THE MICROSAURIAN FAMILY AMPHIBAMIDÆ, FROM THE COAL MEASURES OF MAZON
CREEK, ILLINOIS.
=Family AMPHIBAMIDÆ new family.=
Small, lizard-like, terrestrial or semi-aquatic, megacephalic
microsaurians, known from 3 species. The family characters are the
huge size of the head as compared to the body, the short, stumpy body
with about 25 short dorsal vertebræ, a very short tail, phalanges
clawed, pubis of calcified cartilage, sclerotic plates in the orbit to
the number of 29 or 30 in each, ventral armature well developed. Teeth
anisodont, sharp, conical, non-striate.
Two genera are associated in this family: _Amphibamus grandiceps_ Cope,
known from three nearly complete skeletons; _A. thoracatus_ Moodie, known
from a single incomplete skeleton; _Cephalerpeton ventriarmatum_ Moodie,
anterior portion of body and skull. The species are all from the Mazon
Creek shales and the family seems unrepresented elsewhere. It may be
necessary to compare the Amphibamidæ with the Hylonomidæ when the latter
group is better known, but in the light of our present knowledge the two
families are distinct.
The genera may be distinguished as follows:
I. Size small, less than 3 inches in total length, skull with deeply
incised tympanic notches (ear-slits) _Amphibamus_
II. Size relatively large, body-length 6 inches or more, teeth
distinctly anisodont, skull with nearly even posterior table,
limbs very long, ventral armature highly developed _Cephalerpeton_
=Genus AMPHIBAMUS Cope, 1865.=
Cope, Proc. Phila. Acad. Nat. Sci., 1865, pp. 134-137. Geol. Surv.
Ills., 11, pp. 135-141, pl. xxxii, 1 text-fig.
Hay, Proc. Am. Phil. Soc., XXXIX, p. 120, 1900.
Moodie, Jour. Geol., XVII, p. 81, fig. 24, 1909.
Type: _Amphibamus grandiceps_ Cope.
The publication of the type species of this genus began the researches
of Professor Cope on the extinct Amphibia of North America, which he
continued for so many years with such excellent results (105-177). The
description was based on a single specimen (plate 3, fig. 7) belonging
to Mr. Joseph Evans, of Morris, Illinois, who loaned it to Dr. Worthen
for the Illinois Geological State Survey (107), in order that it might
be described. The type has been destroyed by fire; so I am informed by
Mr. L. E. Daniels, of Rolling Prairie, Indiana. There are two other known
specimens of the species. One is in the collection of Mr. Daniels and the
other No. 794, of Yale University Museum.
This genus may be clearly separated from all the other microsaurians by
characters which are peculiar to the form. Among these may be mentioned
the possession of sclerotic plates in the eyes; the large size of the
orbits in comparison with the dimensions of the skull; the short, broad
form of the body; the very short tail; the possession of a calcified
cartilaginous pubis; clawed phalanges; presacrals 22. The character which
places the genus distinctly in the Microsauria is the possession of long,
slender, curved ribs, first detected on Mr. Daniels's specimen (plate 14,
figs. 1, 2), by Dr. Hay (316). Its stegocephalian characters are evident
in every particular of its anatomy the roofed skull, the arrangement of
the cranial elements, the presence of a well-developed ventral armature,
and the digital formula (4 for the hand and 5 for the foot).
The genus _Amphibamus_ was regarded by Cope as a representative of a new
order of vertebrates which he called (105) Xenorachia. He later (123)
abandoned this, however. Fritsch (251), Zittel (642), and others regarded
_Amphibamus_ as a branchiosaurian. The exact position of the form was
uncertain until 1900, when Dr. Hay (316) described the long, curved ribs
and suggested its place among the Microsauria. He, however (Cat. Foss.
Vert., p. 410), made the mistake of including the branchiosaurian family
Protritonidæ, under Microsauria, thus confusing the subject further. The
genus (462) has not the slightest relationship with the Branchiosauria.
=Amphibamus grandiceps Cope.=
Cope, Proc. Phila. Acad. Nat. Sci., pp. 134-137, 1865; Geol. Surv.
Ills., 11, pp. 135-141, pl. xxxii, and 1 woodcut, 1866.
Hay, Proc. Am. Phil. Soc., XXXIX, p. 120, 1900.
Moodie, Jour. Geol., XVII, No. 1, p. 82, fig. 24, 1909.
Moodie, Kan. Univ. Sci. Bull., VI, No. 2, pp. 343-349, pl. 1, figs. 1
and 2; pl. 5, fig. 3; pl. 7, fig. 1; pl. 11, 12, 13, 1912.
Type: Specimen has been destroyed. There is an excellent specimen (plate
4, figs. 5. 6), No. 794 (1234), in Yale University Museum, and another
nearly as good in the possession of Mr. L. E. Daniels, of Rolling Prairie,
Indiana.
Horizon and locality: Mazon Creek shales, near Morris, Illinois.
The form of the skull of _Amphibamus grandiceps_ Cope is not unlike that
of _Tuditanus minimus_ Moodie (462) from the Linton, Ohio, beds, but
it is less acuminate than in that form. The large size of the orbits
is especially striking. The shape of the skull is triangular, with
concavities in the posterior table which correspond to the ear-slits so
characteristic of _Metoposaurus_ (242) from the Keuper of Germany. The
narrowed posterior table of the skull is truncate, as in several other
genera of Microsauria, notably _Tuditanus_ and _Saurerpeton_. In structure
the skull differs but little from many of the other Carboniferous forms,
but the arrangement of the elements of the skull is more regular than in
other genera.
The premaxillaries are very small elements in the anterior tip of the
skull. They border the nares. The skull is rather peculiar among the
Microsauria in the possession of a distinct lacrimal. I have detected
this element in the cranium of _Stegops divaricata_ Cope. As here defined
the lacrimal is triangular, with its posterior border formed exclusively
by the prefrontal. Its other relations are the normal ones. The nasal
is elongate, with the usual relations of that element. The frontal
is slightly longer and broader than the nasal. It apparently forms a
portion of the inner border of the orbit. The parietal foramen lies in
the anterior fourth of the parietal, a rather unusual position for this
structure. The parietals, as in so many of the Microsauria, together
form the largest element of the skull and are roughly a triangular area
in the postero-median portion of the skull. The postparietal and the
tabulare are clearly distinguishable and they have the usual relations
for those elements. The maxillary, jugal, and quadratojugal together form
the greater part of the maxillary border. The postero-lateral angle of
the skull is, as visual, formed by the squamosal. The orbit is bounded
posteriorly by the postorbital and the postfrontal, which include in the
angle between them the quadrangular squamosal. The orbit is especially
remarkable for its size as compared with the dimensions of the skull,
being without a parallel among other known Microsauria. Around the border
of the orbit in the specimen Cope studied (105) there were found 14
quadrangular plates which he called "superciliary plates." Hay (316) was
inclined to regard them as sclerotic plates. In the Yale Museum specimen
(plate 4, figs. 5, 6) there are 20 of these plates, and there seems to be
no doubt that they are sclerotic elements. In the restoration (fig. 26) 29
sclerotic plates are given, but there is no assurance that this number is
the exact one. They may also have been slightly larger, but not as large
as in Branchiosaurus.
[Illustration: Fig. 26. Restoration of body outline and skeleton of
_Amphibamus grandiceps_ Cope, from Mazon Creek, Illinois, shales.
Restoration is based on complete specimens of the species and on Cope's
drawing. Form of body is indicated in one specimen, that in possession of
Mr. Daniels. × 1.5.
Skull: _pmx_, premaxilla; _n_, nasal; _fr_, frontal; _par_, parietal;
_la_, lacrimal; _pf_, prefrontal; _pof_, postfrontal; _po_,
postorbital; _pp_, postparietal; _spt_, supratemporal; _mx_,
maxilla; _j_, jugal; _qj_, quadratojugal; _sq_, squamosal; _tab_,
tabulare.
Skeleton: _ic_, interclavicle; _cl_, clavicle; _sc_, scapula; _h_,
humerus; _r-u_, radius, ulna; _r_, carpus; _pu_, pubis; _il_,
ilium; _f_, femur; _t_, tibia; _fb_, fibula; _ts_, tarsus; _x_,
ischium.
]
The vertebral column is preserved nearly entire in the Daniels specimen
and quite entire (478) in the Yale specimen. Cope, in his study of the
type (105, 107), thought there could be no more than 13 presacrals, but
the specimen was poorly preserved and indecisive on this point. Dr. Hay
(316) was inclined to the opinion that there were less than 20. The Yale
specimen shows 22 centra, which are elongate, hour-glass-shaped bodies,
with the neural spine a long, low crest running the entire length of the
centrum, with a median elevation, so that in lateral view the spine would
be triangular in form. The body of the centrum is expanded laterally into
a diapophysis which extends anteriorly. The posterior vertebræ, at least,
had the notochord largely persistent. The osseous part of the vertebra
seems to have been but a thin shell, and the structure of the zygapophyses
can not be determined. That they were dorsal in position is, however,
evident from several vertebræ. The points of these structures project
laterally. The tail is short and the caudal vertebræ weakly developed.
There are distinct impressions of at least 12 pairs of ribs in the Daniels
specimen. They are long, slender, and curved, and there is no definite
assurance that there were as many ribs as are indicated (fig. 26) in the
restoration (462). The ribs are intercentral (469) and probably occupied
the full length of the vertebral column. There may have been as many as
indicated in the restoration.
One of the most interesting features of the Yale specimen is the
preservation of a small patch of skin, evidently from the back, lying to
one side near the head, measuring 5 mm. in length by 3 mm. in width. The
fragment shows the skin to be of tuberculated scales, 4 of which occupy
the length of 1 mm. The scales are somewhat hexagonal, almost rounded, and
were relatively quite thick. They lie in a close mosaic (fig. 27).
[Illustration: Fig. 27. Skeleton of _Amphibamus grandiceps_ Cope. × 1.4.
_c_, carpus; _cl_, clavicle; _cr_, caudal rib; _cv_, caudal vertebra; _f_,
femur; _h_, humerus: _il_, ilium; _s_, skin: _or_, orbit: _r_, radius;
_ul_, ulna; _sc_, scapula; _sp_, sclerotic plates; _t_, tibia and fibula;
_ts_, tarsus; _vs_, ventral scutellæ. Specimen No. 794, Yale University
Museum.]
The Yale specimen has, very well preserved, a portion of the ventral
scutellæ, of the throat, chest, and belly. The arrangement of the plates
on the throat and chest is almost exactly the reverse of what Credner has
described (190) for _Branchiosaurus amblystomus_ Cred. On the throat, in
the present form, the chevron points anteriorly, and it is the anterior
prolongation of the belly scutes with the postero-lateral projection of
the gular scutes which form the chest and arm scutellation. The belly
chevrons point anteriorly, as in _Branchiosaurus_, the rods formed by the
scutes being straight and not curved as in _Branchiosaurus_. The entire
ventral armature preserved is displaced to the left of the animal and only
the anterior portion is preserved.
The pectoral girdle is only partially known. The scapula is
crescent-shaped. The other elements are indicated only by fragments and
nothing is known of their form.
The arm elements are nearly all known. The humerus is slender and expanded
at the ends, with its articular surfaces well developed. The separate
radius and ulna are of approximately the same size and length. The
carpus is unossified. The complete phalangeal formula for the hand of
_Amphibamus_ is unknown. The third digit seems to have 4 elements. The
formula 2-2-3-2 has been suggested (462).
The pelvis is very satisfactorily known. The ilium is a long, slender,
straight rod, with expanded ends. The ischium is shown on both sides of
the vertebral column in the Yale specimen. Its form is almost identical
with that of _Paleohatteria longicaudata_ Credner, from the Rothliegenden
of Saxony. The ischia are apparently approximate in the median line,
though this character is somewhat obscured by the impression of the
caudal vertebræ. Their relation with the ilium, other than that they
were posterior to it, is uncertain. The pubis is, apparently, calcified
cartilage. It is a squarish plate, somewhat corrugated, lying anterior
to the ilium in the Daniels specimen. The elements of the pelvis were
undoubtedly hung loosely in the flesh, as in modern salamanders, since
there is no indication of articular surfaces.
The hind limb is well known, the type having a nearly complete leg with
the foot. The Daniels and the Yale specimens supplement and substantiate
the type. The femur is longer than the humerus, but more slender, with its
articular surfaces about as well developed as in the humerus. The element
is a simple rod of bone without muscular crests of any kind. The tibia
and fibula are, likewise, slender separate rods of bone. The tarsus is
unossified. The phalangeal formula is 2-2-3-4-3, and is fairly definite.
[Illustration: Fig. 28. Restoration of probable appearance of _Amphibamus
grandiceps_ Cope on the basis of the material described herewith. × 1.5.]
In the type specimen the matrix in the orbit was blackened as if by the
_pigmentum nigrum_ of the choroid. The same has been noticed in other
specimens. Professor Cope thought this indicated that the animal was
nocturnal.
There are many characters in _Amphibamus_ which seem to approximate the
reptilian type of structure. Among these may be mentioned the character of
the articular surfaces of the limb bones, the intercentral position of the
ribs, the incipient double-headedness and the curvature of the ribs, the
presence of a cartilaginous calcified pubis, the length of the limbs, and
the clawed character of the phalanges.
_Amphibamus_ was a low, flat, short, and undoubtedly a creeping, crawling
animal, possibly spending a portion of its time in the water; but it
could not have been a swimmer. It was one of nature's first attempts at
constructing a land vertebrate.
Measurements of Amphibamus grandiceps Cope.
Collection of Mr. L. E. Daniels, of Rolling Prairie, Indiana:
mm.
Entire length of specimen 62
Posterior width of head 15
Length of head 15
Posterior height of skull 3
Length of orbit 5
Width of orbit 3.5
Interorbital width 4
Width of skull in front of orbits 11
Width of skull just back of orbits 16
Length of presacral region of the
vertebral column 30
Length of tail 13
Length of fore limb 13.5
Length of humerus 4
Length of radius and ulna 3
Length of right hand as preserved 3.5
Length of rib along curve 5.5
Length of hind limb 17
Length of ilium 4
Length of vertebral centrum 1.75
Length of portion of scapula (?) preserved 4.5
Length of foot 6.5
Width of impression of body midway 16
No. 794 (1234), Yale University Museum:
mm.
Length of skeleton 67
Length of skull 15
Posterior width of skull 15
Depth of tympanic notch 4
Width of tympanic notch 6
Long diameter of the orbit 7
Transverse diameter of the orbit 5.5
Interorbital width 4.5
Diameter of pineal foramen .75
Length of cervical series of vertebræ 9
Length of dorsal series 35
Length of caudal series 13
Length of a centrum of the dorsal series 1.5
Length of dorsal rib 3.5
Length of arm 20
Length of humerus 7
Length of radius and ulna 4
Width of carpal space 3
Length of third digit 5
Length of leg 25
Length of ilium 3
Length of femur 9
Length of tibia and fibula 5
Length of carpal space 4
Length of 1st digit 3
Length of 2d digit 4.5
Length of 4th digit 7
3 ventral scutellæ in 1 mm.
=Amphibamus thoracatus Moodie.=
Moodie, Proc. U. S. Nat. Mus., 40, pp. 431-433, fig. 2, 1911.
Moodie, Kans. Univ. Sci. Bull., VI, No. 2, pp. 347-349, pl. 5, fig. 2,
1912.
Type: Specimen No. 4306, U. S. National Museum.
Horizon and locality: Mazon Creek shales, near Morris, Illinois.
The type is a part of the collection of Mr. R. D. Lacoe, in the U. S.
National Museum. The fossil is very poorly preserved, but the remains are
to be seen on both halves of the nodule, so that considerable can be made
out as to its structure.
The chief diagnostic characters which will at once distinguish the species
are the elongate arm, large interclavicle, shape of the vertebra, and
triangular skull.
The portions of the animal which are preserved are the impression of
the skull with one orbit, the right humerus and radius with portions of
others, and traces of ventral scutellæ. These remains are so intermingled
with the remains of plants that it has been quite difficult to distinguish
bone impression from plants. This, however, has been done by whitening the
fossils with ammonium chloride, when the texture of the fossils serves
to distinguish the one from the other. Parts of the plants have been
converted into galena and kaolin, as have also parts of the bones, so the
task has been rendered doubly difficult. There can be no doubt, however,
that the observations recorded below are correct. The position of the
arm in relation to the pectoral girdle and the position of the girdle in
relation to the skull impression first called attention to the possible
presence of a fossil amphibian.
There is little to be said of the skull. It is merely an impression in the
nodule. It is triangular in form, with the snout an acute angle. The angle
is, however, exaggerated by the compression to which the fossil has been
subjected. The right side of the skull lies over a portion of some plant.
The animal is preserved on its back, so that this gives a good opportunity
for the study of the pectoral girdle, which is partially preserved.
The interclavicle is very large and from it the species has been given
its specific name (_thoracatus_--armed with a breast plate). It is an
exaggerated =T=, with the stem very short with its anterior margin
curved, and ending in a rather sharp, elongate point. The interclavicle
recalls, in a measure, the same element of the Branchiosauria, although
it is much more expanded anteriorly and has a shorter spine. In these
respects it resembles more nearly a reptilian interclavicle (fig. 14 B).
The clavicle is of the simple triangular shape so characteristic of the
Microsauria. It is somewhat displaced backward and its inner margin is
slightly obscured. The humerus is elongate, apparently cylindrical, and
with expanded ends, resembling very closely the humerus of _Amphibamus
grandiceps_, although its proportions are much greater than in that
species. Its length is almost equal to the length of the skull, while in
_A. grandiceps_ the length of the humerus is only half that of the skull.
The radius (ulna?) resembles in its general proportions those of the
humerus. It is a more elongate, slender, lighter bone. The impression of
the other bone of the forearm is obscured.
A portion of a single vertebral centrum from the posterior part of the
dorsal series is preserved. It is apparently amphicœlous; its width is
nearly half greater than its length.
Measurements of the Type of Amphibamus thoracatus Moodie.
(No. 4306, U. S. National Museum.)
mm.
Length of entire specimen, as preserved 60
Length of skull impression 18
Greatest width of same 15.5
Long diameter of right orbit 4
Transverse diameter of same 3
Transverse width of interclavicle 14
Long diameter of same 7(?)
Long diameter of clavicle 9
Greatest transverse diameter 3
Length of humerus 10
Greatest diameter of same 4
Least diameter of same 1.5
Length of radius (ulna?) 11
Length of vertebral centrum 2
Width of same 3
=Genus CEPHALERPETON Moodie.=
Moodie, Kans. Univ. Sci. Bull., VI, No. 2, p. 340, 1912.
Type: _Cephalerpeton ventriarmatum_ Moodie.
This genus is founded on remains of a nearly entire individual of a
relatively large microsaurian from the Mazon Creek shales. The genus is
most immediately related to the Amphibamidæ, of which two species are
already known, _Amphibamus grandiceps_ Cope and _A. thoracatus_ Moodie.
The present genus differs from these species in many respects, notably
in size. The skull in _Cephalerpeton_ is nearly as long as half the
entire body of _Amphibamus grandiceps_ Cope, inclusive of the tail. Other
structural differences are the anisodont teeth, the large size and the
more median position of the orbits, and the absence of the posterior
tympanic notch in _Cephalerpeton_. The form of the skull recalls that
of _Melanerpeton_ and _Pelosaurus_ (190) of Europe, but those genera
are branchiosaurian, while the present form, from the structure of the
vertebræ and the long, curved ribs, is an undoubted microsaurian. Nothing
like it occurs in any of the amphibian faunas thus far made known. It is
most nearly approached by a member of the genus _Erpetosaurus_, but from
this genus the present form is readily distinguished by the smooth skull
bones, the absence of a posterior table to the skull, and the presence of
a highly developed ventral armature. The interorbital width is less than
the transverse diameter of the orbit.
[Illustration: MOODIE PLATE 18
1. Type specimen of _Erpelosaurus sculptilis_ Moodie, from the
Cannelton Shales of Pennsylvania. Original in the University of
Chicago, Walker Museum.
2. Skeletal elements of _Eryops_ sp. indet., from the Pittsburgh Red
Shale at Pitcairn, Pennsylvania. _a_=nearly complete vertebra;
_b_ and _c_=ribs; _d_=pleurocentrum; _f_=neural arch and spine.
Originals in the Carnegie Museum at Pittsburgh. After Case.
3. Photograph of amphibian footprints, _Dromopus aduncus_ Branson,
from the Mississippian shales of Giles County, Virginia. × 1/3.
Courtesy of Dr. Branson. Original in the Museum at Oberlin
College.
4. Photograph of type of _Thinopus antiquus_ Marsh, the amphibian
footprint from the Devonian of Pennsylvania. × 1/4. Courtesy of
Dr. Lull. Original No. 784, Vale University Museum.
]
=Cephalerpeton ventriarmatum Moodie.=
Moodie, Kans. Univ. Sci. Bull., VII, No. 2, pp, 350-352, pl. 1, fig.
4; pl. 7, fig. 2, 1912.
Type: Specimen No. 796, of Yale University Museum.
Horizon and locality: Collected at Mazon Creek in 1871, near Morris,
Illinois.
The remains on which the present species is based consist of an almost
entire skull, 26 consecutive vertebræ, both fore limbs, 20 ribs preserved
on the right side of the body, and a portion of the ventral armature
(plate 4, fig. 4).
The skull is very broad posteriorly, its width being one-third greater
than its length, with due allowance for crushing. A pineal foramen is
not preserved. The sutures bounding the premaxillaries, the maxillæ, the
nasals, the prefrontals, the frontals, a portion of the parietals, the
squamosal, the supratemporal, the quadratojugal, and the quadrate (?) are
fairly well preserved. The arrangement of these elements can be discerned
by reference to figure 29. The prefrontals are unusually large and are
triangular in shape. The supratemporal is also quite large. The surface of
the skull bones is smooth and there is nowhere an indication of sculpture.
[Illustration: Fig. 29. Skeleton of _Cephalerpeton ventriarmatum_ Moodie.
× 1.
_pf_, prefrontal; _cl_, clavicle; _m_, mandible; _h_, humerus; _j_, jugal;
_mx_, maxilla; _or_, orbit; _ph_, phalanges of hand; _par_; parietal;
_po_, postorbital; _r_, radius; _sp_, sclerotic plates; _u_, ulna; _vs_,
ventral scutellæ.]
Portions of 4 sclerotic plates are preserved in the right orbit. These
measure 0.5 by 0.75 mm. The orbits are large and the interorbital space is
less than the transverse diameter of the orbit. Thirteen teeth, apparently
pleurodont, are preserved on the left maxilla. They are short, sharply
pointed, smooth, and unequal. The first 2 left maxillary teeth from the
anterior end are short; then follows a tooth which is one-third longer
than these two; the fourth tooth is somewhat shorter than the third; the
fifth and sixth are still shorter and are practically equal in size,
though somewhat larger than the first two.
The right mandible is preserved almost entire, though so badly eroded that
little can be said of its structure. Impressions of 12 teeth are present
on the mandible and all are, apparently, equal. The cotylus seems to have
been far posterior and an angle of the mandible projected slightly back of
the skull.
There remain only a few indefinite impressions of the cervical vertebræ.
The union of the skull with the vertebral column is obscured and lost.
Impressions of the dorsal vertebræ are well preserved, and wax molds
made from these show the structure of the dorsal vertebræ surprisingly
well. They are long and cylindrical, with the median portions slightly
constricted by a deep pit on each side of the low neural ridge, which
takes the form observed in _Thyrsidium_, _Molgophis_, _Phlegethontia_,
_Dolichosoma_ (fig. 8) and other genera. The vertebræ are strongly
amphicœlous and the notochord was probably persistent. The sides of the
vertebræ are smooth.
The ribs are all intercentral in position; the anterior ones very broad
near the base, recalling the broadly expanded ribs described by Schwarz
(540) for _Scincosaurus_, _Ptyonius_, _Thyrsidium_, and other genera.
Posteriorly the ribs become slender and cylindrical. They are all rather
long and distinctly curved, with probably a cartilaginous tip.
There is preserved a single element of the right side of the pectoral
girdle. This is, I think, the coracoid, an element which has hitherto
escaped observation among the American Microsauria. It is long and
spatulate at both ends, with the median portion apparently almost
cylindrical, not unlike that described by Credner (181) for the coracoid
of _Branchiosaurus_, save that the lower end of the branchiosaurian
coracoid is acuminate. In the present form it is spatulate. Its
relations with the other elements of the pectoral girdle have never been
satisfactorily determined.
The fore limbs are both partially preserved. The humerus of the right
side is complete. It is greatly elongated for a microsaurian. The form
of the element is not unlike that of a lizard, with the lower end of the
bone spatulate and endochondrium well developed. Very little difference
can be seen between the form of the arm bones, which represent the radius
and ulna. They are both elongated, with constricted median portion and
expanded truncate ends. The carpus is unossified and the cartilage has
left no trace of the elements.
The right hand has two metacarpals preserved, which are fully half as long
as the radius and ulna. They are separated some little distance from the
ends of these elements, though this may be due to post-mortem shifting.
The carpus may, however, have been broad. On the left side are preserved
portions of the humerus, radius, ulna, and 3 metacarpals, lying close to
the vertebral column. The carpal space is not so large on the left as on
the right. The ventral armature is well preserved in a narrow patch about
an inch in length. The chevron-shaped rods are quite large, there being 2
of them in 1 mm.
Measurements.
mm.
Entire length of fossil 98
Length of skull 22
Width across base of skull 28
Long diameter of eye 10.5
Transverse diameter of eye 8
Interorbital space 4
Length of mandible 26
Depth of mandible at coronoidal region 3.5
Depth of dentary 2
Length of long tooth 2
Diameter of long tooth at base .5
Length of preserved portion of vertebral column 64
Length of a centrum 3
Median width of a centrum 1.5
Length of rib 6.5
Width of rib at base .33
Length of coracoid 5
Width of coracoid at anterior end 2.5
Length of carpal space 5
Length of humerus 18
Width of shaft 1
Distal width of humerus 4
Length of radius and ulna 10.5
Length of metacarpal 6
Length of ventral armature preserved 24
Number of rods in length of 5 mm 10
[Illustration: MOODIE PLATE 19
Type specimen of _Ctenerpeton alveolatum_ Cope, from the Coal Measures of
Ohio. × 1.33. Original in U. S. National Museum.]
[Illustration: MOODIE PLATE 20
1. Skull of _Erpetosaurus minutus_ Moodie, from the Cannelton slates
of Pennsylvania. Original in U. S. National Museum. Enlarged ×
3.3.
2. Skull and anterior part of body of _Ptyonius pectinatus_ Cope,
from the Coal Measures of Linton, Ohio. Original in U. S.
National Museum. × 1.
3. Skeleton of Eosauravus copei Williston, from the Coal Measures of
Linton. Ohio. "The oldest known reptile from North America" and
closely related structurally to the Microsauria. Original in U.
S. National Museum. × 1.
4. Part of the ventral scutellation and ribs of Sauropleura digitata
Cope, from the Coal Measures of Linton. Ohio. Original in
American Museum of Natural History. × 1.
]