THE TEMNOSPONDYLOUS AMPHIBIA OF THE COAL MEASURES OF NORTH AMERICA.
DEFINITION OF THE ORDER TEMNOSPONDYLIA, ZITTEL. 1887.
Zittel, Handbuch der Paleontologie, Abth. 1, Bd. 3, p. 384, 1887.
Terrestrial or semi-aquatic vertebrata; skull bones pitted and
grooved; lateral-line canals present in well-developed form; pineal
foramen sometimes absent; sclerotic plates present; vertebræ
rachitomous or embolomerous; notochord partly persistent; one or two
sacral vertebræ; tail present, long or short; limbs and girdles well
developed; limb bones well ossified and bones of arm and leg separate;
pectoral and pelvic girdles composed of the usual stegocephalian
elements; an osseous pubis present; a cleithrum present on the
scapula; carpus and tarsus ossified, carpals n and tarsals 12 in
one form; phalangeal formula, 2, 3, 3, 4, 2 for the hand and 2,
3, 3, 3, 2 for the foot; fore and hind limbs pentadactyl in a few
forms; venter covered with an armature of osseous scutes, sometimes
overlapping; skin of back bare or armored with heavy plates; ribs
heavy, double-headed, curved and moderately long, or short; body short
and heavy, as compared to skull about 2 to 1.
Range: Coal Measures to upper Permian.
Distribution: North America: Illinois, Kansas, Oklahoma, Texas, and
Pennsylvania; Europe: Germany, Bohemia; France; Asia: India.
=Family CRICOTIDÆ Cope, 1884.=
Cope, Am. Nat., XVIII, p. 38, 1884.
General form of the body elongate, with triangular skull and short,
stout limbs. Snout narrow, orbits large, elongated oval, situated near
the middle of the skull. External bones faintly sculptured, sensory
canals conspicuous, parietal foramen large. Teeth conical, of unequal
size. Presacral vertebræ composed of horseshoe-shaped pleurocentra
and hypocentra, the former alone supporting the neural arch. In the
caudals the pleurocentra and hypocentra form complete rings, and both
elements take part in the support of the neural arch, but the hæmal
arch is borne exclusively by the hypocentra. A close abdominal armor
of imbricate scales, arranged in a chevron pattern. Caudal vertebræ
numerous. Chevrons coössified with the intercentra.
=Genus SPONDYLERPETON Moodie.=
Moodie, Kans. Univ. Sci. Bull., vi. No. 2, p. 355, 1912.
Type: _Spondylerpeton spinatum_ Moodie.
The genus is based on a specimen consisting of 9 imperfect vertebræ,
from the caudal region of a relatively large amphibian. The present
genus exceeds _Diplospondylus_ from the Gaskohle of Bohemia (251)
by twice its size and is about two-thirds the size of _Cricotus
heteroclitus_ Cope (98) from the Permian of Kansas. The vertebræ are
twice as high as wide, differing thus from _Cricotus_, in which the
vertebræ are nearly circular. A character which is of great importance
is the large size of the intercentrum, which almost equals the
pleurocentrum in size. It is similar to the pleurocentrum in shape,
except for the attached neurocentrum and chevron on the latter. The
present genus differs from _Diplospondylus_ in the greater length of
the intercentrum and pleurocentrum, in the greater size, in the larger
proportions of the neurocentrum, and the greater proportionate size of
the intercentra.
=Spondylerpeton spinatum Moodie.=
Moodie, Kans. Univ. Sci. Bull., VI, No. 2, pp. 355-357, pl. 8, figs. 1
and 2; pl. 9, fig. 1, 1912.
Type: Specimen No. 793 (26) and obverse, Yale University Museum.
Horizon and locality: Mazon Creek, near Morris, Illinois.
The species is very imperfectly known. Sufficient is present, however, to
show its wide generic differences from other forms of the Cricotidæ. These
characters are of a phylogenetic nature and indicate the more primitive
nature of the present form, as we would expect from its geological
position. The sutures separating the four vertebral elements are clearly
apparent. The pleurocentral-neurocentral suture is apparent in 4 vertebræ.
[Illustration: Fig. 39. The vertebræ of _Spondylerpeton spinatum_ Moodie,
the only known temnospondyle from the the Mazon Creek shales. × 1. _hy_,
hypocentrum; _inc_, intercentrum; _pc_, pleurocentrum; _nc_, neurocentrum.]
There is but a single pleurocentrum preserved complete. This shows the
form of the attached neurocentrum and chevron, which corresponds to the
hypocentrum pleurale according to Fritsch. The pleurocentrum is flattened
laterally, with a rather large canal for the notochord. Its sides are
marked with 4 longitudinal grooves. Surfaces for the attachment of the
ribs are not present, and for this reason, as well as the presence of
chevrons, the vertebræ are supposed to be caudals. As such they represent
an animal of some 3 or 4 feet in length. It was the giant of the Mazon
Creek Amphibia. (Plate 4, figs. 1, 2.)
Attached to the upper side of pleurocentrum by a sutural union occurs
the neurocentrum. The neural arch is quite large and is oval in outline,
although somewhat constricted at the tip. The spine of the neurocentrum is
rather long and broad at the base, measuring 12 mm. across the anterior
zygapophysis. The neurocentrum is laterally flattened and ends in a rather
acute and somewhat rugose point. It was probably tipped with cartilage.
The anterior zygapophysis occurs well down on the neurocentrum, its lower
edge being 5 mm. from the suture separating the pleurocentrum and the
neurocentrum. The posterior zygapophysis occurs quite high up on the
neurocentrum and lies at a distance of 15 mm. from the pleuro-neurocentral
suture, thus indicating an extreme posterior inclination of the neural
spine. The posterior zygapophysis of the best preserved vertebra is
separated from its mate, the anterior zygapophysis, in the next succeeding
vertebra by a space of 5 mm.
The ventral surface of the pleurocentrum bears a structure, which is,
without doubt, a chevron, although the character of its opening can not
be determined. It is elongated and is united by a broad base to the
pleurocentrum. Its union is by a clearly defined suture, which is apparent
in 3 vertebræ. The condition represented by the specimen duplicates almost
exactly the condition figured by Cope for the caudal region of Cricotus
Cope.[D]
[Footnote D: COPE, E. D., Trans. Am. Phil. Soc., XVI, p. 246, 1890.]
The intercentrum of the present form is fully as large as the
pleurocentrum. The significance of this has already been mentioned. The
body of the centrum is pierced by a large notochordal canal.
Measurements of the Type of Spondylerpeton spinatum Moodie.
mm.
Length of specimen 60
Length of pleurocentrum 11.5
Height of pleurocentrum to base of neurocentrum 20
Length of neurocentrum 33
Width of neurocentrum at base 9
Width across anterior zygapophysis 12
Width across posterior zygapophysis 10
Length of intercentrum 10
Height of intercentrum 10.5
Height of chevron 3
Length of chevron 18
Width of notochordal opening in centrum 5
Height of same 4.5
Height of neural canal 12
Greatest width of neural canal 6
=Family ERYOPIDÆ Cope, 1882.=
Cope, Am. Nat., XVI, p. 334, 1882.
Large, terrestrial or amphibious vertebrata; skull bones deeply marked
with pits and grooves which take the form of lateral-line canals;
infra- and supraorbital canals, antorbital commissure, jugal canal,
and occipital cross-commissure of the lateral-line system present
in _Eryops megacephalus_ Cope; carpus and tarsus osseous; pubis an
osseous plate, surrounded in life by a large amount of cartilage; fore
and hind limbs pentadactyl; orbits, in the typical genus, located far
back on the skull and near the median line; cleithrum present on the
scapula; vertebræ rachitomous, the intercentrum supporting the arch in
the dorsal region; parasphenoid well-developed or reduced; teeth on
pterygoids, palatines, prevomers, and parasphenoid.
Range: Upper Pennsylvanian to Permian.
Distribution: America, Europe, Asia.
=Genus ERYOPS Cope, 1877.=
Type: _Eryops megacephalus_ Cope.
Skull long, comparatively narrow; proportion of length to breadth
about 9 to 7. Roof bones coarsely sculptured posteriorly, finely
sculptured anteriorly. Nasals and premaxillæ very large; frontals
excluded from the orbits by junction of pre- and post-frontals.
Pterygoids not meeting in the median line; parasphenoid dagger-shaped,
tapering gradually to a point just in front of the palatine foramen;
prevomers large. Orbits subcircular, situated in the posterior half
of the skull; nares subovate, remote, at a considerable distance from
the tip of the skull. Many minute denticles, on pterygoids, palatines,
prevomers, and parasphenoid. Teeth circular in cross-section, strongly
ribbed near the base, dentine strongly infolded. Three large teeth
on each palatine. Mandible without postcotyloid process. Vertebræ
rachitomous. Ribs double-headed. Pubis osseous. Three species
(Permian), _E. megacephalus_, _E. latus_, and _E. willistoni_, are
assigned to the genus.
Eryops is represented in the Carboniferous deposits of North America by
incomplete vertebral remains described by Case (94) from near Pittsburgh,
Pennsylvania.
[Illustration: MOODIE PLATE 25
1. Photograph of type specimen of _Erpetosaurus_ (_Tuditanus_)
_radiatus_ Cope, from the Coal Measures of Linton, Ohio. × 1.3.
Original in American Museum of Natural History.
2. Photograph of type specimen of _Erpetosaurus tabulatus_ Cope,
from the Coal Measures of Linton, Ohio. × 2. Original in the
Zoological Collections of Columbia University.
3. Photograph of the impression of _Stegops divaricata_ Cope, from
the Coal Measures of Linton, Ohio. × 2. The specimen figured is
in the American Museum of Natural History. Its obverse is in the
collections at Walker Museum, University of Chicago.
4. Type and only known specimen of _Micrerpeton caudatum_ Moodie,
a branchiosaur from the Coal Measures shales of Mazon Creek,
Illinois. × 2. Original in collections at Walker Museum,
University of Chicago.
]
=Eryops sp. indet. Case, 1908.=
Case, Annals Carnegie Mus., IV, p. 234, pl. 59, 1908.
A dorsal vertebra is very probably from this genus. The specimen consists
of a nearly perfect vertebra, lacking only the anterior zygapophysis and
the upper portion of the neural spine (plate 18, fig. 2). It shows no
character that would warrant its separation from the genus, and indicates
a medium-sized individual. The zygapophyses have clean-cut articular
faces. The pleurocentra are thickened above, with just well-defined
articular faces, which were applied to faces on the neural arch posterior
to the origin of the transverse process. The intercentrum is of the
familiar halfmoon-shape, thick and heavy below, and thinner toward the
extremities; the anterior edge is marked near the top by the indentation
found on the intercentra of _Eryops_.
Height of the vertebra from the middle of the lower face of the
intercentrum to the middle of the neural canal, 0.035 m.; width of
intercentrum 0.026 m.
The second recognizable specimen is a neural spine from the caudal series.
This is without question a portion of the skeleton of an Eryops. Similar
spines were described by Cope as _Eryops (Epicordylus) erythrolithicus_,
but later discoveries seem to show that similar characters occur in other
species of the genus as well. The apex of the spine is bifurcate; the
space between extremities is concave and perfectly smooth; below the sides
of the spine are rather rugose and marked with ridges. The lower portion
of the spine is elongated anteroposteriorly and the edges are marked with
sharp, double ridges.
Three ribs also belong, in all probability, to the genus _Eryops_. The
head of each rib is broad and the articular edge is divided between two
faces which meet at an angle somewhat greater than a right angle; the
two faces are continuous. The shaft is somewhat flattened and in the
undistorted specimens is gently curved. The length of the largest rib is
about 0.07 m.
Other than these specimens there are several small intercentra (94) and
the neural spine of a caudal vertebra from some undetermined amphibian.
=Family MACRERPETIDÆ Moodie, 1909.=
Moodie, Bull. Am. Mus. Nat. Hist., XXVI, art. XXV, p. 354, pl. lix,
fig. 1, 1909.
It has seemed necessary to propose a new family for the reception of the
single species _Macrerpeton_ (_Tuditanus_) _huxleyi_ Cope. The characters
exhibited by this species are so different from those offered by other
members of the Carboniferous Microsauria that it is clearly distinct. In
its cranial characters and the position of the orbits it approaches most
nearly to _Eryops megacephalus_ Cope from the Permian of Texas. In some of
its characters the present form shows a similarity to _Dasyceps bucklandi_
Lloyd (324), from the Permian of Kenilworth, England; more especially is
this similarity found in the form of the skull, the size and shape of the
teeth, and the posterior position of the orbits, and their wide removal
from the border of the skull. Only a fragment of the skull has hitherto
been known, but repeated study of this fragment (123) has disclosed
the wide diversity (462) of its characters. An almost complete skull,
described below, substantiates the characters based on the fragment.
Another species is here added to the genus, based on a portion of a
mandible and a portion of the skull.
The family, Macrerpetidæ, may be defined (465) as follows:
Skull larger than in any other known microsaurian, unless Baphetes
proves to be microsaurian; cranial elements sculptured with pits and
coarse grooves; lacrimal element present, teeth large, curved inwards
and fluted; mandible heavy; orbits located far back on the skull and
near the median line so that the interorbital space is about half the
space from the outer edge of the orbit to the border of the skull,
thus approaching the condition known in Eryops; the ribs (?) are
strong, heavy, and curved, with an incipient tubercle.
=Genus MACRERPETON Moodie, 1909.=
Moodie, Jour. Geol., XVII, No. 1, pp. 72-74, fig. 17, 1909.
Type: _Macrerpeton huxleyi_ Cope.
The genus _Macrerpeton_ was proposed for the reception of the amphibian
species described by Cope as _Tuditanus huxleyi_ (123). This form he
placed provisionally in genus _Tuditanus_, since it seemed to present the
same type of sculpturing of the cranial elements similar to that found
in _T. radiatus_ Cope. But this species has been removed from Tuditanus
and placed in a new genus, _Erpetosaurus_ (462). A close study of the
type specimen of _Tuditanus huxleyi_ Cope shows (465) great variation and
distinction from any of the species described from Linton, Ohio, or indeed
from any Carboniferous form thus far known.
The specimen represents the left side of the face, and the characters
exhibited by the fragment are supported by more complete material (No.
2933, Am. Mus. Nat. Hist.). The skull shows a close approach to the higher
labyrinthodonts in its shape. The orbits are far removed from the border
of the skull. The arrangement of the bones of the skull resembles that
of _Capitosaurus_ from the Keuper of Europe. The jaw is for the most
part slender, with a pronounced downward inflection at the coronoidal
part. The teeth are heavy and strong and are curved backwards. They
have the strong longitudinal fluting which is characteristic of the
labyrinthodonts. Another character which is distinctive is the pattern of
cranial sculpture. This consists of inosculating pits and grooves of a
coarse character and compares favorably with the sculpturing of Triassic
labyrinthodonts. If _Macrerpeton_ really represents a labyrinthodont form
of Amphibia it is the oldest of the known Labyrinthodontidæ, since it
seems probable that the _Eosaurus_ vertebræ came from a higher horizon.
=Macrerpeton huxleyi Cope, 1874.=
Cope, Trans. Am. Phil. Soc., XV, p. 274, 1874.
Cope, Geol. Surv. Ohio, II, pt. II, p. 397, pl. xxxiv, fig. 2, 1875.
Lesley, Dictionary of Fossils, p. 1237, 1890.
Moodie, Jour. Geol., XVII, No. 1, p. 72, fig. 17, 1909.
Moodie, Bull. Am. Mus. Nat. Hist., XXVI, art. XXV, p. 354, pl. lix,
fig. 1, 1909.
Type: Specimen No. 119, American Museum of Natural History. Collection of
Dr. J. S. Newberry. (Plate 26, fig. 2.)
Horizon and locality: Linton, Ohio, Coal Measures.
[Illustration: MOODIE PLATE 26
1. Photograph of type specimen of _Erpetosaurus tuberculatus_
Moodie, from the Ohio Coal Measures. × 1. Original in American
Museum of Natural History.
2. Photograph of type of _Macrerpeton huxleyi_ Cope, from the Ohio
Coal Measures. × 1. Original in American Museum of Natural
History.
]
The first part of the following account of the species, _Macrerpeton
huxleyi_ Cope, is a quotation of Cope's description (123) of the type
specimen, and the second part deals with the description of the new
material. Cope says the species is
"Represented by a considerable portion of the face and muzzle of a
single individual. A portion of the left mandible, supporting three
teeth, remains in place, and almost the entire boundary of the right
orbit is preserved.
"The fragment indicates a much larger species than any other referred
to the genus, and, next to the _Leptophractus obsoletus_, the largest
of the Batrachians of the Ohio Coal Measures. Without more complete
remains, it is not easy to determine its generic relations finally.
"The form of the head is probably elongate, and the muzzle neither
very obtuse nor elongate. The orbit is rather small, and near the
middle of the length of the specimen, which is, however, incomplete at
both ends. The sculpture of the surface of the head posterior to the
orbits, as well as round their borders and for some distance in front
of them, consists of a rather coarse pitting. On the middle line,
between the orbits and on the muzzle, the intervals become narrower,
and are confluent into transverse ridges or a delicate reticulation.
The surface of the mandible displays a coarse reticulation.
"The teeth are stoutly conic, and with delicately striate grooved
cementum. They are slightly recurved.
"This species differs from the _T. radiatus_ and _T. obtusus_ in the
absence of the area into which the sculpture is thrown.
"Longitudinal diameter of orbit, 19 mm.; length of alveolar border
supporting three teeth, 13 mm.; diameter of base of tooth, 3 mm.;
eight pits in 10 mm.
"Dedicated to Professor T. H. Huxley, _facile princeps_ among English
systematists, and an important contributor to the knowledge of the
extinct Batrachia."
The following discussion of the cranial elements, based on the writer's
studies (462, 465) of the type, may be appended to Professor Cope's
original description. The sutures bounding a few of the elements have
been made out in part. The prefrontal element seems well assured. It lies
well in front of the orbit, much as in the skull of _Capitosaurus_ from the
Keuper of Europe. The lacrimal is, apparently, a very large bone, though
its entire extent is not assured.
The maxilla is a long, narrow element on the border of the skull. The
suture separating this from the lacrimal and jugal is quite clear. The
teeth which the maxilla undoubtedly bore are hidden by the remains of the
mandible, which lies partly on the edge of the skull. The jugal is a very
large element and its boundaries seem well assured. Its size and relations
recall the condition in Capitosaurus. It forms a part of the external
boundary of the orbit. The lateral suture of the postorbital is evident
and is, as shown in the figure, somewhat curved. The remaining elements
preserved on the fragmentary skull can not be accurately determined,
though their probable position is indicated in plate 30, fig. 2, the
lettering being based on the arrangement of these elements in Capitosaurus.
The lower jaw is poorly preserved, but what remains shows evidence of
being sculptured somewhat after the manner of the cranial elements. It
bore strong recurved teeth which are longitudinally striate.
Measurements of the Type Specimen of Macrerpeton huxleyi Cope.
mm.
Length of portion preserved 120
Maximum width of specimen 58
Length of orbit 20
Width of orbit 14
Length of jaw, as preserved 75
Width of jaw at widest part 11
Length of longest tooth 8
Width of tooth at base 4
Description of Additional Material of Macrerpeton huxleyi.
The additional material of this species which has come to hand consists of
an almost complete skull (American Museum No. 2933, two portions); another
fragmentary skull (American Museum No. 8572 G and 8532 G); a portion of
an interclavicle (American Museum No. 8006); two incomplete vertebræ
(American Museum No. 8007); and another fragmentary element possibly
representing a scapula of this species (American Museum No. 8008).
The skull has essentially the shape outlined (462) from a study of the
fragmentary type specimen. The muzzle was drawn slightly too broad, but
otherwise the restoration is fairly accurate. The specimen is distorted
and imperfect, but enough is preserved to give a good idea of the shape
and something of the structure of the skull. A portion of the obverse is
preserved. The back part of the skull is broken, so that the occiput can
not be studied.
The length of the skull is one and two-fifths the greatest breadth (across
the orbits). The cranial elements are deeply marked with pits and short,
shallow grooves. On the left mandible these pits are in a very distinct
row, the _operculo-mandibular lateral-line_.
=Macrerpeton deani new species.=
Type: Specimen No. 2934, American Museum of Natural History.
Horizon and locality: Linton, Ohio, Coal Measures. (Plate 21, figs. 1, 2.)
The material for this species consists of the posterior half of the left
mandible and a portion of the right antero-lateral surface of the skull,
both incomplete. The reasons for regarding the species as distinct are the
large size of the specimens and the manner of the sculpture, as well as
the shape of the posterior end of the mandible.
[Illustration: Fig. 40. Mandible of Macrerpeton deani new species, from
Linton, Ohio. × 0.75.]
The present species is the largest amphibian of the Linton, Ohio, Coal
Measures, exceeding in skull length that of _Macrerpeton huxleyi_ by
twice. The largest skull of _Macrerpeton huxleyi_ which has so far
come under my notice is 120 mm. in median length. There are 3 skulls
of this species known, all of approximately the same size. The skull
of _Macrerpeton deani_ must have reached or exceeded a foot in median
length. The only species with which it can at all be compared are
_Eobaphetes kansensis_ Moodie and _Baphetes planiceps_ Owen, but it
is clearly distinct from all other genera of Linton Amphibia. It is
possible that when better known _Macrerpeton_, _Eobaphetes_, _Baphetes_,
_Erpetosaurus_, and possibly _Dendrerpeton_ will form a natural group of
early labyrinthodont-like Amphibia.
The mandible is similar in structure to that of the labyrinthodonts,
with the elements marked by radiate flutings. I can detect no evidences
of a lateral-line canal, such as is clearly marked in _Macrerpeton
huxleyi_ Cope by a series of rounded pits, occupying the usual position
of the operculo-mandibular lateral-line canal The teeth, of which 6 are
preserved, are minutely striate, with smooth apices. They are dissimilar
in size, showing a variation of 2 or 3 mm. in length.
The sculpture is a coarse fluting, with no indications of the sharply
marked pits of _Macrerpeton huxleyi_ Cope.
The fragment of a skull preserved shows characters of the sculpture which
are identical with those of the mandible. The bones are so crushed that it
is impossible to tell the limits of the elements. I believe a portion of
one orbit is represented on one corner of the block. The cranium appears
to have been broad, and the fragment preserved, which is only about
one-sixth of the skull, is larger than the entire cranium and mandibles of
_Macrerpeton huxleyi_.
The specific distinctness of the form can not be doubted, although it is a
matter of regret that it is founded on so small a portion of the osteology
of the animal.
The species is proposed in honor of Dr. Bashford Dean, to whom I am
greatly indebted for many kindnesses during the past 5 years in connection
with my studies on Carboniferous Amphibia, particularly in the loan of the
entire Newberry collection of Linton, Ohio, Amphibia.
Measurements of the Type of Macrerpeton deani Moodie.
mm.
Length of portion preserved 115
Greatest width 50
Length of tooth 9
Width at base 4
Length of angular 95
Diameter of angular 25
Measurements of specimen No. 8535 G, American Museum
of Natural History, associated with the above in
the type description:
Length of preserved portion 140
Diameter of orbit 22
=Family ANTHRACOSAURIDÆ Cope, 1875.=
Cope, Bull. U. S. Nat. Mus., I, p. 10, 1875.
Lydekker, R., 1890, Cat. Fossil Reptilia and Amphibia, p. 157.
Skull usually triangular and more or less angulated, with the cranial
sculpture well marked, the occipital condyles ossified, and the
palatine foramina very small and placed far back; dentine of the
teeth more or less complexly plicated. A ventral armor of elongated
dermal scutes, and probably a sclerotic ring. Bodies of vertebræ fully
ossified in the adult; intercentra present or absent. According to
Atthey's figure (11) of the skull of the type genus, the palatine
bears teeth which are situated immediately on the inner side of the
maxilla, as in Mastodonsaurus (242). In the typical forms there is no
postarticular process to the mandible.
The North American species of this family are: _Eosaurus acadianus_
Marsh, _Eobaphetes kansensis_ Moodie, _Dendrerpeton acadianum_ Owen,
_Dendrerpeton oweni_ Dawson, _Platystegos loricatum_ Dawson, _Baphetes
planiceps_ Owen, _Baphetes minor_ Dawson.
There is but little assurance that any of these species belong in this
family. They are put there provisionally, pending future discoveries.
Huxley suggests the relationship of _Eosaurus_ and _Anthracosaurus_
(Quart. Jour. Geol. Soc., XIX, 1863, p. 65; Scientific Memoirs, II, p.
566).
=Genus BAPHETES Owen, 1854.=
Owen, Quart. Jour. Geol. Soc. London, X, p. 207, pl. ix, 1854.
Dawson, Air-breathers of the Coal Period, pp. 10-16, pl. ii, 1863.
Type: _Baphetes planiceps_ Owen.
Known only from an incomplete skull, which is large, broader than long;
squamosals prolonged into obtuse horns. Teeth rather large, heterodont,
arranged in a single row. Orbits placed well forward, frontals small,
surface bones sculptured.
=Baphetes planiceps Owen.=
Owen, Quart. Jour. Geol. Soc. London, X, p. 207, pl. ix, 1854.
Dawson, Air-breathers of the Coal Period, pp. 10-16, pl. ii, 1863.
Type: Specimen in the British Museum of Natural History.
Horizon and locality: Near Pictou, Nova Scotia (Coal Measures).
The parts preserved include the premaxillaries, nasals, and portions of
the frontal, prefrontal, and maxillary bones. The fossil is embedded
in a mass of Pictou Coal from Nova Scotia and consists of the anterior
extremity of the cranium (plate 22, fig. 6) and with the exterior surface
of the bone embedded in the matrix, and its substance, for the most
part, reduced to a thin layer by abrasion of the exposed inner layer. It
displays accurately the contour of the fore part of the upper jaw, which
was broad, obtuse, and rounded.
The premaxillaries, which show some obscure traces of a symphysial suture
at the median line, anterior to the nasal or naso-palatine vacuities,
extend outwards, on each side, for an extent of 2.5 lines and there
join the maxillaries. Traces of round alveoli for teeth, some of which
are 2 lines in diameter, are visible on the alveolar border of the
premaxillaries. The alveolar border is continued by the maxillary bone for
an extent of 4.5 inches beyond the premaxillary border, and this border
shows still more distinct traces of alveoli, of a circular form, about a
line in diameter and rather close set in a single series. The fore part
of the orbit is very unequivocally displayed, the smooth inner or under
surface of the bone forming that part being entire; and this shows the
fore part of the orbit to be formed, partly by the maxillary, partly
by the lacrimal or prefrontal bone in close sutural union therewith,
a structure which does not exist in any recent or fossil fish with a
dentigerous superior maxillary bone. Where the substance of the bone has
been detached so far as to expose the external layer in contact with
the coal, as, _e.g._, on the frontal and part of the prefrontal bones,
the external surface of those bones is shown to have been impressed by
subhemispherical or elliptical pits, from 1 line to 1.5 lines in diameter,
and with intervals of half of that extent. This coarsely pitted character
agrees with that presented by the other surface of the similarly broad and
flat cranium of the labyrinthodonts.
From the characters above specified, therefore, I conclude that this
fossil is the fore part of the skull of an extinct family of the
labyrinthodonts. It agrees with them in the number, size, and disposition
of teeth; in the proportions and mode of connection of the premaxillaries,
maxillaries, nasals, prefrontals, and frontals, and in the resultant
peculiarly broad and depressed character of the skull. The traces of
the nostrils are less definite and satisfactory than the remains of the
orbits, but the latter appear to be decisive against the piscine nature
of the fossil. The fossil also presents the same well-marked external
sculpturing as in the labyrinthodonts; and among the genera that have
been established in that family, the form of the end of the muzzle, or
upper jaw, in the Pictou coal specimen best accords with that in the
_Capitosaurus_ and _Metopias_ of von Meyer and Burmeister (80).
Measurements of the Skull of Baphetes planiceps Owen.
(Type in the British Museum of Natural History, London.)
mm.
Approximate median length of skull 136
Width of skull across base of horns 150
Estimated width across tips of horns 186
Width of horn at base 31
Estimated length of horn from base 80
Width of skull across orbits 97
Diameter of orbit 21
Diameter of large tooth alveolus 7
Diameter of small tooth alveolus 2
Pictou Coal, near Pictou, Nova Scotia, Canada, collected by Dr. J. William
Dawson, 1850, and presented by him to the Geological Society of London.
=Baphetes minor Dawson.=
Dawson, Canadian Nat. and Jour. Sci., n. s., 1870, V, pp. 98, 99.
Type: Specimen in the Peter Redpath Museum, McGill University.
Horizon and locality: Coal formation of Nova Scotia.
The species was based on a lower jaw of an amphibian, of which a cast had
occurred in the coarse sandstone of the coal formation between Ragged Reef
and the Joggins Coal Mine. It measured 6 inches in length; its surface
was marked on the lower and posterior part with a network of ridges
inclosing rounded depressions. The anterior part of the jaw contained
about 16 teeth, some of which remained in the matrix. These were stout,
conical and blunt, with large pulp cavities, and about 32 longitudinal
striæ, corresponding to the folds of the dentine. Dawson states that this
jaw resembles most closely those of _Baphetes_ and _Dendrerpeton_, but more
especially the former. He regarded it as distinct from _Baphetes planiceps_,
and proposed for it the name _Baphetes minor_.
=Eosaurus acadianus Marsh.=
Marsh, Am. Jour. Sci. (2), XXXIV, pp. 1-16, pls. i, ii, 1862.
Agassiz, Am. Jour. Sci., XXXIII, p. 138, 1862.
Marsh, Quart. Jour. Geol. Soc., XIX, pp. 52-56.
Hay, Cat. Fossil Vertebrates (Bull. U. S. Geol. Surv. No. 179, p. 421,
1902).
Type: Specimen No. 1648, Yale University Museum.
Horizon and locality: South Joggins, Nova Scotia (Coal Measures).
The genus and species are founded on two vertebral bodies of the
stereospondylous type from the Coal Measures of the South Joggins, Nova
Scotia. Marsh's description (404) is as follows:
"The general form of the vertebræ is cylindrical, but their sides
are compressed obliquely, which gives to the contour of the centra a
subhexagonal appearance. They are much flattened in the direction of
the antero-posterior diameter, which has to the transverse diameter
the proportion of 1 to 3. Both the articular terminal facets are
deeply and equally concave; but from the center to the margin the
surfaces are convex, and this convexity is greatest near the center.
* * * The cavities for the reception of the intervertebral matter
begin immediately from the margin, and are considerably deeper
than the corresponding parts of the _Ichthyosaurus_, indicating a
greater degree of flexibility in the vertebral column. The margins
of the vertebra; are somewhat raised, as if they had yielded to a
forcible compression applied longitudinally; and hence the lateral
surfaces of the centers are concave in an antero-posterior direction.
This concavity is greater in the upper half of the vertebra and
was undoubtedly more marked originally than at present, since the
appearance of the margins indicates considerable abrasion. The
non-articular surfaces of the centra are smooth and regular; and the
external fibres of the osseous tissue are singularly reticulated.
[Illustration: Fig. 41. Nova Scotian Amphibia.
A. Oblique lateral view of vertebra: of _Eosaurus acadianus_ Marsh,
_a_, pits for articulation of neuropophyses; _b_, rudimentary
transverse process on right lateral surface of centrum.
B. Oblique view of vertebræ, _a_, pits for articulation of
neuropophyses; _b_, rudimentary process on lateral surface.
C. Posterior view of nearly perfect centrum.
D. Transverse section of same vertebra, showing deep concavities of
articular terminal facets.
E and F. Microscopic sections near surface, showing lacunæ arranged
around an Haversian canal. Magnified 200 diameters.
(All figures after Marsh. × 0.75.)
]
"The neuropophyses are not anchylosed to the centrum, as in the
mammalia, nor connected to it by sutures, as in the crocodiles;
but their union with the vertebra is indicated by two pits, which
served for their articulating surfaces. These depressions are
situated on the superior surface of the centrum intermediate between
the anterior and posterior margins of the extremities. They are
circular in form and sink directly into the body of the vertebra;
instead of being elongated longitudinally and raised by ridges, as
in _Ichthyosaurus_. The pits are about a line in depth, and in the
more perfect of the fossils are not in their original position. The
floor of the spinal canal is narrow, being but 5 lines in breadth. A
rudimentary transverse process, or exogenous tubercle, is sent off
from each lateral surface of the centrum, at points equidistant from
the extremities of the vertical diameter. Their position is near the
margin of the anterior articular surface, and the edges of these
parapophyses make the transverse diameter of this extremity somewhat
greater than that of the corresponding posterior facet."
Measurements of the More Perfect Vertebra of Eosaurus acadianus (after
Marsh).
mm.
Transverse diameter of centrum on anterior surface 59
Same on posterior surface 57
Same including the parapophyses 63
Vertical diameter of anterior surface 54
Anteroposterior diameter on superior surface 21
Same on inferior surface 19
Same between centers of articular facets 2.5
Length of pits for articulation of neural arch 7
Breadth of same 7
Depth of same 2
Distance between centers of same 11
Same at centers of parapophyses 36
Collected by O. C. Marsh at the South Joggins, Nova Scotia.
Marsh regarded (404) the vertebræ as representing a new type of
ichthyosaurian (2), but there can be no doubt that the vertebræ belong
to some form of the Amphibia, since the description applies equally well
to them. In this connection mention must be made of a large rib from the
Linton beds preserved in the U. S. National Museum. Only the proximal
third of the rib is preserved, but it represents some large form of the
Stegocephala. The rib is strongly curved backward, is heavy, and has an
incipient tubercle. A cross-section shows that a longitudinal groove
occupies the median line on the exposed surface of the rib. This may,
however, be due to compression and thus indicate that the rib was hollow.
The rib as preserved measures: length, 102 mm.; maximum width, 22 mm.;
minimum width, 14 mm. (Nos. 4490, 4489, U. S. National Museum.)
=Genus EOBAPHETES new name.=
Type: _Eobaphetes kansensis_ Moodie.
The new name is proposed to replace the generic term _Erpetosaurus_ used
for the species _E. kansensis_ described by the writer (Proc. U. S. Nat.
Mus., 39, p. 491, 1911), and which later was found to be preoccupied by
Newton (Phil. Trans. Roy. Soc. London, 185, p. 573, 1894 B).
The genus is very readily distinguished by two prominent characters the
short, uniform dentition and the presence of two elongate, oval, internal
mandibular foramina on the inner side of the jaw. The genus may be further
distinguished by the great depth of the posterior portion of the jaw and
the slender anterior part, as well as by the ornamentation, which is
typically the rough tuberculated labyrinthodont sculpture on the anterior
end of the mandible. This changes gradually to longitudinal grooves and
ridges of a rather small size on the posterior portion, a very unusual
arrangement for a labyrinthodont.
These characters are sustained by those of the skull fragment, in
which the dentition is uniform and the sculpture very similar to that
of the mandible. The ribs are long, curved, and solid, as in other
labyrinthodonts.
The internal surface of the mandible shows much similarity to that of the
crocodiles and alligators of the present day. The resemblance is not due
to homology of structures, but must be regarded as a parallel development
of similar characters.
=Eobaphetes kansensis Moodie.=
Moodie, Proc. U. S. Nat. Mus., 39, pp. 491-494, figs. 1 to 3, 1911
(_Erpetosuchus_).
Type: Specimen No. 6699, U. S. National Museum.
Horizon and locality: Coal Measures of Washington County, Kansas.
The species is represented in the collections of the U. S. National Museum
by a fragment of the skull, with portions of two ribs (Cat. No. 6699,
Vert. Pal. U. S. Nat. Mus.) and the larger part of the left ramus of the
mandible (Cat. No. 6680, Vert. Pal. U. S. Nat. Mus.). The mandible was
preserved in a large block of coal which contained the impression of the
back portion of the mandible from which the bone had been weathered. It
was possible to remove the bone and make a plaster cast of the impression.
This shows in a very satisfactory manner all of the characters of the
external surface.
_Skull._--Only a portion of the left maxilla, with 14 teeth, and a part of
the nasal are preserved. The skull seems to have been laterally crushed
and the right side of the skull has been crushed flat under the left. It
has not seemed feasible to remove the skull from the matrix.
The teeth are uniform, rather short, bluntly conical, curved backward, and
coarsely striate. They are somewhat crowded, the bases being separated
from each other by only a fraction of a millimeter.
The maxilla and portion of the nasal are coarsely sculptured with elongate
pits and ridges. A portion of the infraorbital lateral-line canal is
preserved. It is simply a rounded groove with three short branches. It
lies near the middle of the maxilla.
_Mandible._--It has been possible to study both sides of the mandible.
The left ramus was preserved in the coal, with its inner face exposed.
This face is broken by two large oval openings, the internal mandibular
foramina. This is the term used by Reynolds for the openings on the inner
surface of the alligator jaw. So far as I can ascertain, no other known
labyrinthodont mandible displays this character in such a marked degree.
Dr. Branson has figured in _Anaschisma browni_ Branson from the Triassic
(49) of Wyoming the inner surface of the left ramus, on which there are
likewise two openings but differently situated. A similarity between the
two mandibles is observed in that the suture separating the prearticular
and angular touches the posterior edge of the posterior foramen.
Several of the sutures are well preserved and they have been indicated
in the drawing (fig. 42). The pillar separating the two foramina is cut
by the suture separating the angular and prearticular very much as in
_Anaschisma_, with the difference that in the latter form the angular
and prearticular are not approximated. I believe I detect the suture as
represented separating the anterior end of the angular from the dentary
and splenial. I am assured of the portion near the anterior foramen and
also of the part near the tip of the ramus. This shows the angular to be
a very elongate element, running very nearly the entire length of the
mandible, much as in _Anaschisma_ and other labyrinthodont genera. The
splenial is a small, slender element located farther forward, where it
has been shoved by the large-sized internal mandibular foramina. The
prearticular is a rather long, broad element, of which only a portion is
preserved. I am not sure as to the location of the suture for the dentary,
unless it is represented by the line bounding the roughened area near the
teeth. If this is true, the dentary is a large element, since it extends
well down upon the outer side of the jaw. The dentary possesses evidences
of 26 teeth, a few of which are completely preserved. Most of them are,
however, represented either by bases or by impressions in the coal. The
teeth are very similar to those of the maxilla, though slightly larger.
The characters given for the maxillary teeth will suffice for those of the
dentary.
[Illustration: Fig. 42.
A. Outer view of mandible of _Eobaphetes kansensis_ Moodie, from
the Coal Measures of Washington County, Kansas. Original in U.
S. National Museum. × 0.33. Cat. No. 6680. _a_, angular; _r_,
articular; _d_, dentary.
B. Portion of skull of _Eobaphetes kansensis_ Moodie, from the Coal
Measures of Washington County, Kansas. Original in U. S. National
Museum. Cat. No. 6699. × 0.33. Lateral-line canal represented by
heavy broken line, _n_, nasal; _m_, maxilla.
C. Inner surface of mandible of _Eobaphetes kansensis_ Moodie, from
the Coal Measures of Washington County, Kansas. × 0.33. _a_,
angular; _p_, prearticular; _r_, articular; _s_, splenial.
]
The markings of the inner surface are as indicated in the drawing. The
back portion of the angular shows a few radiating lines. The dentary is
roughened in two portions: one near the teeth, the other at the tip, where
there is a cartilaginous roughening for union with its mate. The remainder
of the inner surface is relatively smooth.
The outer surface shows at the anterior end the typical labyrinthodont
sculpturing, which becomes slight grooves and ridges posteriorly. I detect
evidences of the operculo-mandibular lateral-line canal throughout the
entire length of the mandible. Its location is indicated by the heavy
broken line. The suture between the dentary and angular is quite clear.
The suture separating the dentary and splenial joins the angular suture
about midway of the length of the jaw.
Measurements of Skull Fragment of Eobaphetes kansensis Moodie.
(Cat. No. 6699, U. S. Nat. Mus.)
mm.
Total length of portion preserved 109
Maximum width of maxilla 45
Thickness of maxilla 7
Length of tooth 10
Width of tooth at base 4
Measurements of Left Ramus of Mandible of Eobaphetes kansensis Moodie.
(Cat. No. 6680, U. S. Nat. Mas.)
mm.
Total length of jaw, as preserved 305
Greatest width 79
Least width 24
Length of angular 132
Width of angular 45
Length of largest tooth 10
Width of largest tooth at base 6
Length of most posterior tooth 6
Width of most posterior tooth at base 4
Length of anterior internal mandibular foramen 56
Greatest width 15
Least width 7
Length of posterior internal mandibular foramen 77
Greatest width 28
Least width 14
Length of bridge 16
Width of bridge 8
_Ribs._--There are portions of two dorsal ribs preserved on the block of
coal with the skull. These show characters very similar to those exhibited
by the rib ascribed to _Macrerpeton huxleyi_ Cope, and also those of
_Metoposaurus diagnosticus_ von Meyer (242) and _Anaschisma_. The ribs
are solid, heavy, curved, and have a longitudinal groove on the middle of
each side. The heads of the ribs in the present specimen are obscured and
nothing can be said of them except that they appear to be large.
Measurements of Ribs of Eobaphetes kansensis Moodie.
mm.
Length of preserved portion 130
Width at distal end 18
Thickness of rib 5
=Genus DENDRERPETON Owen, 1853.=
Owen, Quart. Jour. Geol. Soc. London, IX, p. 66, 1853.
Type: _Dendrerpeton acadianum_ Owen.
The genus is characterized by Dawson as follows (Phil. Trans., 1882, p.
635):
"Lizard-like, with anterior and posterior extremities nearly equal;
the skull somewhat elongate with small orbits, and the nostrils placed
at the front. The cranial bones sculptured. The teeth plicated at the
base, more especially on their inner sides. A series of large teeth on
the palate. The body was covered above with imbricated horny scales
and had lappets or pendants at the sides. The abdomen was protected by
thin bony scales semi-elliptical or oat-shaped in form, and arranged
in a chevron pattern. There was probably also a thoracic plate. Two
species: _D. acadianum_ and _D. oweni_.
"Type: _D. acadianum_ Owen."
=Dendrerpeton acadianum Owen.=
Owen, Quart. Jour. Geol. Soc. London, IX, p. 66, 1853.
Dawson, Air-breathers of the Coal Period, p. 17, 1863.
Dawson, Acadian Geology, 3d ed., p. 362.
Dawson, Phil. Trans. Roy. Soc. London, pt. II, p. 642, pl. 40, figs.
46 to 51; pl. 44, figs. 129 to 137. 1882.
Type: Specimens Nos. 434-438, British Museum of Natural History. Horizon
and locality: Coal formation at South Joggins, Nova Scotia. (Plate 6.)
This species has been fully described and figured by Dawson (Air-breathers
of the Coal Period, pp. 17-30, pl. III, figs. 1 to 30, 1863), who gives
a detailed account of the discovery of the material of this species by
himself and Sir Charles Lyell. He says, in part:
"In form, _Dendrerpeton acadianum_ was probably lizard-like; with a
broad flat head, short, stout limbs and an elongated tail; and having
its skin, and more particularly that of the belly, protected by small
bony plates closely overlapping each other. It may have attained
the length of 2 feet. The form of the head is not unlike that of
_Baphetes_, but longer in proportion; and much resembles that of the
labyrinthodont reptiles of the Trias. The bones of the skull are
sculptured as in _Baphetes_, but in a smaller pattern. The nostrils
are small, and near the muzzle; the orbits are circular, and separated
by a space of more than their own diameter. In the upper jaw there is
a series of conical teeth on the maxillary and intermaxillary bones.
Those on the intermaxillaries are much larger than the others, and
have the aspect of canines or tusks. Within this outer series of
teeth, but implanted apparently in the same bones, there is as in
_Archegosaurus_ a second series of teeth, closely placed, or with
intervals equal to the diameter of one tooth. These inner teeth are
longer than the others, implanted in shallow sockets, to which they
are anchylosed, and have the dentine plicated, except toward the
point. A third group of teeth, blunt at the points, largely hollow in
the interior, and with the dentine quite simple, appears in detached
bones, which may represent the vomer. Only a part of this formidable
armature of the teeth appears in the skull, as the bones of the roof
of the mouth have been removed, adhering to the opposite side of
the matrix; but the fact of the occurrence of two sets of teeth was
ascertained by Professor Wyman, from the original specimens, and is
manifest in the fragment * * * while the other teeth, supposed to
be vomerine, appear in fragments which must, from their size and
collocation, have belonged to _Dendrerpeton_. It will be observed
that all of these teeth are anchylosed to the bone; and that those
of the vomer are thinly walled and simple, the outer series on the
maxillaries and intermaxillaries simple and flattened, while the inner
series of teeth are conical and plicated. In the lower jaw there was
a uniform series of conical teeth, not perceptibly enlarged toward
the front; at least this is the case in the only specimen at present
in my collection; which is, however, merely an imperfect cast in hard
sandstone.
"The scapular and sternal bones seem to have been well developed and
strong, but only portions of them are known. The fore limb of the
adult animal, including the toes, must have been 4 or 5 inches in
length, and is of massive proportions. The bones are hollow, and in
the case of the phalanges the bony walls were thin, so that they are
often found crushed flat. The humerus, however, was a strong bone,
with thick walls and a cancellated structure toward its extremities;
still, even these have sometimes yielded to the great pressure to
which they have been subjected. The cavity of the interior of the
limb-bones is usually filled with calc-spar stained with organic
matter, but showing no structure; and the inner side of the bony wall
is smooth, without any indications of cartilaginous matter lining it.
"The vertebræ, in the external aspect of their bodies, remind one of
those of fishes, expanding toward the extremities, and being deeply
hollowed by conical cavities, which appear even to meet in the center.
There is, however, a large and flattened neural spine. The vertebræ
are usually much crushed, and it is almost impossible to disengage
them from the stone. * * * in its long neural and hæmal spines,
reminds us of the caudal vertebræ of those batrachians and reptiles
which have tails flattened for swimming, and probably indicates that
this was the case with _Dendrerpeton_. The ribs are long and curved,
with an expanded head, near to which they are solid, but become
hollow toward the middle; and the distal extremities are flattened
and thin-walled. The posterior seems to have been not larger than
the anterior, perhaps smaller. The tibia is much flattened at the
extremity, as in some labyrinthodonts, and the foot must have been
broad, and probably suited for swimming or walking on soft mud, or
both. That the hind limb was adapted for walking is shown not merely
by the form of the bones, but also by that of the pelvis, the best
preserved specimen of which I have represented (208, pl. III, fig. 28).
"The external scales are thin, oblique-rhomboidal or elongated-oval,
marked with slight concentric lines, but otherwise smooth, and
having a thickened ridge or margin; in which they resemble those
of _Archegosaurus_, and also those of _Pholidogaster_. * * * The
microscopic structure of the scales is quite similar to that of the
other bones, and different from that of the scales of ganoid fishes
* * * ." #/
=Dendrerpeton oweni Dawson.=
Dawson, Quart. Jour. Geol. Soc. London, XVIII, p. 460.
Dawson, Air-breathers of the Coal Period, p. 32, 1863.
Dawson, Acadian Geology, 3d ed., p. 368.
Dawson, Phil. Trans. Roy. Soc. London, pt. II, p. 643, pl. 44, figs.
131, 138, 139, 1882.
A smaller species than the preceding. The form (plate 13) is fully
described by Dawson (Air-breathers of the Coal Period, p. 32, pl. IV,
1863) as follows:
"Among the reptilian remains found in erect trees at the South
Joggins, there have occurred several portions of skeletons which, from
their sculptural cranial bones, plicated teeth, and the forms of their
scales and limb-bones, I have referred to the genus _Dendrerpeton_,
but to individuals of much smaller size than the full-grown specimens
of _D. acadianum_. It did not occur to me to suppose that these were
specifically distinct from the larger individuals, until I observed
that bones of this kind, contained in the collections sent by me
to the Geological Society, or represented in the figures drawn to
illustrate one of my papers, were referred by Professor Owen, in his
notes on these specimens and figures, in the Journal of the Geological
Society, to the genus _Hylonomus_; which is quite distinct from
_Dendrerpeton_, as will be explained in sequel.
"I was thus induced to reexamine all the specimens in my collection
and the result has been to establish a strong probability that there
is in reality a second species of Dendrerpeton, smaller than _D.
acadianum_, and differing from it in several points. This species I
propose to name _D. oweni_. It differs from _D. acadianum_ in the
following particulars: (i) its much smaller size; (2) its long and
hooked teeth (it will be seen that these teeth differ very markedly
in their proportions and form from those of the larger species);(3)
the greater plication of the ivory in the intermaxillary teeth (in
_D. acadianum_ these teeth are, on the outside, simple almost to the
base, and plicated on the inner side, while in this species they are
plicated all around like the inner maxillary teeth);(4) the form of
the skull, which has the orbits larger in proportion, and is also
shorter and broader. On the other hand, when we have described the
species Hylonomus, it will be seen that this animal, except in size,
differs from them quite as widely as does _D. acadianum_.
"The distinctness of _D. oweni_ is further confirmed by the fact that
I possess small jaw-bones of _Dendrerpeton_, about the size of those
of this species, but having the teeth similar in form to those of the
larger species; these I suppose to have belonged to young individuals.
"On examining the figures (208, pl. IV) it will be seen that the
bones of the skull were corrugated as in the large _Dendrerpeton_,
but with a smaller pattern. The forms of the jaw-bones also, and
of the vertebræ, ribs, scapular bone, bones of the limbs, and bony
scales, are very similar, and indicate that in general form this
creature was not far removed from its larger relative. The bones
of the foot especially deserve attention. This is the most perfect
foot of _Dendrerpeton_ hitherto found; and I have enlarged it in the
figure (208) in order more distinctly to show its parts. It presents
three long toes with traces of a smaller one at each side, so that
there were probably five in all. If these toes be compared with the
footprints on the slab discovered by Dr. Harding, it will be seen that
they very closely correspond, though the toes of the present species
are much smaller. The footprints are precisely those which we may
suppose an animal of the size of _Dendrerpeton acadianum_ would have
made if, as the bones found render in every way probable, this larger
species had a foot similar to that of _D. oweni_. I suppose, for
this reason, that these footprints are really those of Dendrerpeton
acadianum and that this species continued to exist from the time of
the lower Coal Measures to the period when those higher beds of the
series, in which its bones are found at the Joggins, were deposited.
"The present species must have lived in the same places with its
larger relative, but may have differed somewhat in its habits. Its
longer and sharper teeth may have been better suited for devouring
worms, larvæ, or soft-skinned fishes, while those of the larger
_Dendrerpeton_ were better adapted to deal with the mailed ganoids of
the period, or with those smaller reptiles which were more or less
protected with bony or horny scales.
REMAINS OF SKIN AND HORNY SCALES.
"In one of my earliest explorations of the reptile-bearing stumps of
the Joggins, I observed on some of the surfaces patches of a shining
black substance, which on minute examination proved to be the remains
of cuticle, with horny scales and other appendages. The fragments
were preserved; but I found it impossible to determine with certainty
to which of the species whose bones occur with them they belonged,
or even to ascertain the precise relations of the several fragments
to each other. I therefore merely mentioned them in general terms,
and stated my belief that they may have belonged to the species of
_Hylonomus_.[E] More recently other specimens have been obtained, and
I have undertaken the detailed examination of the whole. I shall now
endeavor to describe the principal or most continuous fragments, and
afterward to consider the probabilities of their having belonged to
certain of the reptiles entombed with them. I do this here, rather
than under the titles of these several animals, on account of the
uncertainty which still rests on the assignment of certain portions
of this cuticle to the species in question, and which renders it more
convenient to consider these peculiar remains in one place and to
compare the different portions with each other.
[Footnote E: Journal of Geological Society, vol. XVI.]
"(1) One of my specimens is a flattened portion of cuticle 2.25
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. In contact with the upper part of this specimen there
were many fragments of the skull of _Dendrerpeton oweni_.
"(2) Another portion of the cuticle, similarly marked, appears to
preserve the form of the posterior part of the body and tail of the
animal, and also a mark representing the point of attachment of the
hind leg; near to which, and along the dorsal ridge, is a portion of
the skin covered with much smaller scales. This was found in close
proximity to a mass of bones of Dendrerpeton oweni, mingled with some
of _Hylonomus lyelli_.
"(3) A third and still larger surface of integument with similar
markings has upon it a number of vertebræ and detached bones of the
small reptile _Hylonomus wymani_, to be described in the sequel; for
which species, however, it would be much too large a covering.
"(4) Another well-preserved fragment, less than 2 inches in length,
exhibits very different markings. It is nearly covered with very small
imbricated scales, thicker than those on the specimens previously
described. On either side of what seems to have been the middle line
of the back, there is a series of pointed flat horny processes, which
probably formed a double spinous crest. Without these there are tufts
of strong bristles, and exteriorly to these last are rows of flat,
thick, horny plates, transversely wrinkled. Near to these was a row of
conical truncated tubercles. Sections of these appendages show them to
have been horny and attached to the cuticle. None of them have bony
structure.
"(5) Near this last portion of cuticle, and possibly belonging to
it, are pointed and probably membranous appendages, marked on each
side with rows of scales not overlapping and each with a pore in its
center. The manner in which these appendages are bent and wrinkled
shows that they must have been soft, except at the tips, which seem
to have been hard and horny, and they are arranged in series, as if
originally placed along the sides of the neck or abdomen, or both.
The use of these appendages is not easy to conjecture. They remind
us of the gular pouches of iguana, and of the lateral expansions of
some geckos and of the _Draco volans_. Possibly they formed lateral
parachutes, aiding the animal in moving over soft mud, or perhaps in
leaping and swimming.
"(6) Some other fragments appear to have belonged to a different
species from either of the foregoing. The best preserved specimen,
which is about 1 inch in length and half an inch in breadth, is
covered with very small imbricated scales. It is crossed by 6 or 7
obscure ridges, which both at the bottom and along a mesial line
project into points covered with larger scales. A row of large scales
with round pores connects these along the lower side. If, as seems
probable, this fragment belonged to the side of the trunk or tail,
it would perhaps indicate a division of the subcutaneous muscles
into an upper and lower band, as in the newts. A separate fragment
with transverse horny ridges and another with a longer lobe, similar
in structure to those above mentioned, may perhaps be referred to
the same animal. A larger patch of skin presents similar imbricated
scales, but without a mesial line, and with an edging of larger scales.
"Six species of reptiles have left their bones in the repositories
containing these remnants of cuticle. Of these, _Dendrerpeton
acadianum_, was an animal of too great size to have been clothed
with integument of this character and of such dimensions. Hylonomus
aciedentatus and _Hylerpeton dawsoni_ are each represented by only a
single specimen, and these did not occur in proximity to any of the
portions of cuticle, except that the appendages were found near a
specimen of the former. Of the three remaining species, _Dendrerpeton
oweni_, from its size, the number of specimens found, and the
juxtaposition of their bones to the fragments of cuticle, appears to
have the best claim to the integument included under Nos. 1, 2, and
3; and in this case, while the creature had its throat, and perhaps
its abdomen, armed with bony scales, its upper parts and tail, as well
as its limbs, had a uniform covering of small, thin imbricated horny
scales, in the manner of many modern reptiles.
"If the remaining portions of integument, Nos. 4 and 5, as would
seem likely, belonged to two species, both of smaller dimensions,
there would seem little reason to doubt that these were _Hylonomus
lyelli_ and _H. wymani_. In this case, both of these species must have
possessed a highly ornate covering of horny scales and appendages,
comparable with that of many of the modern lizards, while there
seems good reason to believe, as stated in a previous paper, that
they were in part protected by bony scales somewhat like those of
_Dendrerpeton_. These points, however, we shall consider more in
detail under the sections which refer to the species of _Hylonomus_.
"Before leaving these curious specimens of ancient skin, the most
ancient I suppose known to exist, it is of interest to observe that
the thicker portions, when broken across, have the aspect of jet, or
of pure shining coal, and thin slices, under the microscope, have
the same rich brown colour with that material, though rather more
translucent. When burned, fragments of the substance give a strong
flame, and a bituminous and ammoniacal odour. We have thus an example
of the production of coal from animal membrane, no doubt gelatinous
and horny in the first instance, but which has proved itself capable
of the same chemical changes that have been experienced by the
vegetable matter buried with it. In order that this substance should
be preserved in this way, it would be necessary that it should either
be kept dry and hard, or that it should be immediately buried in
matter impervious to air and kept moist. The latter conditions are
the more probable. The preservative qualities of the peaty vegetable
matter imbedded with it must be considered; and it is possible that
these hollow stumps, partly filled with fragments of _Sigillaria_
bark, may have formed natural tan-pits, in which animal membranes
would be preserved in a manner impossible in ordinary sediments. If
this were the case, we may yet find an entire reptile, preserved as a
flattened mummy, in one of these strange repositories."
=Genus PLATYSTEGOS Dawson, 1895.=
Dawson, Proc. and Trans. Roy. Soc. Canada, 1895, XII, p. 77 (sec. IV).
Type: _Platystegos loricatum_ Dawson.
Dawson's description is as follows:
"Head broad and short, orbits very large, cranial bones deeply
sculptured; teeth strongly plicated and curved, with sharp edges at
apices, especially the inner palatal teeth, which are very large. Many
minute teeth on the vomerine bones; vertebræ ossified, biconcave; limb
bones imperfectly ossified, short; lower surface protected with a
thoracic plate and thick, densely imbricated bony scales in transverse
rows; body above with thin, round scales, concentrically marked."
=Platystegos loricatum Dawson.=
Dawson, Proc. and Trans. Roy. Soc. Canada, XII, p. 77, 1895.
Dawson describes the species:
"Head about 8 cm. long; when flattened 9 cm. broad across parietal
foramen; squamosal and temporal bones projecting backwards in points
much behind the condyles; parietal foramen small, orbits large; length
of longest tooth seen 7 mm.; cranial bones closely and deeply pitted;
humerus with very thin bony walls, cartilaginous within, 3.5 cm. long."
Erect tree, coal formation, at the South Joggins; collected by P. W.
McNaughton. Type in Peter Redpath Museum at McGill University. Dawson
regarded the form as of uncertain relationship.