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 scapula of the present form is exceptional in its shape. It resembles
an asymmetrical pyramid, the anterior side of the lower edge of the bone
being contracted so that the anterior edge of the element is arcuate. Its
top is very thin and possibly terminated in a broad cartilage. The lower
end is thick and heavy and the articular surface is, apparently, well
formed, though somewhat obscured.
The element identified as a clavicle is lying on its edge and has the
proportions of the clavicle of _Mazonerpeton costatum_. The exterior
edge is somewhat rounded and small. A portion of another element which I
suppose to represent the coracoid lies alongside the humerus, although its
form is quite obscured. (Plate 3, fig. 3.)
The humerus has a remarkably well-formed head. In perfection of formation
it corresponds well with that of the higher reptiles. This surface can
even be divided into an anterior and a posterior articulation. The element
projects posteriorly for the distance of 1 mm. from the surface of the
shaft. The shaft immediately below the head is somewhat flattened and has
an ovoid section. Further on it becomes flattened, a part of which is
probably due to pressure during fossilization.
The elements of the forearm are both preserved and are approximately equal
in size. They are remarkable in that they exceed the humerus in length,
although they are not so heavy as that element. They are greatly elongate
and slender, with the middle of the shaft only moderately contracted. The
articular surfaces are well formed and both bones were hollow, as was
also, apparently, the humerus. The ulna may be represented by the most
posterior of the two elements, though the relations of the elements may
have been reversed (fig. 15, D).
The base of the left wing of an orthopterous insect possibly allied to
_Paolia gurleyi_ Scudder lies between the radius and ulna. The nodule also
contains impressions of plants, a portion of a frond of a _Neuropteris_
and the impression of one of the Cordaites. Lying next the radius is a
slender elongate element which may be a rib or a portion of a metacarpal.
If a rib, it indicates that the animal belongs among the Branchiosauria.
The fragment is only half as long as the radius and is entirely too
obscure to base any conclusions. The other characters of the specimen
point quite strongly to its microsaurian affinities.
The structure of the articular surfaces of the limb bones alone would
indicate the microsaurian relationship of _Erpetobrachium_. It may be
provisionally associated in the family Molgophidæ with such forms as
_Molgophis brevicostatus_ Cope, _Molgophis_ (_Pleuroptyx_) _clavatus_
Cope, and _Molgophis macrurus_ Cope from the Coal Measures of Linton, Ohio.
Measurements of the Type.
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