The Coal Measures Amphibia of North AmericaMoodie, Roy Lee
Science
The Coal Measures Amphibia of North America
Moodie, Roy Lee
Amphibians, Fossil -- North America; Paleontology -- Carboniferous; Paleontology -- North America
The remains consist of the following elements: an incomplete skull; nearly
the entire vertebral column, consisting of cervical, dorsal, sacral, and
caudal vertebræ, 36 in number; several ribs preserved on each side of
the vertebral column; a portion of the ventral armature; the scapulæ; a
clavicle; the interclavicle; both humeri; the radius and ulna of one side
and the ulna of the other; portions of both hands; the ilium of the right
side; both femora, and a partial impression of the left tibia.
The skull is, unfortunately, very poorly preserved. Enough remains,
however, to determine the essential characters. The skull bones, unlike
any other American branchiosaurian, have an ornamentation consisting of
sharp pits and elevations which in places have a quincuncial arrangement
and in others take the form of definite lines of pits or tubercles similar
to the condition found in many of the Microsauria. The orbits are large
and are situated back of the median transverse line of the skull. They
are almost circular in form and contain 6 elongated sclerotic plates very
closely arranged around the borders of the right orbit. The plates are
twice as long as wide. The interorbital width is 1.25 times the transverse
diameter of the orbit.
Not many of the sutures of the skull are discernible. Portions of
the frontals, the nasals, the prefrontals, the parietals, and the
supratemporals can be identified. Their arrangement is shown in figure
14_a_. There is a decided posterior table to the skull, with truncate
posterior border. The tympanic notch is shallow, with its outer border not
so well protected as in _Branchiosaurus_.
The cervical vertebræ are incomplete, but their number was 4 or 5, as in
_Micrerpeton_. The structure of the dorsal vertebræ is also uncertain,
although the shape can be discerned. The vertebræ are short and thick,
very unlike the long, cylindrical vertebræ of _Cephalerpeton_. The heavy
transverse process is quite evident on the best preserved vertebræ. This
process recalls that described by Credner for the Saxony Branchiosauria.
Several of the vertebræ show the articulation of the ribs with this
process. The ribs of the caudal region recall very strongly those of
_Branchiosaurus_. They are quite heavy in the anterior caudal region and
then diminish rather rapidly to the point where the tail is broken and
lost.
The ventral armature is represented by a patch of chevron rods 21 mm. in
length. The rods take a very peculiar form, being short crescentic bundles
of fine rods, hair-like in appearance. In one of these bundles I count 5
smaller rods. The bundles are arranged in rows similar to the pattern so
characteristic of the Carboniferous Amphibia, as described elsewhere. The
patch of ventral armature preserved belongs to the abdominal region. A
single row of the crescentic bundles measures 11 mm.
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