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 vertebral column is represented by a ridge showing along the median
plane of the specimen. Its characters can not be ascertained. There are a
few evidences of ribs. They represent long, slender, non-alate elements,
their mode of articulation with the vertebræ being obscured by the
plate-like ventral armature which covered the abdomen of the animal.
The pectoral girdle is represented by the remains of three elements which
are interpreted as being the interclavicle and the two clavicles. The
interclavicle is broad and is rounded posteriorly. There is no evidence
of the usual acumination posteriorly. The element is nearly as wide as
long. There is a prominent longitudinal keel on the ventral surface of
the interclavicle and radiating lines which may indicate the courses of
blood-vessels or nerves or may be the ornamentations of the element,
probably the latter. The clavicle has the usual microsaurian form. It has
three points and is truncate exteriorly. It is ornamented with radiating
grooves of a shallow and not strongly pronounced character. There is no
evidence of the coarse sculpture of the later forms. If the scapula is
represented it is merely by an indeterminate fragment insufficient for
description.
The pectoral limbs are preserved nearly entire. The left fore limb lacks
only a few phalangeal bones, and these were preserved with the remainder
of the skeleton but were lost in the mining process. The humerus is an
extraordinary element on account of its robust dimensions. It is very
stoutly built and represents a powerful limb. It is expanded at each
extremity and the width of its shaft is about equal to one-fourth of its
length. The ulna and radius present the same characters as the humerus,
_i.e._, in being robust, with stout shaft and expanded ends. The ulna
is slightly longer than the radius and has an expanded upper end. The
radius is short and does not have the proximal expansion. The carpus was
cartilaginous. Its position is represented by a blank space on the coal.
There are 4 digits preserved and in all probability this was the entire
number. The metacarpals are elongate and expanded at the extremities. The
first and second digits are represented nearly complete. The first digit
is extremely interesting in the possession of a claw-like terminal phalanx
which much resembles that of some lizards. There are 3 phalanges in the
first digit and 4 in the second. The phalangeal formula may have been
3-4-4?.
The ventral scutellation of this species is of an unusual character. It
consists of broad, imbricated scutes which are in a single piece and which
are arranged in the usual chevron pattern. The scutes were, apparently,
broadest in the middle and tapered somewhat at the extremities. This
character alone is sufficient for separating the genus from that of any
other known form.
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