboniferous which he named _Parabatrachus_. Subsequent discoveries have
shown, however, that this form belongs among the fishes. At the meeting
of the Geological Society held in the latter part of the same year Owen
announced (509) further discoveries in the Nova Scotia coal beds.
Hermann von Meyer (436), in 1857, described numerous stegocephalian
remains from the upper Carboniferous of Germany. Dr. Jeffries Wyman, in
the same year, described (639) a new form of amphibian from Linton, Ohio.
This form he called _Raniceps lyelli_, but as the name _Raniceps_ had been
preoccupied by Cuvier for a genus of gadid fishes, Wyman later (1868)
changed the name to _Pelion_. This was the first form to be described from
the locality at Linton, which has since yielded the remains of half a
hundred species.
Dawson (204), in 1859, made a further contribution to the fauna of
Nova Scotia by the description of _Hylonomus_ and other species of
_Dendrerpeton_ from the South Joggins deposits. Huxley (331), in 1862,
described the genera _Loxomma_ and _Pholidogaster_ from the Carboniferous
of Scotland. The same year Owen made a further contribution (514) to the
fauna of the Nova Scotia beds, and Huxley (332) discussed the anatomy of
_Anthracosaurus_ from Scotland. Marsh (404), in the next year, described,
as an enaliosaurian, the interesting _Eosaurus acadianus_ from the Nova
Scotia Coal Measures, basing the species on two vertebræ, apparently from
the dorsal region. The vertebræ resemble the stereospondylous type, and
Huxley (332) called attention to the similarity of these vertebræ to those
of _Anthracosaurus_.
Cope (105), in 1865, began his researches among the Coal Measures Amphibia
of North America by the description of _Amphibamus grandiceps_ from the
Mazon Creek shales of Illinois. Ten years later (123) he published a
complete synopsis of the Carboniferous Amphibia of North America, with
especial reference to the Linton, Ohio, species, illustrating many of
the forms now known from Linton. Between the years 1865 and 1897, Cope
published numerous papers (105-177) on the Amphibia of the Paleozoic, and
to his researches is due a large part of our knowledge of these forms.
Great credit is due Dr. J. S. Newberry (495, 498) for the enthusiasm and
interest which his collections of Coal Measures Amphibia exhibit. He
furnished Cope with the majority of the type material described by him,
and it was through Dr. Newberry's instrumentality that the "Synopsis of
the Extinct Batrachia from the Coal Measures" (123) was published. The
material which Dr. Newberry had collected he took with him from Ohio to
Columbia University, New York, and a part of his collection still remains
in the geological collection of that institution, although the greater
portion has been transferred to the American Museum of Natural History.
The Newberry collection forms the basis for the larger part of this memoir.
Between the year 1853 and the early nineties, Dawson continued (200-223)
his researches on the Amphibia of the Coal Measures of Nova Scotia. His
most notable single work (208) is "The Air-Breathers of the Coal Period,"
published in Montreal in 1863, in which he gives a complete account of
the forms then known from Canada, attempting some restorations. Since his
death there have been no new species described from Canada, and, so far as
I can learn, there has been no further collecting at the South Joggins.
Recently G. F. Matthew (409) has rearranged the classification of
amphibian footprints from Nova Scotia. Jaekel (347) has described very
fully the remains of _Diceratosaurus punctolineatus_ (Cope) from Linton,
Ohio, basing the new genus on a species described by Cope as a member of
_Ceraterpeton_. Hay (316) has added to the knowledge of the anatomy of
_Amphibamus_, his most interesting contribution being the detection of
long, curved ribs in this form. This character excludes the species from
the order Branchiosauria and shows the relationship of the form to the
Hylonomidæ and the Microsauria. Schwarz (540) has described the characters
of the vertebræ and ribs of several genera of the Coal Measures Amphibia
and has (541) offered his views as to the descent of the Amphibia, based
entirely on his work on the vertebræ of species from North America and
Europe.
Since 1908 the writer has published several contributions (457-489) on the
Amphibia from the Coal Measures of North America. The results of these
investigations are given in this work.
CHAPTER III.
STRATIGRAPHIC AND GEOGRAPHIC DISTRIBUTION OF AMPHIBIA IN THE COAL MEASURES
OF NORTH AMERICA.
There are but four localities in North America which have furnished any
notable remains of Amphibia in the Coal Measures. These are, in the order
of their discovery, the deposits at the South Joggins, Nova Scotia; the
Linton, Ohio, Coal Measures; the Mazon Creek, Illinois, shales; and the
Cannelton slates near Cannelton, Pennsylvania. There are, however, several
other localities on the continent which have furnished evidences of
Amphibia in the Coal Measures. The principal one of the latter localities
is doubtfully of Coal Measures age, although recent discoveries would tend
to show it is such. The deposits in question, those of the Clepsydrops
shales of Vermilion County, Illinois, have, heretofore, been regarded
as Permian, but the discovery of similar remains in rocks of undoubted
Pennsylvanian age in Pennsylvania would seem to indicate that the Illinois
deposits were contemporaneous with them.
[Illustration: Fig. 1. Map of Upper Pennsylvanian showing land and water
conditions under which the Coal Measures amphibian fauna lived. It will be
noted that the chief deposits which have furnished amphibian remains are
on the margins of the heavily shaded areas. (After Schuchert.)
Explanation of symbols: Lands are white. Water areas are lined. Formation
outcrops are black or dotted. Known shore-lines are solid lines; probable
ones broken. Vertical lines in middle of continent indicate Gulf marine.]
(_a_) The deposits in Vermilion County, Illinois, lie along the north bank
of Salt Fork Creek, at the tip of the "Horseshoe Bend," about 2 miles
south of Oakwood, Illinois. They were discovered by Dr. J. C. Winslow,
of Danville, in 1875. The remains discovered by him were forwarded to
Professor Cope for identification. Later the deposits were thoroughly
explored by W. F. E. Gurley, and the specimens collected by him are now
preserved (86) in Walker Museum, University of Chicago. In 1907, the
writer, while working for the University of Chicago, in exploring the
same locality, exhausted the beds so far as they could at that time be
uncovered from the landslide which had overwhelmed them. The formation
in which the bones occur is a soft gray or reddish shale, and it lies
without any apparent stratigraphic break on shales of Pennsylvanian age.
Below these shales are several feet of limestone containing invertebrates
of typical Pennsylvanian facies. There are indications of at least 3
species of Amphibia in the deposits. Case (86) has indicated with doubt a
fourth species. The species are: _Cricotus heteroclitus_ Cope, _Cricotus
gibsonii_ Cope, _Diplocaulus salamandroides_ Cope. The remains are very
fragmentary, and consist for the most part of incomplete vertebræ, with a
few small skull fragments.
(_b_) In 1897 Dr. Williston (607) described some fragments of _Cricotus_
from a deposit in Cowley County, near Winfield, Kansas. There has been
some dispute as to the age of the deposit, but the consensus of opinion
seems to be that the beds are of approximately the same age as those of
Illinois and Pennsylvania in which similar remains are found, and those
deposits are looked upon as Upper Pennsylvania (Case (94), pp. 239-240).
No new forms were described from Winfield, since only a few fragments were
obtained. Williston referred the phalange, the fragment of a jaw, and the
tooth to _Cricotus heteroclitus_ Cope.
(_c_) Later in the same year Williston (608) announced the discovery of
a tooth of typical labyrinthodont structure from near Louisville, Kansas
(plate 21, fig. 6). The tooth was accompanied by fragments of bone and was
probably not far from the bed in which it was fossilized. Williston states
that the remains were from the shales which are "nearly at the upper part
of the Carboniferous, probably within one hundred feet of the Manhattan
Limestone."
(_d_) In 1894 Marsh (406) and earlier (1873) Mudge (490) described
footprints of vertebrates from the stone-quarries near Osage City, Kansas.
The stone in which they were found was a fine-grained limestone which
occurs near the middle of the Kansas Coal Measures.
(_e_) Two years later Marsh (407) announced the discovery of traces of
the oldest known (Devonian) air-breathing vertebrate. The footprints of
_Thinopus antiquus_ were regarded by Marsh as "apparently amphibian." This
still remains the oldest geological evidence of air-breathing vertebrates,
although Lohest some years ago (381) called attention to remains from the
Devonian of France which he thought might be amphibian. The footprint
described by Professor Marsh was "found in the town of Pleasant, one
mile south of the Allegheny River, Warren County, Pennsylvania, by Dr.
Charles E. Beecher, who presented it to Yale Museum, and also furnished
the information in regard to its geological position.... The geological
horizon is near the top of the Chemung, in the upper Devonian. In the
same beds are ripple marks, mud cracks, and impressions of rain drops,
indicating shallow water and shore deposits."
(_f_) Among the collections of the American Museum there is an impression
of a small amphibian foot obtained from Phoenix Tunnel, Pennsylvania.
The impression is in hard black slate very similar to the slate of the
Cannelton region. It is possible that the specimen may have been obtained
from the Cannelton beds, since they would be expected to occur at Phoenix
Tunnel. The impression is rather small. It is the footprint of a 5-toed
animal, probably of the right foot, since no amphibian (465) so far is
known from the Coal Measures with 5 digits on the hand. The first digit
is short and thick, with a large ball at its base. The foot measures from
the posterior edge of the palm to the tip of the longest digit 12 mm. The
length of the first digit is 7 mm. The impression differs in some respects
from the impressions so far known from the Coal Measures, but no attempt
will be made to assign it to a species. It may have been made by either
a branchiosaurian or a microsaurian, but more probably the latter, since
we do not know of any of the former animals from the Cannelton beds, or in
fact from any of the Coal Measures beds excepting the Mazon Creek shales.
The specimen is No. 2872 of the American Museum.
[Illustration: Fig. 2. Distribution of Coal Measures Amphibia in North
America.
1. Linton, Ohio, near Yellow Creek P. O., Jefferson County, Ohio, on
the banks of Yellow Creek, near the Ohio River, 16 miles north of
Steubenville.
2. Mazon Creek shales, Grundy County, Illinois, near Morris.
3. "Clepsydrops shales," Salt Fork Creek, Vermilion County,
Illinois, near Oakwood, on Tate farm, 8 miles west of Danville,
Illinois.
4. Danville, Illinois, coal where the type of _Proterpeton gurleyi_
Moodie was found.
5. Breeze, Illinois, where Dr. J. A. Udden, in 1907, found a
fragment of an amphibian phalange on the dump of the Cooperative
Coal Company.
6. Pitcairn, Pennsylvania, 15 miles east of Pittsburgh.
7. Cannelton, Pennsylvania, Beaver County, Cannelton slates,
Kittanning formation, 45 miles northwest of Pittsburgh.
8. Fairfield, Iowa, where Dr. J. A. Udden found remains attributed
by Dr. Eastman to _Pleuroptyx clavatus_ Cope.
9. Louisville, Pottawatomie County, Kansas, where Dr. S. W.
Williston discovered remains of Mastodonsaurus in the Coal
Measures.
10. Washington County, Kansas, source of type of _Eobaphetes
kansensis_ Moodie, from the Coal Measures.
11. Osage City, Osage County, Kansas, amphibian footprints from the
Coal Measures.
12. Winfield, Kansas, source of Cricotus material.
13. Lander, Wyoming, in Wind River Carboniferous.
14. Pictou, Pictou County, Nova Scotia, 84 miles northeast of
Halifax. Source of _Baphetes planiceps_ Owen.
15. Joggins (Joggins Mines), Cumberland County, Nova Scotia, 4 miles
from River Hebert. Source of _Hylerpeton_ and _Dendrerpeton_
faunas.
16. South Joggins, Nova Scotia, source of the _Eosaurus acadianus_
Marsh.
]
(_g_) Dr. J. A. Udden, in 1907, discovered a fragment of a phalanx of some
amphibian (plate 22, fig. 3) on the dump of the Cooperative Coal Company,
a mile east of Breeze, Illinois. It was obtained from below the Shoal
Creek limestone and somewhere above the (Illinois) Coal No. 6, according
to Dr. Udden's notes. The maximum width of the phalanx is 10 mm. and it
probably had a length of 16 mm.
(_h_) Mr. N. H. Brown, in 1914, discovered in the Carboniferous rocks
to the east of the Wind River Mountains, near Lander, Wyoming, a single
fragment of an amphibian. The writer was accompanying Mr. Brown at the
time of the discovery and there can be no doubt that the fragment was
amphibian; the location of the beds was such that no later age than the
Coal Measures can be assigned to them.
(_i_) Dr. J. A. Udden (577), in 1912, announced the discovery of an
amphibian in the Des Moines formation of Iowa. These remains were
identified by Dr. Charles Eastman as _Pleuroptyx clavatus_ Cope. Since the
Des Moines is probably nearly contemporaneous with the Mazon Creek shales
of Illinois, the discovery does not extend the geological range to any
extent, but is of interest as it adds another note to our knowledge of the
geographical distribution of the Amphibia in the Coal Measures.
(_j_) The Gurley collection of the University of Chicago possesses a
single cervical vertebra of some amphibian (?). The vertebra is unlike
anything previously described and represents a new form (plate 22, fig. 2)
which may be designated _Proterpeton gurleyi_, new genus and species. The
material was collected near Danville, Illinois.
(_k_) Deposits have been discovered in Pennsylvania in which are found the
remains of amphibians and reptiles, very similar to those from Vermilion
County, Illinois, Cowley County, Kansas, and the Texas Permian. The
remains (plate 18, fig. 2) were found in a thin stratum below the "Ames"
limestone, and are therefore in the Coal Measures, fairly well below the
top. The fossils, as described by Case (94), consist of fragments which
he ascribes to pelycosaurian reptiles and to temnospondylous amphibians.
The genus _Eryops_ (94) is recognized in several fragments and a nearly
complete dorsal vertebral centrum. Other types of Amphibia are likewise
represented.
(_l_) The ironstone nodules, in which the Mazon Creek fossils (plate 1)
occur, are found in the shale which forms the roof of the Morris or "No.
2" Coal of Illinois, which "lies probably somewhat lower than the horizon
of the Lower Kittanning Coal of Pennsylvania" (599). "The nodules of iron
contained in the Coal shales on the banks of Mazon Creek near Morris,
Illinois, generally contain organic nuclei, and thousands of beautiful
specimens have been obtained there. They are usually fragments of fern
fronds, but are sometimes shells, crustaceans, myriapods, scorpions,
spiders, cockroaches, ... fishes" (498, p. 214), and amphibians, of which
10 species are at present known.
[Illustration: MOODIE PLATE 1
VIEWS ALONG MAZON CREEK, ILLINOIS.
1. A nodule weathering out of the shale, at the head of the hammer.
Most of the nodules at the so-called "lower beds" contain
specimens of _Neuropteris_.
2. The nodules in the creek bed at the "upper beds." Many of them
have been cracked open by the frost.
3. Looking south at the "upper beds." The nodules found in the
background are non-fossiliferous.
4. Nodules may be seen through the clear water embedded in the
shale. Neuropterid insects in the water.
5. Looking for nodules at the "upper beds." The uppermost reaches of
the fossiliferous beds correspond with the extreme background of
the picture.
6. Nodules in the stream bed at the "lower beds." Many of these are
cracked open by the frost and good specimens are sometimes found
in the nodules.
]
These species have been arranged zoologically according to the following
plan:
Class Amphibia Linné, 1758.
Subclass Euamphibia Moodie, 1909.
Order Branchiosauria Lydekker, 1889.
Family _Branchiosauridæ_ Fritsch, 1879.
_Micrerpeton caudatum_ Moodie, 1909.
_Eumicrerpeton parvum_ Moodie, 1910.
_Mazonerpeton longicaudatum_ Moodie, 1912.
_Mazonerpeton costatum_ Moodie, 1912.
Order Caudata Duméril, 1806.
Suborder Proteida Cope.
Family _Cocytinidæ_ Moodie, 1912.
_Erierpeton branchialis_ Moodie, 1912.
Subclass Lepospondylia Zittel, 1887.
Order Microsauria Dawson, 1863.
Family _Amphibamidæ_ Cope, 1875.
_Amphibamus grandiceps_ Cope, 1865.
_Amphibamus thoracatus_ Moodie, 1911.
_Cephalerpeton ventriarmatum_ Moodie, 1912.
Family _Molgophidæ_ Cope, 1875.
_Erpetobrachium mazonensis_ Moodie, 1912.
Subclass Stegocephala Cope, 1868.
Order Temnospondylia Zittel, 1887.
Suborder Embolomeri Cope, 1885.
Family _Cricotidæ_ Cope, 1884.
_Spondylerpeton spinatum_ Moodie, 1912.
It will be seen from the above arrangement that nearly all of the orders
of Amphibia are represented in the Mazon Creek fauna. These animals are
the oldest known land vertebrates of North America.
[Illustration: Fig. 3. Portion of the "Morris sheet" of the U. S.
Geological Survey, to show topography and situations of the exposures
of fossil-bearing shales at Mazon River, _a_, the "Bartlett place," the
so-called "upper beds"; _b_, "lower beds."]
The writer was able, during July 1911, to spend a week studying the
fossil beds (479) at Mazon Creek. The object of the visit was primarily
to collect Amphibia, but although several thousand nodules were examined,
not one contained an amphibian nor a fragment of one. Mr. J. C. Carr,
of Morris, Illinois, who has collected at Mazon Creek for more than 30
years, has never collected an amphibian. These facts interested me in
making the following comparison: If we take 100,000 nodules as a basis
for computation of the rarity of the various forms, something like the
following will be the approximate result of the investigation:
Of 100,000 nodules, 20,000 will be barren or contain only indeterminate
fragments; 68,500 will contain plants; 7,500 will contain insects,
Crustacea, myriapods, scorpions, spiders, and other arthropods; 3,900 will
contain fish coprolites or scales; 95 may contain fish or fragments of
fish; 4 may contain mollusks; and 1 may contain an amphibian or a fragment
of one.
Perhaps even 100,000 is low as a basis of estimate. Mr. Carr was of the
opinion that 1 nodule in every 500,000 might contain an amphibian.
The beds from which the nodules are usually collected occur along both
banks and in the bottom of the creek, in two localities. One locality
known as the Bartlett place is situated 8 miles southeast of Morris, in
Grundy County, Illinois, Wauponsee Township, N.W. quarter, section 30,
Township 33, Range 8, the land being now owned by Mrs. Emma Akerly, of
Wilmington, Illinois.
The fossil-bearing nodules occur throughout 6 to 8 feet of shale along
both banks of the creek at the "upper beds" (plate 1, fig. 3), as the
Bartlett place is called. They may also be seen in the bed of the creek,
when the water is low (plate 1, fig. 4), still embedded in the shale. With
a potato fork the shale is easily turned and the nodules come out like
potatoes. One sometimes finds a "pocket" of nodules from which as many
as a peck may be secured. Nearly every nodule has a fossil at the "upper
beds," but all of the fossils are not well preserved, possibly only 1 or
2 out of every 10 being worth carrying to the museum. The nodules crack
best when wet, and it requires some skill to crack them evenly. They seem
quite light and, in one place where the stream curves, are piled in a long
windrow. On this were found, in nodules cracked by the frost, several good
crustaceans and many good plants.
Table of Pennsylvanic Formations.
Series Northern Appalachian. Bituminous.
Pennsylvania-Ohio. Illinois.
Pennsylvanic
{
{ Coal Measures
{ { { (*) (_Salt Fork_).
{ { Monongahela or Upper { Break.
{ { Productive Coal Measures
{ {
{ { Conemaugh or Lower Barren Ames
{ { limestone near middle:
{ { (*) (_Pitcairn_) Coal No. 6.
{ {
{ { { Freeport
{ { Allegheny or Lower { (*) (Cannelton) Coal No. 2 (*).
{ { Coal Measures { Kittanning (*). (Morris?)(_Mazon Creek_).
{ { { (_Linton_).
{ { { Clarion.
{
{ Pottsville
{ {
{ { Home wood.
{ { Mercer.
{ { Conoquenessing.
{ { Sharon.
(*) marks the position of the Amphibian-producing horizons in
these regions. (After Schuchert.)
The fossils at the "upper beds" are localized into special strata. At one
place in the upper part of the deposit, in a reddish shale, one finds
that insects are more abundant than they are lower down. The Crustacea
seem to come from apparently the same shale. At the lower end of the
deposit certain definite species of _Pecopteris_ are localized. It is
an interesting fact that one seldom finds a _Neuropteris_ at the "upper
beds." The most abundant fossils are the various species of _Pecopteris_
and _Annularia_. When specimens of _Neuropteris_ are found they are
usually discovered at the lower end of the exposures. In one place behind
the "island" very blue nodules, hard and flinty and with sometimes
well-preserved specimens of _Pecopteris_, are found quite definitely
localized. These nodules are apt to assume an irregular shape. These
localizations of the fossils are, of course, what we would expect from our
knowledge of the recent fauna and flora. There is, to be sure, more or
less intermingling of the species. The myriapods, so far as they have been
found, are also localized. Mr. Carr found 3 within a space of a few feet,
but again these are found widely scattered. The exposures at the "upper
beds" are about a quarter of a mile long. They disappear under a heavy
ledge of sandy limestone.
At the "lower beds" (plate 1, fig. 6), those further down the creek,
conditions are quite different from those just described, although of the
same horizon: the banks of the creek are higher and almost perpendicular,
so that the chances of collection from the shales are fewer. The bed of
the creek, however, is wider and there are more nodules washed out. The
most abundant fossil at this place is _Neuropteris_. The nodules at the
upper end of the exposure are all, almost without exception, barren of
fossils. The exposures here are of about the same extent as the "upper
beds," though the species are not so varied. Judging from the collections
made while there, Arthropoda are more abundant at the "lower beds."
Bradley (Geol. Surv. Illinois, IV, 196, 1870) mentions the occurrence
of these nodules at or near Morris. Other than these places the nodules
have been thrown out of a coal mine near Braidwood, Illinois. Doubtless
close search would reveal other localities where the shale is cut through
in mining. The beds at both places are slightly folded. This is true
especially of the "upper beds," where a conspicuous fold caused the beds
to disappear in the bed of the creek and to reappear farther down stream.
This is directly across the large "ox-bow" bend of the creek.
The beds at Mazon Creek were first explored in 1857 by Mr. Joseph Evans,
who sent his specimens to Berlin, Germany, where they excited great
interest. It was he who collected the type specimen of _Amphibamus
grandiceps_ Cope. Since the time of Mr. Evans many have collected at Mazon
Creek, and without doubt the fossil-bearing nodules from this locality are
more widely scattered in the museums of the world than are organic remains
from any other one horizon.
So far as we know there was no upland vertebrate life at that time. The
forms at present known were confined to the water or the margins of the
water. The absence of knowledge of upland and terrestrial deposits of
this time doubtless accounts for the absence of known vertebrates. It is,
however, especially interesting to speculate on the ancestral types of the
land vertebrates, and it must be admitted that the Coal Measures Amphibia
as at present known throw the ancestry of land-living vertebrates far back
into geological time.
(_m_) The Cannelton slates of Beaver County, Pennsylvania, have furnished
3 species of Amphibia and fragments of other species are represented in
the U. S. National Museum (462). The species so far known are: _Tuditanus
minimus_ Moodie, _Erpetosaurus sculptilis_ Moodie, _Erpetosaurus minutus_
Moodie.
They are the first evidence of the occurrence of amphibian remains in
these deposits. The Cannelton specimens are found in a thin stratum of
slate which forms part of the Middle Cannelton Coal. The Cannelton slate,
in which the fossils occur, forms the roof of the Middle Kittanning Coal,
which is only 20 to 30 feet above the Lower Kittanning bed (I. C. White),
so it becomes evident that the deposition of the Cannelton slates was at
only a slightly later period than that of the shales in which the Mazon
Creek nodules occur, since the Mazon Creek shales form the roof of the
Morris, which "is probably somewhat lower than the Lower Kittanning of
Pennsylvania." From the Cannelton slates are known the remains of plants,
insects, crustacea, especially "Eurypterids found in shale immediately
below the Darlington (Upper Kittanning) Cannel Coal, near Cannelton,
Darlington Township, Beaver County, Pennsylvania, Horizon, Allegheny River
Series" (Hall, 1884). In these shales occur also, fishes and the 3 species
of amphibians referred to above. The Amphibia known from this region are
small, the largest of them not exceeding 6 inches in length.
[Illustration: Fig. 4. Portion of "West Virginia-Ohio-Pennsylvania,
Wellsville Quadrangle" of the U.S. Geological Survey, to show topography
and situation of Linton coal mines. Some fossil amphibians doubtless came
from across the line in Columbiana County.]
(_n_) The Linton, Ohio, beds outcropped near Linton post-office, which
was formerly located at the mouth of Yellow Creek, a few hundred yards
from the present station, Yellow Creek, Salem Township, Jefferson County,
in the valley of Yellow Creek, near the Ohio River, and thus near the
Pennsylvania state line.
In regard to the exact location of the town of Linton, which has long
since been abandoned, I quote from a letter from Dr. Louis Hussakof, who
visited the locality:
"The locality appears to have been known as Yellow Creek for many
years past. That is the name used in the Geological Map of Ohio
published by Orton in 1888 and which was based on the earlier maps
of Newberry (1869 and 1879). When I visited the place in 1905, and
asked for Linton (which I had not been able to locate on any map then
available to me), hardly anyone knew of such a locality. Only one old
man in Steubenville, Ohio, recalled that Yellow Creek was identical
with Linton.
"Yellow Creek is not a village, but only a R. R. station (on the
Pennsylvania R. R.), and marks a spot where once was an active
and prosperous mine. Probably at a former day there was a small
post-office somewhere in the neighborhood known as Linton. I did not
take any photographs, as I was not certain of the spot, or the mine,
from which the fossils had come. There are some cement mines within a
few minutes' walk of the station, but no coal appears to be mined at
present at Yellow Creek. 'Smith's Pit,' the coal mine best remembered
by the younger men, is not worked.
"Now as to the question whether some of the Amphibia might have come
from localities in Columbiana County. I believe it very probable that
they did. I walked along the road from Yellow Creek (Jefferson County)
to Wellsville (Columbiana County), a distance of about 2 or 2.5 miles,
and the country seemed quite the same. Everywhere one sees outcrops
of coal in the cuts along the road. Furthermore, I inclose a copy of
a page in an old notebook of Professor Newberry from which you will
see that Coal Measure fossil localities were known not only at Yellow
Creek, but also from near Wellsville. There can be hardly a doubt that
most of the specimens you have are from Yellow Creek; and quite a
number are those collected by Sam Huston."
Newberry says, in regard to the fauna of the Linton Coal:
"The Linton locality is especially interesting and instructive. It
has already (1889) yielded more than 20 species of fishes and nearly
40 species of aquatic amphibians, all inhabitants of the same body
of water. These were found in a thin stratum of cannel which, over
a limited area, underlies a thick bed of cubical coal (No. 6 of the
Ohio reports), of which the place is near the top of the Lower Coal
Measures. At Linton, ... we have evidence that the great marsh in
which the peat accumulated that formed coal No. 6 was for a time a
lake or a lagoon, inhabited by the fishes and amphibians to which I
have referred.... Many of the fishes and the amphibians were highly
carnivorous and powerful, as we learn from their teeth and coprolites.
The largest of the amphibians must have been 8 or 10 feet in length,
having strong jaws, set with numerous lancet-shaped teeth an inch
or more in length.... After a sufficient time had elapsed for many
generations of fishes and aquatic salamanders to live and die, the
lake was filled by the extension of its peaty shores into it just as
so many lakelets are filled and obliterated at the present time and
afterward over the cannel was formed a mass of peat, which has now
become a stratum of cubical coal 7 feet in thickness.
"In the Linton cannel are buried fragments or entire individuals of
all the inhabitants of this body of water which had hard parts, bones,
scales, spines, or teeth, capable of preservation. Hence we get a
locally complete picture of the life of the Carboniferous age, and we
find it to be unexpectedly rich and varied. In that age fishes and
amphibians were the highest forms of animal life, and the amphibians
were comparatively newcomers on the earth's surface. Yet they had
multiplied and differentiated until this little pool contained
millions of them, varying in length from 6 inches to 10 feet and
curiously diversified in their forms, their scales, and spines, and in
the ornamentation of their enamel-covered heads" (498).
"To the paleontologist there are few places in the world more
interesting than the Diamond mine, at Linton, since here we get such
a view of the life of the Carboniferous age as is afforded almost
nowhere else, and of the great numbers of species found there, not
more than three or four have been met with elsewhere" (497).
On page 18 is a list of the Amphibia which are thus far described from the
Linton deposits. They all belong, so far as known, to the Microsauria, the
reference of any of the species to other orders being doubtful. The larger
Amphibia seem to be indicated by a large rib which resembles very much
that described by Huxley in 1863 for _Anthracosaurus_.
Amphibia from the Linton Beds (51 SPECIES).
_Brachydectes newberryi_ Cope. Fragment of a skull.
_Cercariomorphus parvisquamis_ Cope. Impression of body.
_Cocytinus gyrinoides_ Cope. A skull and anterior dorsal vertebræ.
_Ctenerpeton alveolatum_ Cope. Large portion of skeleton, no skull.
_Diceratosaurus lævis_ Moodie. Complete skull.
_Diceratosaurus punctolineatus_ Cope. Anterior vertebræ, part of skull,
with ribs and portion of ventral armature.
_Diceratosaurus robustus_ Moodie. Incomplete cranium.
_Eoserpeton (Ceraterpeton) tenuicorne_ Cope. Incomplete skull.
_Erpetosaurus acutirostris_ Moodie. Complete skull.
_Erpetosaurus obtusus_ Cope. Incomplete skull.
_Erpetosaurus radiatus_ Cope. Incomplete skull.
_Erpetosaurus tabulatus_ Cope. Incomplete skull, with clavicles.
_Erpetosaurus tuberculatus_ Moodie. Incomplete skull.
_Eurythorax sublævis_ Cope. A single interclavicle. (Operculum of lung
fish, _Sagenodus_.)
_Hyphasma lævis_ Cope. Incomplete skull and anterior vertebræ.
_Ichthycanthus ohiensis_ Cope. Portion of dorsal region.
_Ichthycanthus platypus_ Cope. Posterior portion of body.
_Leptophractus dentatus_ Moodie. Mandible.
_Leptophractus lineolatus_ Cope. Incomplete skull.
_Leptophractus obsoletus_ Cope. Portions of skull.
_Macrerpeton deani_ Moodie. Mandible and part of skull.
_Macrerpeton huxleyi_ Cope. Part of cranium.
_Molgophis brevicostatus_ Cope. Part of vertebral column with ribs.
_Molgophis macrurus_ Cope. Vertebral column.
_Molgophis wheatleyi_ Cope. Part of skull with 25 vertebræ.
_Odonterpeton triangularis_ Moodie. Skull and anterior part of body.
_Œstocephalus rectidens_ Cope. Part of mandible.
_Œstocephalus remex_ Cope. Skull and anterior part of body.
_Pelion lyelli_ Wyman. Cranium, fore part of body, hind limb.
_Phlegethontia linearis_ Cope. Skull and anterior part of body.
_Phlegethontia serpens_ Cope. Series of 22 dorsal vertebræ.
_Pleuroptyx clavatus_ Cope. Part of vertebral column and limbs.
_Ptyonius marshii_ Cope. Part of skull and anterior vertebræ.
_Ptyonius nummifer_ Cope. Skull and greater part of vertebral column.
_Ptyonius pectinatus_ Cope. Many specimens, some nearly perfect.
_Ptyonius serrula_ Cope. Nearly complete skeleton.
_Ptyonius vinchellianus_ Cope. Skull and anterior vertebræ.
_Saurerpeton latithorax_ Cope. Skull and fore part of body.
_Sauropleura digitata_ Cope. Greater part of body minus skull.
_Sauropleura (Anisodexis) enchodus_ Cope. Part of jaw.
_Sauropleura foveata_ Cope. A single interclavicle with impression.
_Sauropleura longidentata_ Moodie. Incomplete skull with mandible.
_Sauropleura newberryi_ Cope. Two incomplete skulls with vertebræ.
_Sauropleura pauciradiata_ Cope. Elements of a pectoral arch.
_Sauropleura scutellata_ Newberry. Imperfect skeleton.
_Stegops divaricata_ Cope. Nearly complete skull.
_Thyrsidium fasciculare_ Cope. Dorsal vertebræ.
_Tuditanus brevirostris_ Cope. Skull and anterior vertebræ.
_Tuditanus longipes_ Cope. Part of vertebral column with limbs.
_Tuditanus punctulatus_ Cope. Skull and anterior part of body.
_Tuditanus walcotti_ Moodie. Skull and portions of body.
Besides the above-listed species there are others indicated by fragments
too poorly preserved to be worthy of specific designation. The Linton
Amphibia are all apparently confined exclusively to that locality. Species
from the Cannelton slates have been assigned, however, to genera which
occur at Linton, _i.e._, _Erpetosaurus_ and _Tuditanus_. This reference
may be due to lack of knowledge, as the forms are insufficiently known. A
single Linton species has been assigned to _Ichthyerpeton_, a genus known
otherwise only from the Coal Measures of Kilkenny, Ireland. Cope referred
species from Linton to the genus _Ceraterpeton_ of Huxley, from Kilkenny,
Ireland, but Jaekel (347) and the writer (462) have shown that the
species were incorrectly assigned to the genus _Ceraterpeton_, and that
in fact they represent widely distinct genera. A single species has been
identified by Eastman from the Des Moines limestone of Iowa as identical
with one from Linton, _Pleuroptyx clavatus_ Cope. The Linton fauna is
distinct from that of the Mazon Creek beds, and also from that of South
Joggins, Nova Scotia.
(_o_) The deposits in Nova Scotia have been correlated with the Coal
Measures strata of the United States (Bell, Summ. Rpt. Geol. Surv. Canada,
1912, 1914, 360-371). They are very near the same age as the Linton beds
and come in near the base of the Allegheny River series. The exposures
are at the South Joggins, along the sea-coast. Here in strata of clay
interstratified with coal are found the erect stumps of the Sigillariæ,
and it was in the rock within these stumps that Lyell and Dawson, in 1853,
discovered the remains of the amphibians which they termed "reptiles."
"The bones of Dendrerpeton hitherto found, as well as those of the
smaller species, have been obtained from the interior of erect
Sigillariæ, and all of those in one of the many beds which, at the
Joggins, contain such remains. The thick cellular inner bark of the
Sigillaria was very perishable; the slender woody axis was somewhat
more durable; but near the surface of the stem, there was a layer of
elongated cells, or bast tissue of considerable durability, and the
outer bark was exceedingly dense and indestructible. Hence an erect
tree, partly imbedded in sediment, and subjected to the influence of
the weather, became a hollow shell of bark. When they remained open
for a considerable time, they would constitute pitfalls into which
animals walking on the surface might be precipitated. When the surface
was inundated all such remains would be covered and imbedded in the
sediment. These seem to have been the precise conditions of the bed
which afforded these remains." (Dawson, 223, 1894.)
Fifteen species have been described from the Joggins deposits. Two are
known from the Albion mines, south Nova Scotia, where were obtained the
remains of _Baphetes planiceps_ Owen and _B. minor_ Dawson.
The following 17 species of Amphibia are known from the Carboniferous of
Canada:
_Amblyodon problematicum_ Dawson. Teeth and fragments.
_Baphetes minor_ Dawson. An incomplete mandible.
_Baphetes planiceps_ Owen. An incomplete cranium from Albion.
_Dendrerpeton acadianum_ Owen. A jaw, limb bones, and fragments.
_Dendrerpeton oweni_ Dawson. Phalangeal bone and fragments.
_Eosaurus acadianus_ Marsh. Two dorsal vertebræ.
_Fritschia curtidentata_ Dawson. A mandible, vertebræ, ribs.
_Hylerpeton dawsoni_ Owen. Mandible, teeth and incomplete maxilla.
_Hylerpeton intermedium_ Dawson. Mandible and portions of skull.
_Hylerpeton longidentatum_ Dawson. Fragments of mandible and skull.
_Hylonomus latidens_ Dawson. Mandible and teeth.
_Hylonomus lyelli_ Dawson. Incomplete skeleton and part of skull.
_Hylonomus multidens_ Dawson. Fragments of skull.
_Hylonomus wymani_ Dawson. Mandible and vertebræ.
_Platystegos loricatum_ Dawson. Incomplete skull, vertebræ.
_Smilerpeton aciedentatum_ Dawson. Teeth, ribs, fragments.
_Sparodus_ sp. indet. Teeth, scales.
(_p_) All the remains representing the above species were collected by
Sir J. William Dawson at the South Joggins and at the mines of Albion,
with the exception of _Eosaurus_, which was collected by O. C. Marsh.
The collections of Dawson are now in the Peter Redpath Museum of McGill
University in Montreal and in the British Museum of Natural History at
South Kensington, London. The history of the discovery of the deposits and
their amphibian fossils at the South Joggins is so interesting that it
was thought worth while to reproduce in large part Dawson's paper "On the
Mode of Occurrence of Remains of Land Animals in Erect Trees at the South
Joggins, Nova Scotia," published in 1891 in the Transactions of the Royal
Society of Canada, section IV, p. 127:
"The remarkable section of coal-formation rocks at the South Joggins,
in Cumberland County, has long been known as one of the most
instructive in the world; exhibiting as it does a thickness of 5,000
feet of strata of coal-formation in a cliff of considerable height,
kept clean by the tides and waves, and in the reefs extending from
this to the shore, which at low tide expose the beds very perfectly.
It was first described in detail by the late Sir W. E. Logan (Report
Geol. Surv. Canada, 1844), and afterwards the middle portion of it
was still more detailed by the author (Dawson), more especially in
connection with the fossil remains characteristic of the several beds
and the vegetable constituents and accompaniments of the numerous
seams of coal (Jour. Geol. Soc. Lond., X, p. 1, 1853). It was on
occasion of a visit of the author in company with Sir Charles Lyell,
and in the pursuit of these investigations, that one of the most
remarkable features of the section was disclosed in 1851. This is
the occurrence, in the trunks of certain trees imbedded in an erect
position in the sandstones of Coal-mine Point, of remains of small
reptiles, which with one exception, a specimen from the Pictou
coal-fields, were the first ever discovered in the Carboniferous rocks
of the American continent, and are still (1891) the most perfect
examples known of a most interesting family of coal-formation animals,
intermediate in some respects between reptiles proper and batrachians,
and known as Microsauria. With these were found the first-known
Carboniferous land snails and millipedes. Very complete collections of
these remains have been placed by the author with his other specimens
in the Peter Redpath Museum and in the British Museum.
"A forest or grove of the large ribbed trees known as _Sigillariæ_ was
either submerged by subsidence or, growing on low ground, was invaded
with the muddy waters of an inundation, or successive inundations,
so that the trunks were buried to the depth of several feet. The
projecting tops having been removed by subaerial decay, the buried
stumps became hollow, while their hard outer bark remained intact.
They thus became hollow cylinders in a vertical position and open
at the top. The surface having then become dry land, covered with
vegetation, was haunted by small quadrupeds and other land animals,
which from time to time fell into the open holes, in some cases nine
feet deep, and could not extricate themselves. On their death, and
the decomposition of their soft parts, their bones and other hard
portions remained in the bottom of the tree intermixed with any
vegetable debris or soil washed in by rain, and which formed thin
layers separating successive animal deposits from each other. Finally,
the area was again submerged or overflowed by water, bearing sand
and mud. The hollow trees were filled to the top and their animal
contents thus sealed up. At length the material filling the trees was
by pressure and the access of cementing matter hardened to stone, not
infrequently harder than that of the contained beds, and the whole
being tilted to an angle of 20°, and elevated into land exposed to
the action of the tide and waves, these singular coffins present
themselves as stony cylinders projecting from the cliff or reef, and
can be extracted and their contents studied. The singular combination
of accidents above detailed was, of course, of very rare occurrence,
and, in point of fact, we know only one set of beds at the South
Joggins in which such remains so preserved occur; nor is there, so
far as I am aware, any other known instance elsewhere. Even in the
beds in question, only a portion of the trees, about 15 out of 30,
have afforded animal remains. We have, however, thus been enabled to
obtain specimens of a number of species which would probably otherwise
have been unknown, being less likely than others to be preserved in
properly aqueous deposits. Such discoveries on the one hand impress
us with the imperfection of the geological record; on the other, they
show us the singular provisions which have been made in the course of
geological time for preserving the relics of the ancient world, and
which await the industry and skill of collectors to disclose their
hidden treasures.
"There is evidence in coprolitic matter on one of the surfaces within
the trunks, and also in certain trails on these surfaces, that some of
the imprisoned animals lived for a time in their subterranean prisons;
that they crept around their walls in search of a way of escape, and
that the larger animals fed on smaller species entrapped along with
them."
After the discovery of these entombed amphibians Sir William Dawson was
given a grant of £50 from the Government Fund by the council of the
Royal Society of London, to aid in the extraction of these trees and the
collection of their contents. The trees were carefully taken out and
their contents examined; the portions containing the animal remains were
carefully boxed to be taken to Montreal for final cleaning and study.
Erosion goes on rapidly at the South Joggins, but no one has paid any
attention to the occurrence of Amphibia along the coast of Nova Scotia
within recent years.
[Illustration: Fig. 5. Dawson's tree No. 13 at the South Joggins, Nova
Scotia. Upper part, _in situ_, in the reef after it had been exposed by
blasting. (After Dawson, based on a photograph.)]
(_q_) A deposit which will be of undoubted interest in connection with
the occurrence of Amphibia in the Coal Measures is that which outcrops
along the banks of Rock Creek in the South western part of Douglas County,
Kansas, in Marion Township (Township 14 south, Range 18 east, SW. and SE.
quarters of section 7), about 2 miles from the now-abandoned post-office
of Twin Mounds, so called from the two flat-topped, elongated mounds of
Oread limestone to the west of the town.
The interest in these beds is not due to the discovery of Amphibia in
them, but the possibilities of such discoveries. This is indicated by the
occurrence of fossils, in nodules similar to those obtained from Mazon
Creek, which are identical generically, nd in most cases specifically,
with the Mazon Creek animals and plants.
The fossils so far collected from this interesting locality are:
Insecta (Identified by Dr. E. H. Sellards).
_Spiloblattina maledicta_ (Scudder). The basal half of a front wing.
_Etoblattina_ sp. The hind wing of a cockroach.
Arachnida.
_Anthrocomartus_. Impression of the body.
_Prestwichia danæ_ M. & W. Nearly complete specimen.
Crustacea.
_Acanthotelson stimpsoni_ M. & W. Three nearly complete individuals.
Plants (Identified by Mr. J. C. Carr, of Morris, Ill.).
_Pecopteris_ sp.
_Sagittaria reticulata_ Lesquereux.
_Annularia longifolia_ Lesquereux.
_Annularia inflata_ Lesquereux.
_Pecopteris villosa_ Brongniart.
_Neuropteris decipiens_ Lesquereux.
_Pecopteris serpulifolia_ Lesquereux. By far the most abundant plant
is _Pecopteris_.
The fossils occur in definite strata of nodules immediately above a
10-inch coal seam which is worked for local consumption. The coal lies
near the base of the exposure in the more western portion of the outcrop,
but it is raised by an anticlinal fold to near the top of the creek-banks
by the bridge across Rock Creek, along the banks of which the shales are
exposed. Nodules containing fossils are found most abundantly at the
western exposure on the McKinzie place, only a few having been found near
the bridge.
Below the coal-seam, nodules of various shapes and sizes occur, but they
seldom contain fossils and never good ones. Occasionally, as at Mazon
Creek, fragments of plants adhere to the outside of the incrusting shale.
A single nodule may have adhering to it fragments of 4 genera of plants.
The fossiliferous nodules all occur above the coal and are most prolific
and abundant immediately above the seam, within the first 10 inches. In
the same stratum of shale with the nodules are found abundant impressions
of plants in the shale, often perfect fronds being uncovered. (See, in
this connection, Twenhofel and Dunbar, 1914, "Nodules with Fishes from the
Coal Measures of Kansas," Amer. Journ. Sci., XXXVIII, pp. 157-163.)
G. F. Matthew (408-413) has described numerous genera and species of
footprints, presumably amphibian, from the Carboniferous of Canada. The
impressions indicate small creatures for the most part. Other imprints
have been described by Logan, Dawson, Lyell, Marsh, Mudge, and Lea. Since
the present work is intended largely for a morphological review, only
passing notice can be given to the _ichnites_. The literature on the
"Ichnites" has been brought together in Hay's "Bibliography and Catalogue
of Fossil Vertebrata of North America," pp. 538-553. References since the
publication of Hay's catalogue (317) will be found in the bibliography at
the end of this work. Footprints are of interest in that they are the only
evidence we have of the occurrence of land vertebrates in the Devonian and
Mississippian of North America.
CHAPTER IV.
THE MORPHOLOGY OF THE COAL MEASURES AMPHIBIA.
The anatomy of the Coal Measures Amphibia presents many primitive types
of structure. Their organization represents a stage passed through
in the ontogeny of higher vertebrates. The animals are similar in a
general way, yet so diverse are the modifications which they have
suffered under different environmental conditions, that close scrutiny
is needed to discern the exact relationship of the forms. Our knowledge
of this relationship is based on the structures preserved, which are
largely skeletal, since little is known of the soft anatomy (471) of the
air-breathing vertebrates of the Coal Measures. The pubis is ossified in
the Paleozoic Amphibia later than the ischium and ilium; the carpus and
tarsus are cartilaginous; the vertebræ consist of a pleurocentrum and two
neurocentra, thus paralleling conditions in modern mammalian embryos.
[Illustration: Fig. 6.--Generalized figure of dorsum of an early amphibian
skull to show position of elements and terminology adopted in this work.
The outline is based on that of _Eryops_, but is in no way intended to
indicate that form.
_a. com_, anterior commissure of lateral-line canals; _com_, commissural
communication between infra- and supra-orbital lateral-line canals; _fr_,
frontal; _inf_, interfrontal; _inn_, internasal; _info_, infraorbital
lateral-line canal; _it_, intertemporal; _jl_, jugal lateral-line canal;
_j_, jugal; _lar_, lacrimal; _mx_, maxilla; _n_, nasal; _oc_, occiput;
_occ_, occipital cross-commissure of the lateral-line system; _or_,
orbit; _par_, parietal; _pof_, postfrontal; _pmx_, premaxilla; _pf_,
prefrontal; _po_, postorbital; _pp_, postparietal; _g_, quadrate; _qj_,
quadratojugal; _spo_, supraorbital lateral-line canal; _sq_, squamosal;
_spt_, supratemporal; _t_, temporal lateral-line canal; _tab_, tabulare.]
(_a_) The skull of the Coal Measures Amphibia has (fig. 6) essentially
the same structure in the different groups. It is largely formed of
bones of intramembranous origin, representing the _face_ bones of the
mammalian skull. The skull in life was doubtless a _chondrocranium_ with
the membrane bones laid down upon the cartilaginous box containing the
sense-organs, as in the sturgeon (_Acipenser_), where the surface bones of
the face were probably originally scales, which later became consolidated
into large bony scutes. The membrane bones of the early Amphibia may have
been originally derived from scales, but at present nothing is known of
this origin; doubtless the elements had an intramembranous origin in the
ancestors of the group. Judging from Credner's studies on the series
of specimens of _Branchiosaurus amblystomus_ Credner (187), the skull
bones do not ossify completely until relatively late in the life of the
individual. The skull in the youngest individual figured by Credner
(_op. cit._, Taf. XVI, fig. 1) seems to be largely cartilaginous, with
beginnings of separation into the skeletal elements. The manner and
time of development and ossification of the skull seems to proceed much
as it does in modern amphibians. The condition found in the skull of
_Cryptobranchus allegheniensis_ or _Necturus maculosus_ will represent
pretty accurately the condition of most of the Coal Measures Amphibia. The
face bones in certain forms were sculptured and cut by lateral-line canals.
A median suture divides the skull into two equal regions dorsally. On
the sides of this median suture lie pairs of elements which are common
to all higher vertebrates. These elements are: the premaxillæ, nasals,
frontals, parietals, and post-parietals. All of these elements vary
somewhat in shape and slightly in arrangement, but always occupy the same
relative positions. To the side of these elements lie the prefrontal, the
postfrontal, the supratemporal, the squamosal, and tabulare, and occupying
the margin of the skull are the maxilla, the jugal, the quadratojugal, and
possibly the quadrate in a few forms. The parietal foramen occurs usually
within the parietal bone, but its position is subject to slight variations
and it may occur on the suture between the frontal and the parietal, or
even far posterior near the postparietal. The nostrils often lie well
forward and are included by the premaxillæ, nasals, and prefrontals. The
orbit is usually well posterior, but it may occur far forward. It is
bounded by the prefrontal, the frontal, the postfrontal, the post-orbital,
and the jugal. Sometimes the lacrimal is present and has been clearly
identified on the anterior margin of the orbit in a few cases.
(_b_) _Sclerotic plates_ often occur within the orbits, and are not
confined to any particular group, though they are quite constant among
the Branchiosauria. They are usually delicate, thin, broad plates which
evidently overlap and operate as in modern animals. The number varies, as
many as 30 occurring within the orbit of one branchiosaur. Between the
margin of the orbit and the sclerotic plates there often occur, in the
Branchiosauria (186) particularly, small scale-like particles which were
doubtless embedded in the heavy skin above the orbit during life.
(_c_) The _palate_ of the skull is very incompletely known, being
indicated in a very few cases. These specimens, however, show that
the characters of the palate were quite similar, if not identical, in
essential respects with the palate among the European species of the same
or slightly later time.
A large cultriform parasphenoid occupies the posterior portion of the
palate, on either side of which in some species lies the posterior
palatine foramen. On the sides of the anterior prolongation of the
parasphenoid lie the vomers (186), membranous bones often bearing minute
tubercular teeth, apparently adapted for crushing. The vomers and the
maxillæ, with sometimes the palatine, surround the anterior palatine
foramen, which is almost always present; sometimes, however, quite small.
The transverse or ectopterygoid unites the pterygoid, a broad plate of
thin bone, with the maxilla and jugal.
(_d_) The teeth of the Coal Measures Amphibia (194) are remarkably similar
in the various forms. They are always slender, pleurodont denticles
arranged in a single row on the jaws or as tubercular eruptions on the
palate bones, with a large pulp-cavity and the enamel often striated. The
food of the creatures must have been small Crustacea, worms, insects, and
succulent vegetation, such as is the food of the modern Amphibia.
(_e_) The _occiput_ is formed of partially ossified (465) ex- and
basi-occipitals, though these elements are never firmly united by ossific
union. Often a pair of condyles occur, one on either exoccipital. The
occiput was usually, however, cartilaginous and no trace of its structure
is preserved.
(_f_) The _mandible_ is usually as long as the skull and is slender. It
is composed of 6 elements so far as known (465); these are the articular,
the surangular, the angular, the coronoid, the dentary, and the splenial.
Other elements may be present, but the anatomy of this portion of the
animals is not very completely known. The bones are sculptured and cut by
lateral-line canals (458) in a few forms. Whether the articular operated
on an osseous or cartilaginous quadrate is unknown, though certain
specimens seem to indicate an osseous condition for that element. The
anterior symphysis was doubtless ligamentous, the halves always separating
before fossilization. The dentary always bears a single row of pleurodont
teeth, which may vary greatly in size and number.
(_g_) The _hyoid apparatus_ is well preserved in a few forms (123).
Doubtless it was present in all of them, though it has seldom been
preserved. The condition of the hyobranchial apparatus in _Cocytinus
gyrinoides_ (text-fig. 16) from the Coal Measures of Linton, Ohio,
seems to indicate that the species was a perennibranchiate salamander
(123). It is well known from the studies of Credner that the European
Branchiosauria, in the young, possessed external branchiæ (187) supported
by lateral basibranchials. The gill-arches seem to have been slightly
calcified or ossified in a few cases, and they supported denticle-like
projections which bore the gill-filaments. When the Branchiosauria had
attained a length of 100 mm. or more they lost their gills (187). This
change was accompanied by the reduction of the tail, expansion of the
pelvis, and increase in ossification of the skull and skeletal elements.
Gills have not yet been detected among the American Branchiosauria.
(_h_) The _eye_ in a few species had a large amount of black pigment,
as indicated by the blackening of the stone in the Mazon Creek nodules.
Professor Cope (107) thought that this would indicate a nocturnal and
crepuscular habit for these vertebrates, since the _pigmentum nigrum_ of
the choroid is largely developed. Other than this suggestion nothing is
known of the soft parts of the head.
(_i_) The _alimentary canal_ (text-fig. 7) is beautifully preserved
as a cast in three specimens of the American branchiosaur species
_Eumicrerpeton parvum_ Moodie (471) from the Mazon Creek beds. The nodules
which contain these interesting little fossils measure less than 3 inches
in long diameter. The fossil salamanders, about 30 mm. in length, are
preserved on their backs and occur as nearly as is possible in the center
of the nodule.
If it were not for the fact that the œsophagus became loosened and dropped
from its place shortly after death, the alimentary canal would be in
place and would immediately recall a freshly dissected specimen of a
recent salamander. The anterior end of the œsophagus lies obliquely across
the chest region with its tip pointing slightly downward. The length
of the œsophagus proper, in one specimen, is only about 3 mm. As it is
preserved, the œsophagus lies in a semi-sigmoid curve with the convexity
anterior, and enters the cardiac portion of the stomach by a gradual
constriction. The stomach is clearly preserved as a distinct sac-like
organ with two lobes which correspond to the cardiac and pyloric limbs.
It measures about 7 mm. in length by 2 mm. in its greatest diameter.
The muscular constriction which divides the organ into pyloric and
cardiac divisions occurs at a distance of 4 mm. from the upper end. The
pylorus is designated by a rather pronounced constriction which may be
partly accidental, although it recalls the pylorus of modern frogs. From
this constriction, which lies on the left side of the fossil, as it is
preserved, the duodenal portion of the intestine makes a straight course
posteriorly to near the anal region, where it takes a sharp bend and
curves back to run parallel with itself for the distance of 4 mm. In its
upward course the intestine enlarges, and practically the same enlargement
continues throughout the remainder of the course to the anus. At a
distance of 1 mm. from the anal end, the rectum dilates probably 0.125
mm. to form the cloaca. After the intestine has continued its parallel
course for the 4 mm., as above stated, it turns abruptly to the right for
a distance of 2 mm. It then runs posteriorly for a short distance, then
bends back and under itself to again make a double sigmoid curve, when at
a distance of 6 mm. from the anus it assumes a straight course, which it
continues to the end.
[Illustration: Fig. 7.--Alimentary canal of Coal Measures salamander as
illustrated by the smaller specimen of _Eumicrerpeton parvum_ Moodie, from
the Mazon Creek shales. × 3. Original in Yale University Museum. _a_,
anus; _dd_, duodenum; _in_, intestine; _l_, impression of liver(?); _oes_,
œsophagus; _st_, stomach.]
The anus lies at a level which is approximately that of the lower end
of the femur, which is preserved as an impression on the left side of
the fossil, thus agreeing in its position with that found in modern
Caudata. Lying inside the curve of the stomach and partly inclosed by the
œsophagus is a smooth area which may possibly represent the impression
of some of the accessory digestive glands, such as the liver. Occurring
in this smooth area are numerous fine lines which possibly represent the
impressions of blood-vessels; but they are so imperfectly preserved that
one can not be sure.
Representatives of several genera of the modern Caudata have been
dissected in order to make a direct comparison of the fossil alimentary
canal with that of the recent forms. The alimentary tract of _Desmognathus
fuscus_ Raf. from the vicinity of Ithaca, New York, resembles in a
marked degree that of the fossil form. The nearest approach to the
condition there represented is found, however, in an immature branchiate
individual, some 47 mm. in length, of _Diemyctylits torosus_ Esch., from
a fresh-water pond on Orcas Island in Puget Sound. The presence of this
species on the island is very suggestive. It is of extreme interest, too,
that the condition represented in the alimentary tract of the fossil
branchiosaurs should resemble so closely that of an immature rather than a
mature form.
(_j_) The vertebral column is clearly and readily separable into cervical,
dorsal, sacral, and caudal regions. The neck is always short, with from
5 to 10 vertebræ, cervical ribs often present. The dorsal region is not
long, but varies from 20 to 30 in the constituent vertebræ. There is a
single sacral vertebra not always to be readily distinguished from those
of the dorsal and anterior caudal series. The tail may be very short
or extremely long, with neural and hæmal spines elongate and flattened
into an oar-like appendage. The distal caudals are in some species
cartilaginous, apparently always so in the Branchiosauria.
(_k_) The _atlas_ and _axis_ are unknown among the American specimens, but
we are able to infer from the structure of the other vertebræ what this
must have been; and our inferences are partly confirmed by the conditions
existing in the European forms (187). The atlas, apparently, consisted of
a pair of neurocentral plates which are partly ossified, partly embedded
in cartilage, judging from the edges of the plates which have been
preserved. The centrum seems not to have been present in the atlas, or if
present it was only very slightly developed and quite free from the neural
pieces and largely embedded in cartilage. A fairly accurate picture of the
condition of the _atlas_ and _axis_ may be seen on examining a cow, pig,
or chick embryo (378) in the early stages of vertebral development, which
has been cleared by the Schultze method (Amer. Journ. Anat., VII, No. 4,
1908).
(_l_) The _dorsal vertebræ_, as well as those of the other series, present
a primitive character (fig. 8) in the persistence of the notochord
(540). Among the Branchiosauria the notochord was not at all or but
slightly constricted intravertebrally, but among the Microsauria it was
constricted so far that the notochordal remnants in each centrum resemble
an hour-glass.
The structure of the vertebræ among American forms agrees fully with that
outlined by Credner, Fritsch, and others for the European species. The
details of structure are so fully given by Zittel (642, pp. 346-353) and
by Schwarz (540, 541) that it will not be necessary to state more here
as to their structure, since there is nothing new to add concerning the
American species.
The temnospondylous vertebra of the same nature and type as exhibited by
the Permian forms has its representatives (94, 478) in the Coal Measures.
_Spondylerpeton spinatum_ Moodie (478) (plate 4, figs. 1, 2) and _Eryops_
sp. (plate 18, fig. 2) indicate the embolomerous and rachitomous types
of vertebral structure. The occurrence of these widely different types
of vertebral structure indicates a long history for the group prior to
the Coal Measures. This history is further indicated by footprints in the
Mississippian and Devonian of this continent.
[Illustration: Fig. 8.--Vertebræ and ribs of Amphibia from the Coal
Measures of Linton, Ohio. Originals in Geol. Inst. Berlin. (All after
Schwarz.)
A. Caudal vertebra of _Œstocephalus remex_ Cope. Lateral view. × 4.
B. Caudal vertebra of _Ptyonius vinchellianus_ (?) Cope. Lateral
view. × 6.
C. Dorsal vertebra of _Ptyonius pectinatus_ Cope. Lateral view. × 9.
D. Notochordal cones and spinal canal of _Thyrsidium fasciculare_
Cope. × 3.
E. Rib of Molgophis sp. Cope. × 1.75. _c_=capitulum; _t_=tuberculum.
F. Vertebra of _Molgophis_ sp. Cope, from ventral side. × 2.
G. Dorsal vertebra of _Ptyonius pectinatus_ Cope. From above. × 8.
H. Dorsal vertebra of _Thyrsidium fasciculare_ Cope, from below. ×
2.5.
I. Vertebra of _Phlegethontia linearis_ Cope, from above. × 5.5
J. Rib of _Œstocephalus remex_ Cope, from posterior dorsal region. ×
5.
K. Dorsal vertebra of _Thyrsidium fasciculare_ Cope, from above. ×
1.5
L. Anterior dorsal vertebra (cervical?) of _Thyrsidium fasciculare_
Cope. Lateral view. × 1.5.
M. Vertebra of _Phlegethontia linearis_ Cope, from side. × 5.
]
(_m_) The _ribs_ (fig. 8) are very diverse in structure and in their
mode of articulation (541) with the vertebral column. The characters
of the ribs and vertebræ constitute the best means of classification
of these animals so far discovered. In the Branchiosauria the ribs are
always straight, heavy, and short, and articulate intravertebrally upon a
large and strong transverse process. They occur throughout the vertebral
column. There is a single pair of sacral ribs which are not to be clearly
distinguished from the pre-sacral and post-sacral series. The cervical
and caudal ribs are shorter than the dorsal series. The branchiosaurian
rib is composed almost entirely of perichondral ossification. It presents
the same condition as does the humerus of the cow embryo of 2 to 3 inches
in length. The ribs of the branchiosaurs are identical in every way with
the ribs of modern salamanders and form one of the strong arguments in
favor of the relationship of the Branchiosauria to the Caudata. Among the
Microsauria the ribs are always long, slender, curved, and intercentral.
They may be either single or double headed, but usually the former. They
resemble in their characters the ribs of some of the early reptiles and
an attempt has been made to relate the Microsauria (469) to the primitive
reptiles on this basis. The ribs of the other groups are still unknown.
Indeed, representatives of the Temnospondylia and the Stereospondylia are
very scanty in the American Coal Measures. One large rib (plate 22, fig.
4) may represent a labyrinthodont, but nothing is known of the species to
which the rib belonged.
(_n_) The _pectoral girdle_ (187) is a very simple and uniform structure,
although the details of the association of the elements still remain to
be determined. A single, median, usually large and elongate interclavicle
occupies the ventral line of the chest. This is morphologically the same
element which occurs in the middle line of the chest of the lizards.
It is a dermal bone and is usually, especially among the Microsauria
(462), highly sculptured. It varies considerably in size and shape, but
is remarkably uniform throughout the various groups. Lying anterior to
the interclavicle and overlapping its antero-lateral margins lie the two
clavicles, which are usually diamond-shaped and are sculptured, dermal
bones. The position of the coracoid is still uncertain, and in fact its
clear association in the pectoral girdle of these species is still a
question. It seems to be constant in the European (186, 251) species and
is usually represented by a small rounded plate of bone, which in life no
doubt had a large amount of cartilage to form its borders. A cleithrum
(285) has been ascribed to one of the Linton, Ohio, species (plate 15,
fig. 3) by Jaekel (347), but this needs confirmation. An osseous scapula
is usually present, resembling the scapula of modern salamanders, in that
it was largely embedded in cartilage. The position of the pectoral girdle
is largely a matter of doubt, especially for the American species. After
death and before fossilization the girdle was always moved by post-mortem
shifting, so that its exact relation to the ribs and vertebral column
is still in doubt. Credner (186) has restored the pectoral girdle close
behind the head, which would cause an amount of rigidity in the body which
probably did not exist.
(_o_) The _arm_ consists of the humerus, radius, ulna, and 4 digits.
The characters of the arm-bones are such as is constant among primitive
animals and developing mammals. The osseous portion is perichondral.
Epiphyses are totally lacking and it is doubtful if the endochondrium was
at all ossified. The digits are often terminated by ungual phalanges,
although usually the terminal phalanx was merely embedded in the web of
the foot; and among the terrestrial forms a claw was well developed. An
osseous carpus is not known in the species from the Coal Measures. Its
impression indicates a broad hand, well adapted for swimming.
(p) The _pelvic girdle_ consists uniformly (462) of the ilium and
ischium. A small rounded pubis is present in some of the later forms of
Amphibia; it is, however, totally absent from the Coal Measures species.
The condition of the pelvis is paralleled by the partially grown pelvis
of mammalian embryos in which the elements ossify in the order of ilium,
ischium, and pubis. The ilium is always the larger of the elements. It
supported or was attached to the sacral rib by means of a ligamentous
union. The ischium did not ossify completely until the animal was nearly
mature. The union between the elements of the pelvis was probably of a
loose, membranous sort or else the whole mass was embedded in cartilage;
of the two hypotheses the former is the more probable.
The pubis is indicated as a calcified quadrangular plate in a specimen of
_Amphibamus grandiceps_ Cope (478) from the Mazon Creek shales, and it is
present as a rounded osseous element among some of the Permian forms.
(_q_) The _leg_ (fig. 21, B) is composed of the femur, tibia, fibula,
and 5 digits. The tarsus is usually cartilaginous, a single osseous
tarsus (483, 484) being known (plate 23, fig. 1) from America. The distal
phalanges may or may not be clawed, depending on the habits of life of the
animal. The elements of the leg are ossified in a similar manner to those
of the arm.
(_r_) The _ventral scutellation_ (fig. 9), so commonly present among
all groups of Amphibia in the Coal Measures, consists of a series of
ossifications or calcifications in the myocommata. Among modern amphibians
they occur as thin perpendicular planes of connective-tissue which are
sometimes cartilaginous, especially in _Necturus_, regarded by Wilder
(Memoirs of the Boston Society of Natural History, vol. V, No. 9, p.
400, fig. 6, 1903) and by Wiedersheim (605, p. 58) as a homologue or
predecessor of the sternum, although Wiedersheim says:
"The sternum appears for the first time in Amphibians in the form of
a small variously shaped plate of cartilage situated in the middle
line of the chest. It arises as a paired cartilaginous plate in the
inscriptiones tendineæ of the rectus abdominis muscle, and therefore
may be looked upon as corresponding to a pair of 'abdominal ribs.'
Such cartilaginous abdominal ribs must have been present in greater
numbers in the ancestors of existing Urodeles."
This supposition is fully sustained by the anatomy of the Branchiosauria
(459), which must be looked upon as the actual ancestors of the Caudata.
Wilder says of these structures in _Necturus_ (_op. cit._, p. 400):
"The several cartilaginous rudiments which represent this part
(_i.e._, sternum) in _Necturus_ are somewhat difficult of detection
and thus entirely escaped the attention of the earlier investigators.
They consist of a number of thin cartilages found in several
successive myocommata of the pectoral region and confined mainly to
the area covered by the overlapping epicoracoids."
The homologue of the _ventral scutellæ_ is found in plesiosaurs,
crocodiles, _Sphenodon_, and other reptiles in the "abdominal ribs," and
the same myocommatous ossifications undoubtedly go to the formation of the
chelonian plastron. What the causes were which produced the development
of the ventral scutellæ to such a high degree among the primitive land
vertebrates is uncertain, but they are certainly more highly developed
among the primitive reptiles and amphibians than among the later members
of those classes. Among the Amphibia of the Coal Measures they attained,
in some forms, a high degree of development and differentiation. They are
present in all families so far known, except the Tuditanidæ, in which
the myocommata may have been cartilaginous. The Sauropleuridæ present
the highest development of these structures among the American forms, in
which the scutes are large and osseous. Among the Branchiosauria they
are calcified or partially ossified and are always arranged _en chevron_
on the belly, chest, arms, and throat, their arrangement and direction
of the _chevron_ being modified according to the myomeres of the various
regions. The ventral scutellæ of the European Branchiosauria are figured
and described fully by Credner (192, p. 21, figs. 4 to 11).
[Illustration: Fig. 9.--Ventral scutellæ of _Micrerpeton caudatum_, a Coal
Measures salamander from Mazon Creek. × 5. _f_, femur; _h_, humerus; _ls_,
lines of scutes; _v_, vertebral column.]
(_s_) _Scales_ (fig. 10 and plate 24, figs. 2 and 3) are present on the
body of (462, 485) several species. It is a matter of regret that their
preservation is so imperfect that nothing can be found out as to their
structure. The Linton species, which possess scales, are, of course,
carbonized and hence impracticable for microscopic study, and in the
Mazon Creek species of _Amphibamus_ and _Micrerpeton_ the scales have
been replaced by kaolin. The bodies of two species (_Cercariomorphus
parvisquamis_ and _Ichthyerpeton squamosum_) of the Linton Coal Measures
Amphibia were completely scaled. The scales in the Branchiosauria (462),
so far as they have been observed, are slightly imbricated; rounded, with
concentric markings after the manner of the modern cyprinoid fish-scale.
They are extremely minute, and whether or not they covered the entire body
of the animal is unknown. On the body of _Cercariomorphus_ the scales
have the appearance of being tubercular without imbrication, and they
apparently covered the entire bodily surface of the animal.
[Illustration: Fig. 10.--Horny armor of back of _Hylonomus_. _a_,
imbricated scales; _b_, horny plates; _c_, horny spines or tubercles; _d_,
small imbricated scales. (After Dawson, based on a photograph.)]
Among the Paleozoic Amphibia from Nova Scotia as described by Dawson and
Owen (193, 201, 485) scales are well developed and frequent, although the
details as to their occurrence on the bodies of the animals are still
unknown, since the Nova Scotian species are all based on very fragmentary
remains. Dawson (208, p. 34) has given a detailed discussion of the
discovery and anatomy of the various types of scales possessed by the
species from the Coal Measures of Nova Scotia. Suffice it to say here that
none of the scales appear to be bony, but have a cuticular appearance
with concentric markings. Some of them are tubercular, and Dawson thought
that a few specimens indicated that some of the species possessed scaly
lappets and a dorsal nuchal fringe of scaly skin along the back. He has
indicated these facts in his restorations of the forms. The scales were
all carbonized and burned readily with a strong flame. A section of the
scale shows a thick upper corium with a vascular body (208, pl. IV, fig.
29) much like a fish-scale. Fragments of the skin were also preserved with
the scales. Dawson says of the skin:
"One of my specimens is a flattened portion of cuticle two and a
quarter inches in length. The greater part of the surface is smooth
and shining to the naked eye, and under the microscope shows only a
minute granulation. A limited portion of the upper and, I suppose,
anterior part is covered with imbricated scales, which must have been
membranous or horny, and generally have a small spot or pore near the
outer margin, some having in addition smaller scales or points on
their surfaces" (208, pl. IV, figs. 22 and 25).
(_t_) _Muscle_ tissue (fig. 21) is preserved in a single specimen,
previously described by the writer (464, p. 17, pl. 7, fig. 1). The
carbonized muscles show a myomeric arrangement and the portions preserved
probably represent one of the recti muscles of the abdominal wall.
(_u_) The _lateral-line system_ in the Coal Measures Amphibia will be
best understood from a comparative review of the occurrence of these
organs among all extinct Amphibia. Since all the orders of Amphibia are
represented in the Coal Measures, such a review will not be out of place
here.
The preservation of the lateral-line system among ancient Amphibia is due
to the fact that the skull of many forms (especially the later and larger)
are grooved and marked by a regular series of furrows and pits, in which
the sense-organs of the lateral-line system were contained (see fig. 6),
as well as by the preservation of a series of clearly marked scales on
the sides of the tails and bodies of others. The grooves are never arched
over as in the Macropetalichthyidæ, where "in favorable specimens each is
shown to be covered by a delicate roof perforated by two lines of minute
openings" (Dean, N. Y. Acad. Sci. Mem., vol. II, pl. III, p. 115). They
are always widely opened canals, either with perfectly smooth bottoms
and sides or roughened with large pits, or even becoming a series of
well-marked pits. An attempt has been made (458) to homologize the organs
with those of fishes.
The nomenclature adopted here for the canals does not depart from that
used by Allis for _Amia_ (Journ. of Morphology, vol. II, 1889). The
supraorbital and infraorbital canals are readily correlated with those of
the same name in fishes, where they are very clearly marked. The anterior
commissure is also homologous with that of the fishes, as is also the
canal here called the "antorbital commissure." The others are not so
readily homologized. The upper canal (see fig. 6) in the posterior part
of the cranium is here designated the _temporal canal_. It is, however,
clearly a part of the infraorbital of the fishes. Its relations in the
Stegocephala are such that a new name is deemed necessary. The _jugal
canal_ is, I believe, a new formation in Amphibia. The transverse canal of
the amphibian skull is homologous with the "occipital cross-commissure."
The figure (see fig. 6) is a composite picture of the lateral-line system
of the higher or truly stegocephalous Amphibia. The outline of the skull
is based on that of _Eryops_. All of the canals do not exist on any one
skull or in any one order, but all are found somewhere in the group.
[Illustration: Fig. 11.
A. Skull of _Eoserpeton tenuicorne_ Cope, showing arrangement of
cranial elements. × 2. _fr_, frontal; _j_, jugal; _mx_, maxilla;
_n_, nasal; _or_, orbit; _par_, parietal; _pof_, postfrontal;
_pmx_, premaxilla; _po_, postorbital; _pp_, postparietal; _qj_,
quadratojugal; _sq_, squamosal; _spt_, supratemporal; _tab_,
tabulare.
B. Outline of skull of _Ceraterpeton galvani_ Huxley from the
Carboniferous of England. Heavy broken lines show the
distribution of lateral-line canals. × 1. (After Andrews.) _fr_,
frontal; _par_, parietal; _or_, orbit; _po_, postorbital; _pp_,
postparietal; _spt_, supratemporal; _tab_, tabulare.
]
The canals have been described in all known orders of fossil Amphibia
and the system is found likewise in all the living orders, including the
Gymnophiona, which have "a strong line of lateral sense-organs" (Gadow).
In the Branchiosauria, the earliest of the true Amphibia (Euamphibia)
and ancestral to the modern Caudata, the lateral-line system is known
on the tails of two genera (462, 478) from the Mazon Creek, Illinois,
shales--_Micrerpeton_ and _Eumicrerpeton_. The system as there defined
has been fully discussed in the description of the anatomical details of
the species, to which reference may be made for further data (pp. 52-60).
Suffice it to say here that the system of sense-organs there preserved
is identical with that of the larval _Necturus_; the lines arising as a
_median_ from the tip of the tail and a _dorsal_ springing from the median
at a distance of a few millimeters from the tip of the tail. The lines are
more evident on account of the fact that the lateral-line sense-organs
were located under specialized pigmented scales. The significance of the
close similarity between the arrangement of the lateral-line systems on
the tail of Necturus, _Micrerpeton_, and _Eumicrerpeton_ is doubtless of
genetic (459) importance, indicating the origin of the caudate Amphibia
from the Branchiosauria by a degenerative or recessive evolution in other
structural characters. This system of sense-organs has been described in
no other branchiosaurian.
The Microsauria (458) are exceedingly interesting in possessing a very
peculiar type of lateral-line system. It is known in a few forms and in
one specimen especially well (_Erpetosaurus tabulatus_) (fig. 22, G). In
this species, which is represented by a single imperfect skull, there are
evidences of a nearly complete lateral-line system of canals and pits.
The occipital cross-commissure is represented on the posterior border
of the skull by a row of elongate pits such as Andrews described for
_Ceraterpeton_ (8). I fail to find in American species the pores described
by Andrews. The temporal canal forms with the jugal canal a complete ring,
much as it is in _Trematosaurus_, only in _Erpetosaurus tabulatus_ the
temporal canal does not touch the tabulare. I think there are indications
of a connection of the temporal canal with the supraorbital. The temporal
canal cuts the supratemporal, the squamosal, and jugal. The jugal canal
lies for the most part on the supratemporal and quadratojugal, and joins
the infraorbital on the jugal. A portion only of the infraorbital canal
is preserved. There is also a portion of the supraorbital canal. It seems
not to be connected with the temporal canal, although there is a possible
indication of this connection. The supraorbital crosses the frontal,
prefrontal, and a part of the nasal. The squamosal element is peculiar
in _Erpetosaurus tabulatus_ in that it is excluded from the parietal by
the extension of the tabulare and postorbital. This condition is found in
several other species of the Microsauria. It will be noticed that with the
changed condition of the squamosal the temporal canal has changed also,
and this is further proof of the close connection between the cranial
elements and the lateral-line canals, as Allis has maintained for _Amia_.
(See in this connection C. J. Herrick, Journ. Comp. Neurol., vol. II, p.
224, 1901.)
The Diplocaulia, an amphibian order allied to the Branchiosauria (477)
and through them to the Caudata, have the lateral-line system apparently
well-developed. The skulls are always crushed flat, so that the canals
are nearly obliterated. On the mandible, however, the canals are clearly
distinct and apparently run the entire course around the mandibular rami.
On a well-preserved skull of _Diplocaulus magnicornis_ Cope there are
indications of three lateral-line canals (477, pl. 1). The infraorbital
is clearly marked as a well-defined groove just below the orbit. The
supraorbital is indicated only for a short distance, and there are
indications of the temporal canal. The operculo-mandibular canal has
its course, for the most part, near the middle of the rami, but as it
approaches the posterior angle of the mandible it suddenly changes its
course and drops down to the lower edge, only to rise again and to come
out strongly marked near the median plane on the posterior angle of the
mandible.
The Temnospondylia, as represented by _Eryops_, _Cricotus_, and
_Archegosaurus_, possess well-developed lateral-line canals (458). H.
von Meyer (428) many years ago made out the course of the canals in
_Archegosaurus_. The greater part of the following description is based
on _Eryops megacephalus_ Cope from the Texas Permian. The entire surface
of the cranial elements in _Eryops_, as in other of the Stegocephala
(458), is covered with coarse pits. The fossæ are present even in
the bottoms of the grooves which represent the lateral-line system,
and are more marked in the members of the Temnospondylia than in the
Stereospondylia.
The occipital cross-commissure occurs in a well-developed form in
_Eryops_. It is short and ends abruptly within the limits of the tabulare.
Its ends are occupied by large pits. The commissure, as in _Amia_, grooves
the postparietal and the tabulare elements. There is no evidence of an
anterior commissure. I think there is evidence of a temporal canal on the
left side of the skull, but am not sure. The jugal and infraorbital canals
are well developed and strongly connected. The jugal canal starts far back
on the supratemporal, and after curving around over the quadratojugal
joins the infraorbital, or rather becomes a part of that canal, somewhere
on the jugal. There is nothing unusual in the infraorbital. The antorbital
commissure is well developed. It is longer and better developed than in
any other known form. The supraorbital canal starts in the region of the
orbit, and after curving downwards to meet the antorbital commissure, ends
abruptly anterior to the nostril. There are faint traces of a lateral-line
canal, the operculo-mandibular, on a poorly preserved mandible of
_Eryops_. It does not differ greatly from that described below for
_Anaschisma_.
Although _Archegosaurus_ has been known for more than a century, we
have had no adequate discussion of the manner of occurrence of the
lateral-line canals. Burmeister (80) gave a figure of the canals as he
thought they occurred on the cranium, but H. von Meyer (428) states that
the representation is inaccurate, and they seem to be based largely on
_Trematosaurus_.
The lateral-line canals occur in well-developed form on the skulls of
the Stereospondylia. The sutures between the elements of the skull are
usually clearly marked by smooth, narrow grooves. The lateral-line canals
can always be distinguished from the sutural grooves by the shape of the
bottom, being =U=-shaped in the former and =V=-shaped in the latter. The
lateral-line canals also at times have their bottoms roughened by pits
occurring in them; the sutural grooves always have smooth bottoms. The
lateral-line canals are usually rather shallow and sometimes broad, with
the edges of the grooves more or less perpendicular, but in _Metoposaurus_
the canals are deep and the borders are sharply incised.
The temporal canals in _Anaschisma_ from the Triassic (49) of Wyoming
are represented by broken furrows. The portions preserved exhibit the
usual downward tendency to unite with the infraorbital on the postorbital
element. In its course forward from the epiotic the temporal canal cuts
the squamosal. The supraorbital canal has an unusually deviating course
in _Anaschisma_, but aside from the minor twists and curves it does not
differ essentially from the same canal in other forms. It ends abruptly
on the anterior end of the muzzle. In its course it gives off the vestige
of an antorbital commissure which tends to join a vestige from the
infraorbital canal. The jugal canal begins broadly at the very posterior
edge of the skull as though it were continued, as it undoubtedly was, to
the body of the animal. In its course forward it joins the infraorbital
canal on the jugal. The course of the infraorbital is not unusual in
any respect. There is no anterior commissure on the skull, nor is the
occipital cross-commissure developed on either skull of the genus at hand.
There are distinct evidences of an operculo-mandibular lateral-line canal
on the mandibles. The canal enters the mandible on the surangular and
passes forward around the mandible as described for _Diplocaulus_ (477).
Other members of the Stereospondylia, such as _Mastodonsaurus_,
_Metoposaurus_, and _Trematosaurus_ possess well-developed lateral-line
canals, but the above description fits, in a general way, the condition in
all genera; and for our present purposes that will suffice.
CHAPTER V.
THE AMPHIBIA OF THE DEVONIAN AND MISSISSIPPIAN OF NORTH AMERICA.
Evidences of the earliest land vertebrates are exceedingly scanty in the
strata between the close of the Silurian and the opening of the Coal
Measures, being represented solely by footprints. In the Devonian our
knowledge of the group is confined to a single footprint, and in the
Mississippian to series of footprints from several localities. These
have been described by Lea (371), Rogers (Geology of Pennsylvania, pt.
II, 1856, p. 831), Barrell (21), Dawson (223), and Branson (50). The
last-named author has described a new species from the Mississippian
of Giles County, Virginia. His description of the footprints, with a
photograph of one of the series, are published herewith (plate 18, fig.
3). Branson (50) has given a _résumé_ of the knowledge of Mississippian
Amphibia in North America.
=Thinopus antiquus Marsh, 1896.=
Marsh, Am. Jour. Science, II, p. 374, Nov. 1896, with figure.
Type: Specimen No. 784, Yale University Museum.
Horizon: Near top of Chemung, in the upper Devonian.
[The] "specimen shows one vertebrate footprint in fair preservation,
and with it part of another of the same series. These impressions are
of much interest, both on account of their geological age and the size
and character of the footprints themselves. The one best preserved
[fig. 12] is nearly 4 inches in length, 2.25 inches in width, and was
apparently made by the left hind foot. On the inner side in front of
the heel, a portion of the margin is split off, and this may have
contained the imprint of another toe. The other footprint was a short
distance in front, but only the posterior portion is now preserved in
the present specimen. It is probably the imprint of the forefoot.
"The specimen [plate 18, fig. 4] ... was ... found in the town of
Pleasant, one mile south of the Allegheny River, Warren County,
Pennsylvania, by Dr Charles E. Beecher, who presented it to Yale
Museum, where it still remains.
"The geological horizon is near the top of the Chemung in the
upper Devonian. In the same beds are ripple marks, mud cracks,
and impressions of rain drops, indicating shallow water and shore
deposits. Land plants are found in the same general horizon. Marine
molluscs also occur, and one characteristic form (_Nuculana_) is
preserved in the footprint slab" (Marsh).
[Illustration: Fig. 12. Copy of Marsh's drawing of footprint of _Thinopus
antiquus_, from the Devonian of Pennsylvania. × 1/3.]
This still remains after nearly 20 years the only evidence of
air-breathing vertebrates in the Devonian of the world.
=Dromopus aduncus Branson.=
Branson, Jour. Geol., XVIII, No. 4, pp. 356-358, fig. 1, 1910.
Type and other specimens in Oberlin College Museum.
Horizon and type locality: Near the bottom of the Hinton formation in
Giles County, Virginia. (Plate 18, fig. 3.)
The following description of the shales and footprints are from Dr.
Branson's paper cited above:
"The Hinton shales, like the Mauch Chunk, seem to have been subaerial
in origin and are made up for the most part of variegated shales
interbedded with thin layers of argillaceous, fine-grained sandstone.
The footprints occur in fine-grained sandstone, and remains of land
plants are not uncommon in the same beds.
"Twenty-two footprints made by one animal walking in a straight
course were collected in a slab. They give the impression of having
been made by a bipedal animal for part of the distance, but after the
fourth print of the right foot impressions of the forefeet appear. The
hindfeet had 5 digits, the middle digit being longest and the 2 inside
of it being only slightly shorter and lying close together. Their
outer ends were slender and flexible and usually curved inward toward
the middle toe. The 2 outer digits formed wide angles with the middle
one and were shorter than the inner ones. The second toe was webbed to
within 8 mm. of the tip, the third toe to within 23 mm. of the tip.
The impression of the web is well preserved in only one impression of
the hindfoot.
"The forefeet had 4 digits. The 3 inner digits were subequal in
length, the 2 inner being more flexible and incurved near the ends.
The outer digit is two-thirds as long as the second. The webbing
extends about half the length of the digits. The heel impression is
broader than that of the hindfoot.
"Measurements of _Dromopus aduncus_ Branson.
Tip of toe to tip of toe in first prints 21 cm.
After appearance of forefeet the impressions are the following
distances apart: 165 mm., 40 mm., 85 mm., 70 mm., 80 mm., 40 mm.,
150 mm., then back to 20 and 21 cm.
mm.
Length of hindfeet 60
Width of hindfeet 20 to 25
Length of forefeet 45"
CHAPTER VI.
A HISTORY OF THE CLASSIFICATION OF THE AMPHIBIA, WITH ESPECIAL REFERENCE
TO THE SPECIES FROM THE COAL MEASURES.
It has been necessary, in the course of the present study, to review
thoroughly the classifications which have been proposed for the group. A
classification of some sort is necessary for the proper grouping of the
species which have been recovered from the Coal Measures deposits of this
continent, and my reason for publishing this relatively dry material is
that the classifications formerly proposed (469), as well as the one here
given, may have a proper historical background.
The review of the proposed systems of classification has been much
facilitated by the discovery, in the University of Chicago, of some
notes by the late Dr. George Baur on the "Stegocephali." The notes were
not discovered until after the literature had been pretty thoroughly
covered, and it was a source of some gratification, on comparing notes
with those of Dr. Baur, to find but few omissions. Whether Dr. Baur had
ever contemplated a work on the Stegocephala or not I have been unable to
learn, but it is certain that he carefully and laboriously went through
the literature on the subject and copied by hand the classifications of
each author from 1842 to 1895, together with other notes of interest on
the structure, distribution, and phylogeny, including many tracings. The
classifications given below are taken, in part, from his notes, although
all references have been verified with the original sources.
The first attempt to combine in classification the knowledge of the
extinct and recent amphibians was made by Johannes Jacob von Tschudi in
1839 (574). Previous to that time Goldfuss (295) and von Meyer (418) had
described various species of salamanders and frogs from the Tertiary
deposits of Switzerland, and these Tschudi considered in his following
classification:
A. Ranæ.
_a._ _Hylæ._
_b._ _Cystignathi._
_c._ _Ranæ._
_d._ _Ceratophrydes._
_e._ _Bombinatores._
_f._ _Bufones._
_g._ _Pipæ._
B. Cœciliæ.
_a._ _Cœciliæ._
C. Salamandrinæ.
_a._ _Pleurodeles._
_b._ _Salamandræ._
_c._ _Tritones._
_d._ _Tritonides._
D. Protoideæ.
Although the remains of _Mastodonsaurus_ had been known and widely
commented on for several years before Tschudi proposed this scheme, he
does not include this genus in his classification of the Amphibia, for
the reason that for nearly a quarter of a century after the discovery of
the labyrinthodonts they were regarded as reptiles, even so eminent an
authority as von Meyer (423) including them in his "System der fossilen
Saurier." The view that the labyrinthodonts were reptiles was at times
disputed, but no one seemed to pay any attention to the argument of
Quenstedt in 1850 that "Die Mastodonsaurier im grünen Keupersandstein
Würtemburgs sind Batrachier" (527), nor to the contention of Vogt (581) in
1854 that "Archegosaurus und alle Labyrinthodonten sind Amphibien, nicht
Reptilien."
In 1842 von Meyer (420) proposed to include all the early forms allied
to the _Mastodonsaurus_ in the "Labyrinthodontes." His definition of the
group follows:
Labyrinthodontes: Saurier deren Zahn-Struktur jener ähnlich ist, welche in
den nach prismatischer Art gebauten Säugethier-Zähnen wahrgenommen wird,
u.s.w.
I. _Mastodonsaurus Jaeger._ (_Salamandroides_ Jaeger,
_Batrachosaurus_ Fitzinger, _Labyrinthodon_ Owen.)
_M. Jaegeri_ Meyer.
II. _Capitosaurus_ Münster.
_C. arenaceus_ Münst.
_C. robustus_ Meyer.
III. _Metopias_ Meyer.
_M. diagnosticus_ Meyer.
Three years later von Meyer (423) proposed his "System der fossilen
Saurier," where the extinct Amphibia are treated as follows:
Labyrinthodontes.
1. Prosthopthalmi (Augen-höhlen in der vordern Hälfte der
Schädel-Länge) _Metopias_ Meyer Keuper.
2. Mesopthalmi (Augen-höhlen in der mitte der Schädel)
_Mastodonsaurus_ Jaeger Keuper, Muschelkalk.
3. Opisthopthalmi (Augen-höhlen in der hintern Hälfte der
Schädel-Länge) _Capitosaurus_ Münster Keuper.
4. Labyrinthodonten ungewisser Stellung.
_Labyrinthodon_ Owen Keuper.
_Xestorrhytias_ Meyer Muschelkalk.
_Odontosaurus_ Meyer Bunter Sandstein.
_Trematosaurus_ Braun Bunter Sandstein.
No other classification was proposed for the extinct Amphibia for 15
years, when Owen (512) in 1859 proposed the new order Ganocephala and
retained von Meyer's Labyrinthodontes under Labyrinthodontia. Owen's
classification is as follows:
Class--Reptilia.
Order I. Ganocephala.
Genera: _Archegosaurus_, _Dendrerpeton_, _Raniceps_.
Order II. Labyrinthodontia.
Genera: _Mastodonsaurus_, _Anisopus_, _Trematosaurus_, _Metopias_,
_Capitosaurus_, _Zygosaurus_, _Xestorrhytias_.
In his Paleontology published in 1861, Owen gives the same classification,
but adds new genera.
Huxley in 1863 (332) did not accept Owen's Ganocephala, but instead
proposed the following:
Labyrinthodontia.
A. Archegosauria. _Archegosaurus_, _Pholidogaster_.
B. Mastodonsauria. _Mastodonsaurus_, _Labyrinthodon_, _Capitosaurus_,
_Trematosaurus_.
In the same year Dawson proposed (208) the term Microsauria to include
the genera _Hylonomus_, _Dendrerpeton_, and _Hylerpeton_, all known from
the Carboniferous rocks of Nova Scotia. Two years later Cope proposed
the new order Xenorhachia (105) for the reception of the form _Amphibamus
grandiceps_ from the Coal Measures of Illinois. He gave as the characters
of this order cartilaginous vertebræ and the absence of ribs.
In 1866 Owen proposed (516) the most elaborate and comprehensive scheme of
classification which had thus far been offered. His classification is as
follows:
Subclass Dipnoa.
Order Ganocephala (extinct). Genera: _Archegosaurus_,
_Dendrerpeton_, etc.
Order Labyrinthodontia. Genera: _Labyrinthodon_, _Rhombopholis_, etc.
Order Batrachia.
Suborder Ophiomorpha. Family: Cœcilidæ.
Suborder Ichthyomorpha. Family: Proteidæ, Salamandridæ.
Suborder Theriomorpha (Anura).
Family 1. _Aglossa._
Family 2. _Ranidæ._
Family 3. _Hylidæ._
Family 4. _Bufonidæ._
Haeckel the same year proposed (312) an entirely different scheme of
classification nd in some respects more acceptable than Owen's. Haeckel's
classification is as follows:
Class Amphibia.
Subclass I. Phractamphibia.
Ordnung i. Ganocephala.
Genera: _Archegosaurus_, _Dendrerpeton_, _Raniceps_.
Ordnung 2. Labyrinthodonta.
Genera: _Baphetes_, _Zygosaurus_, _Mastodonsaurus_,
_Trematosaurus_, _Capitosaurus_.
Ordnung 3. Peromela.
Subclass II. Lissamphibia.
Ordnung i. Socobranchia.
Genera: _Siren_, _Proteus_, _Menobranchus_, etc.
Ordnung 2. Sozura (Caudata).
Genera: _Cryptobranchus_, _Triton_, _Salamandra_.
Ordnung 3. Anura (Ecaudata).
Families: _Aglossa_, _Bufonidæ_, _Ranidæ_.
This classification is further elaborated in the edition of 1895.
Cope in 1868 proposed (110) the scheme of classification which was in
use for some time, although it has since suffered some change. His
classification follows:
Batrachia.
Order 1. Trachystoma.
Order 2. Proteida.
Order 3. Urodela.
Order 4. Gymnophiona.
Order 5. Stegocephali.
Suborder Xenorhachia.
_Amphibamus grandiceps_ Cope.
Suborder Microsauria.
Genera: _Pelion_ Wyman, _Hylonomus_ Dawson, _Pariostegus_ Cope,
_Dendrerpeton_ Owen, _Hylerpeton_ Owen, _Brachydectes_ Cope,
_Sauropleura_ Cope, _Œstocephalus_ Cope, _Molgophis_ Cope.
Suborder Labyrinthodontia.
Genera: _Dictyocephalus_ Leidy, _Centemodon_ Lea, _Baphetes_ Owen,
_Eupelor_ Cope.
Huxley in 1869 proposed (335) the following classification, which does not
differ essentially from that proposed in 1863:
Amphibia.
Order 1. Urodela.
Order 2. Batrachia.
Order 3. Gymnophiona.
Order 4. Labyrinthodontia.
Suborder Archegosauria.
Suborder Mastodonsauria.
The next classification of the extinct Amphibia of any importance was
that devised by the committee (450) for the British Association in 1874.
This committee was formed of Huxley, Harkness, Henry Woodward, Thompson,
and Brigg, with Miall as secretary. This classification is, however,
too cumbersome and has never come into general use, and indeed none but
English authors have paid it a great deal of attention, although the
contribution was a valuable one. The group Aistopoda, which was the ninth
group proposed by the committee, has generally been accepted as the group
represented by the snake-like forms. The committee's classification
follows:
Labyrinthodontia.
Section I. Euglypta.
Genera: _Mastodonsaurus_, Jaeger; _Capitosaurus_, Münst.; _Pachygonia_,
Huxley; _Trematosaurus_, Braun; _Gonioglyptus_, Huxley; _Metopias_,
von Meyer; _Labyrinthodon_, Owen; _Diadetognathus_, Miall;
_Dasyceps_, Huxley; _Anthracosaurus_, Huxley.
Section II. Brachyopina.
Genera: _Brachyops_, Owen; _Micropholis_, Huxley; _Rhinosaurus_,
Waldheim; _Bothriceps_, Huxley.
Section III. Chauliodonta.
Genera: _Loxomma_, Huxley; _Zygosaurus_, Eich.; _Melosaurus_, Meyer.
Section IV. Arthroödonta.
Genera: _Batrachiderpeton_, Hancock and Atthey; _Pteroplax_, Hancock
and Atthey.
Section V. An uncharacterized group.
Genera: _Pholidogaster_, Huxley; _Ichthyerpeton_, Huxley;
_Pholiderpeton_, Huxley.
Section VI. Archegosauria, von Meyer.
Genera: _Archegosaurus_, Goldfuss.
Section VII. Heleothrepta.
Genera: _Lepterpeton_, Huxley.
Section VIII. Nectridea.
Genera: _Urocordylus_, Huxley; _Keraterpeton_, Huxley.
Section IX. Aistopoda.
Genera: _Ophiderpeton_, Huxley; _Dolichosoma_, Huxley.
Section X. Microsauria, Dawson.
Genera: _Dendrerpeton_, Owen; _Hylonomus_, Dawson; _Hylerpeton_, Owen.
The schemes of classification used for the next 10 years did not depart in
any appreciable degree from those already given.
In 1875 Cope, in his Check-list of North American Batrachia and
Reptilia (120), with a systematic list of the higher groups, published
the following classification as being "adopted provisionally by the
Smithsonian Institution":
Class Batrachia.
Order Anura. (Anura, Duméril; Salientia, Merrem, Gray.)
Raniformia. (Raniformia, Cope, Nat. Hist. Rev., V, 114, 1865.)
Families: _Ranidæ_, _Colostheidæ_.
Firmisternia. (Bufonoid Raniformia, Cope, Jour. Acad. Nat. Sci.,
Philadelphia, n.s., VI, 190, 1867.)
Families: _Dendrobatidæ_, _Phryniscidæ_, _Engystomidæ_,
_Breviceptidæ_.
Gastrechmia. (Gastrechmia, Cope, Jour. Acad. Nat. Sci.,
Philadelphia, n.s., VI, 198, 1867.)
Family: Hemisidæ.
Bufoniformia. (Bufoniformia, Duméril et Bibron, _partim_; Cope,
_partim_.)
Families: _Rhinophrynidæ_, _Bufonidæ_, _Batrachophrynidæ_.
Aglossa.
Family: _Pipidæ._
Odontaglossa.
Family: _Dactylethridæ._
Arcifera. (Arcifera, Cope, N. H. Rev., V, 104, 1865.)
Families: _Cystignathidæ_, _Hemiphractidæ_, _Hylidæ_,
_Scaphiopidæ_, _Pelodytidæ_, _Asterophrydidæ_, _Discoglossidæ_.
Order Stegocephali. (Stegocephali Cope, Proc. Acad. Nat. Sci.,
Philadelphia, 1868, 209.)
Labyrinthodontia.
Families: _Baphetidæ_ Cope, _Anthracosauridæ_ Cope.
Ganocephala.
Family: _Colosteidæ_ Cope.
Microsauria.
Families: _Phlegethontiidæ_ Cope, _Molgophidæ_ Cope, _Ptyoniidæ_
Cope, _Tuditanidæ_ Cope,
_Peliontidæ_ Cope.
Order Gymnophiona. (Gymnophiona Müller.)
Family: _Cœciliidæ_ Gray, 1850.
Order Urodela.
Families: _Pleurodelidæ_ Gray, 1858; _Salamandridæ_: Gray, 1858;
_Hynobiidæ_ Cope, 1866; _Desmognathidæ_ Cope, 1866; Thoriidæ
Cope, 1869; _Plethodontidæ_ Cope, 1866; _Amblystomidæ_ Cope,
1866; _Menopomidæ_ (_Protonopsidæ_ Gray, 1850), _Amphiumidæ_
Cope, 1866; _Cocytinidæ_ Cope.
Order Proteida.
Family: _Proteidæ_ Gray, 1850.
Order Trachystomata.
Family: _Sirenidæ_ Gray, 1850.
In 1885 Cope proposed 2 new orders, which he arranges with the other
orders already known, as follows:
{ Order I. Rachitomi. Order V. Urodela.
Batrachia. { Order II. Embolomeri. Order VI. Trachystomata.
{ Order III. Stegocephali. Order VII. Anura.
{ Order IV. Proteida.
The new order Rachitomi was to include forms like Eryops and the new order
Embolomeri was to include forms like Cricotus; the other orders were as
they had been given before.
Zittel in 1888 proposed (642) the next classification of any note in his
"Handbuch der Paleontologie," where it stands as follows:
Classe Amphibia.
Ordnung 1. Stegocephali.
Unterordnung 1. Lepospondyli.
Familie 1. _Branchiosauridæ_ Fritsch.
" 2. _Microsauria_ Dawson.
" 3. _Aistopoda_ Miall.
Unterordnung 2. Temnospondyli.
Genera: _Archegosaurus_, _Eryops_, etc.
Unterordnung 3. Stereospondyli.
Familie 1. _Gastrolepidoti_.
" 2. _Labyrinthodonta_.
Ordnung 2. Cœciliæ.
Ordnung 3. Urodela.
Unterordnung 1. Ichthyoidea.
Familie 1. _Phanerobranchia_.
" 2. _Cryptobranchia_.
Unterordnung 2. Salamandrina.
Ordnung 4. Anura.
Unterordnung 1. Phaneroglossa.
Familie 1. _Ranidæ_.
" 2. _Bufonidæ_.
" 3. _Cystignathidæ_ Cope.
" 4. _Pelobatidæ_ Boul.
" 5. _Discoglossidæ_ Cope.
" 6. _Palæobatrachidæ_ Cope.
Lydekker (393) in the next year proposed a system of classification which
did not depart widely from that proposed (450) by the committee of the
British Association for 1874. Lydekker's classification is as follows:
Class Amphibia.
Order I. Labyrinthodontia.
Suborder 1. Branchiosauria.
Family _Protritonidæ_.
" _Apateonidæ_.
Suborder 2. Aistopoda.
Family _Dolichosomatidæ_.
Suborder 3. Microsauria.
Family _Urocordylidæ_.
" _Limnerpetidæ_.
" _Hyloplesionidæ_.
" _Microbrachidæ_.
Suborder 4. Labyrinthodontia vera.
Family _Archegosauridæ_.
" _Diplospondylidæ_.
" _Nyraniidæ_.
" _Dendrerpetidæ_.
" _Anthracosauridæ_.
" _Mastodonsauridæ_.
Uncertain family, _Eosaurus_.
Order II. Apoda.
Order III. Caudata.
Family _Hylæobatrachidæ_.
" _Sirenidæ_.
" _Proteidæ_.
" _Amphiumidæ_.
" _Salamandridæ_.
Order IV. Ecaudata.
Family _Discoglossidæ_.
" _Pelobatidæ_.
" _Palæobatrachidæ_.
" _Cystignathidæ_.
" _Ranidæ_.
In 1890 Döederlein proposed a scheme of classification which is notable on
account of the peculiar relations which it expresses between the groups
relations which, in reality, do not exist. His classification is as
follows:
Class Amphibia.
Ordnung I. Stegocephali.
A. Microsauria.
Unterordnung 1. Branchiosauri.
Genera: _Branchiosaurus_, _Dawsonia_, _Melanerpeton_,
_Pelosaurus_.
Unterordnung 2. Sauromorphi.
Familie 1. _Hylonomidæ_.
" 2. _Nectridæ_.
" 3. _Aistopodidæ_.
B. Ganocephala.
Unterordnung 1. Rhachitomi.
" 2. Embolomeri.
" 3. Labyrinthodontia.
Ordnung II. Urodela.
Ordnung III. Gymnophiona.
Ordnung IV. Anura.
In 1890 Lydekker used the same classification, with minor changes, which
he had used in his Paleontology. Credner, who wrote at about the same time
(193), followed Zittel's classification. Zittel in 1895 merely repeated
his former classification. In 1898 appeared Smith Woodward's Paleontology,
where the following scheme is adopted:
Class Batrachia.
Order I. Stegocephalia. Order II. Gymnophiona.
Suborder 1. Branchiosauria. Order III. Caudata.
" 2. Aistopoda. Order IV. Ecaudata.
" 3. Microsauria.
" 4. Labyrinthodontia.
Hay's Catalogue of Fossil Vertebrata of North America contains the
next scheme for the classification of the Amphibia which pays especial
attention to the extinct forms. His classification is as follows:
Class Batrachia Macartney, 1802.
Order Stegocephali Cope, 1868.
Suborder Microsauria Dawson, 1863.
Family _Protritonidæ_ Lydekker, 1889.
Genera: _Amphibamus_ Cope, _Pelion_ Wym.
Family _Molgophidæ_ Cope, 1875.
Genera: _Phlegethontia_ Cope, _Molgophis_ Cope.
Family _Hylonomidæ_ Fritsch, 1883.
Genera: _Hylonomus_ Dawson, _Smilerpeton_ Dawson, _Hylerpeton_
Owen, _Fritschia_ Dawson; _Brachydectes_ Cope.
Family _Ptyoniidæ_ Cope, 1875.
Genera: _Keraterpeton_ Huxley, _Œstocephalus_ Cope, _Ptyonius_
Cope, _Ctenerpeton_ Cope.
Family _Tuditanidæ_ Cope, 1875.
Genera: _Tuditanus_ Cope, _Cocytinus_ Cope.
Family _Diplocaulidæ_ Cope, 1881.
Genus: _Diplocaulus_ Cope.
Lepospondylous Genera of uncertain position: _Amblyodon_
Dawson, _Hyphasma_ Cope, _Eurythorax_ Cope, _Thyrsidium_
Cope, _Pleuroptyx_ Cope, _Cercariomorphus_ Cope.
Suborder Apœcospondyli Hay, 1902.
Family _Dendrerpetontidæ_ Fritsch, 1889.
Genera: _Dendrerpeton_ Owen, _Baphetes_ Owen, _Platystegos_
Dawson.
Family _Sauropleuridæ_ Hay, 1902.
Genera: _Sauropleura_ Cope, _Leptophractus_ Cope.
Family _Archegosauridæ_.
Genera: _Trimerorhachis_ Cope, _Dissorophus_ Cope.
Family _Cricotidæ_ Cope, 1884.
Genera: _Cricotus_ Cope.
Family _Anthracosauridæ_.
Genus: _Eosaurus_ Marsh.
Family _Eryopidæ_ Cope, 1882.
Genera: _Eryops_ Cope, _Ichthycanthus_ Cope, _Zatrachys_ Cope,
_Anisodexis_ Cope, _Acheloma_ Cope.
Family _Mastodonsauridæ_ Huxley, 1863.
Genera: _Mastodonsaurus_ Jaeger, _Eupelor_ Cope, _Pariostegus_
Cope, _Dictyocephalus_ Leidy.
Order Urodela.
Genera: _Scapherpeton_ Cope, _Hemitrypus_ Cope.
Order Salientia Laurenti, 1768.
Family _Ranidæ_.
Genera: _Rana_ Linné, _Eobatrachus_ Marsh.
This classification given by Hay is only for the forms which occur in
North America.
CHAPTER VII.
CLASSIFICATION OF AMPHIBIA ADOPTED IN THIS WORK, AND A LIST OF THE COAL
MEASURES AMPHIBIA FROM NORTH AMERICA.
A few words of explanation will be necessary for an understanding of the
following classification. The term Amphibia Linné, 1758, is, according
to Stejneger (550), the correct term for the entire group, and this term
is adopted. The term _Stegocephala_, formerly used as a group name for
the entire Carboniferous, Permian, and Triassic Amphibia, regardless of
structure, has been retained as a third subclass. The choice, so far as
priority is concerned, between Labyrinthodontia and Stegocephala, is not
easy. The terms, however, imply different structures. The labyrinthodonts
proper have stereospondylous vertebræ, while the Stegocephala have either
temnospondylous or stereospondylous vertebræ; so the latter term has been
adopted.
The ordinal terms are those which have been used previously as subordinal,
sectional, or family names, with the exception of the new ordinal term
"Diplocaulia" (477). The term Branchiosauria is well-established, and
it is here retained with the definitions previously given. The same may
be said for the Microsauria, although Dawson first (208) regarded it
as a family, though giving the term an ordinal form. The Aistopoda are
not entitled to consideration as a group for reasons which are given
subsequently. The Temnospondylia and the Stereospondylia, the Embolomeri
and the Rachitomi may or may not be good group names, but they have
priority, so far as our knowledge of structure goes. They have been
retained in their original meanings. They have been variously regarded as
sections, superfamilies, groups, and subfamilies.
The following list of species is arranged according to the proposed scheme
of classification:
Class Amphibia Linné, 1758. Devonian to Recent.
Subclass Euamphibia Moodie, 1909. Coal Measures to Recent.
Order Branchiosauria Lydekker, 1889. Coal Measures to Permian.
Family _Branchiosauridæ_ Fritsch, 1879.
_Micrerpeton caudatum_ Moodie, Mazon Creek.
_Eumicrerpeton parvum_ Moodie, Mazon Creek.
_Mazonerpeton longicaudatum_ Moodie, Mazon Creek.
_Mazonerpeton costatum_ Moodie, Mazon Creek.
_(?) Sparodus_ sp. indet. Dawson, Nova Scotia.
Order Caudata Duméril, 1806. Coal Measures to Recent.
Suborder Proteida Cope, 1868. Coal Measures, Eocene, and Recent.
Family _Cocytinidæ_ Cope, 1875.
_Cocytinus gyrinoides_ Cope, Linton, Ohio.
_Erierpeton branchialis_ Moodie, Mazon Creek.
_Hyphasma lævis_ Cope, Linton, Ohio.
Order Diplocaulia Moodie, 1912. Coal Measures to Permian.
Family _Diplocaulidæ_ Cope, 1881.
_Diplocaulus salamandroides_ Cope, Salt Fork, Illinois.
(?) Order Salientia Laurenti, 1768. Coal Measures (?) to Recent.
Family _Peliontidæ_ Cope, 1875.
_Pelion lyelli_ Wyman, Linton, Ohio.
Subclass Lepospondylia Zittel, 1887. Coal Measures.
Order Microsauria Dawson, 1863. Coal Measures.
Family _Hylonomidæ_ Fritsch, 1883.
_Hylonomus latidens_ Dawson, Nova Scotia.
_Hylonomus lyelli_ Dawson, Nova Scotia.
_Hylonomus multidens_ Dawson, Nova Scotia.
_Hylonomus wymani_ Dawson, Nova Scotia.
_Smilerpeton aciedentatum_ Dawson, Nova Scotia.
_Hylerpeton dawsonii_ Owen, Nova Scotia.
_Hylerpeton intermedium_ Dawson, Nova Scotia.
_Hylerpeton longidentatum_ Dawson, Nova Scotia.
_Fritschia curtidentata_ Dawson, Nova Scotia.
_(?) Amblyodon problematicum_ Dawson, Nova Scotia.
Family _Tuditanidæ_ Cope, 1875.
_Tuditanus punctulatus_ Cope, Linton, Ohio.
_Tuditanus brevirostris_ Cope, Linton, Ohio.
_Tuditanus minimus_ Moodie, Cannelton, Pa.
_Tuditanus longipes_ Cope, Linton, Ohio.
_Tuditanus walcotti_ Moodie, Linton, Ohio.
_Erpetosaurus acutirostris_ Moodie, Linton, Ohio.
_Erpetosaurus minutus_ Moodie, Cannelton, Pa.
_Erpetosaurus obtusus_ Cope, Linton, Ohio.
_Erpetosaurus radiatus_ Cope, Linton, Ohio.
_Erpetosaurus sculptilis_ Moodie, Cannelton, Pa.
_Erpetosaurus tabulatus_ Cope, Linton, Ohio.
_Erpetosaurus tuberculatus_ Moodie, Linton, Ohio.
_Odonterpeton triangularis_ Moodie, Linton, Ohio.
Family _Stegopidæ_ Moodie, 1909.
_Stegops divaricata_ Cope, Linton, Ohio.
Family _Urocordylidæ_ Lydekker, 1890.
_Diceratosaurus punctolineatus_ Cope, Linton, Ohio.
_Diceratosaurus lævis_ Moodie, Linton, Ohio.
_Diceratosaurus robustus_ Moodie, Linton, Ohio.
_Eoserpeton tenuicorne_ Cope, Linton, Ohio.
Family _Amphibamidæ_ Moodie.
_Amphibamus grandiceps_ Cope, Mazon Creek.
_Amphibamus thoracatus_ Moodie, Mazon Creek.
_Cephalerpeton ventriarmatum_ Moodie, Mazon Creek.
Family _Nyraniidæ_ Lydekker, 1889.
_Ichthyerpeton squamosum_ Moodie. Linton, Ohio.
_Cercariomorphus parvisquamis_ Cope, Linton, Ohio.
Family _Ptyoniidæ_ Cope, 1875.
_Ptyonius nummifer_ Cope, Linton, Ohio.
_Ptyonius marshii_ Cope, Linton, Ohio.
_Ptyonius vinchellianus_ Cope, Linton, Ohio.
_Ptyonius pectinatus_ Cope, Linton, Ohio.
_Ptyonius serrula_ Cope, Linton, Ohio.
_Œstocephalus remex_ Cope, Linton, Ohio.
_Œstocephalus rectidens_ Cope, Linton, Ohio.
_Thyrsidium fasciculare_ Cope, Linton, Ohio.
Family _Ichthycanthidæ_ Moodie.
_Ichthycanthus ohiensis_ Cope, Linton, Ohio.
_Ichthycanthus platypus_ Cope, Linton, Ohio.
Family _Molgophidæ_ Cope, 1875.
_Molgophis macrurus_ Cope, Linton, Ohio.
_Molgophis brevicostatus_ Cope, Linton, Ohio.
_Molgophis wheatleyi_ Cope, Linton, Ohio.
_Erpetobrachium mazonensis_ Moodie, Mazon Creek.
_Pleuroptyx clavatus_ Cope, Linton, Ohio.
_Phlegethontia linearis_ Cope, Linton, Ohio.
_Phlegethontia serpens_ Cope, Linton, Ohio.
Family _Sauropleuridæ_ Hay, 1902.
_Sauropleura digitata_ Cope, Linton, Ohio.
_Sauropleura newberryi_ Cope, Linton, Ohio.
_Sauropleura scutellata_ Newberry, Linton, Ohio.
_Sauropleura pauciradiata_ Cope, Linton, Ohio.
_Sauropleura longidentata_ Moodie, Linton, Ohio.
_Sauropleura foveata_ Cope, Linton, Ohio.
_Sauropleura (Anisodexis) enchodus_ Cope, Linton, Ohio.
_Sauropleura_ sp., Linton, Ohio.
_Ctenerpeton alveolatum_ Cope, Linton, Ohio.
_Saurerpeton latithorax_ Cope, Linton, Ohio.
_Leptophractus obsoletus_ Cope, Linton, Ohio.
_Leptophractus dentatus_ Moodie, Linton, Ohio.
_Leptophractus lineolatus_ Cope, Linton, Ohio.
Order Temnospondylia Zittel, 1887. Coal Measures and Permian.
Family _Cricotidæ_ Cope, 1884.
_Spondylerpeton spinatum_ Moodie, Mazon Creek, Ill.
Family _Eryopidæ_ Cope, 1882.
_Eryops_ sp. indet., Pitcairn, Pa.
Family _Macrerpetidæ_ Moodie, 1909.
_Macrerpeton huxleyi_ (Cope), Linton, Ohio.
_Macrerpeton deani_ Moodie, Linton, Ohio.
Family _Anthracosauridæ_ Cope, 1875.
_Eosaurus acadianus_ Marsh, Nova Scotia.
_Eobaphetes kansensis_ Moodie, Kansas.
_Baphetes planiceps_ Owen, Nova Scotia.
_Baphetes minor_ Dawson, Nova Scotia.
_Dendrerpeton acadianum_ Owen, Nova Scotia.
_Dendrerpeton oweni_ Dawson, Nova Scotia.
_(?)Platystegos loricatum_ Dawson, Nova Scotia.
Genera and species of uncertain position:
_Amblyodon problematicum_ Dawson, Nova Scotia.
_Proterpeton gurleyi_ Moodie, Illinois.
_Brachydectes newberryi_ Cope, Linton, Ohio.
Order Stereospondylia Zittel, 1887. Coal Measures (?) and Triassic.
Family _Mastodonsauridæ_ Huxley, 1863.
_Mastodonsaurus_ sp. indet., Kansas.
The above list of species is interesting in that it shows the diversity
of structure among the Coal Measures Amphibia. There are at present 88
species known, many of them incompletely, divided among 17 families and
5 orders. The majority of the species are from the Linton Coal Measures,
there being 50 species described or indicated from these beds. The Mazon
Creek shales have furnished 10 species; Nova Scotia 18 species; the
remainder of the species are from various localities.