The Coal Measures Amphibia of North America

by Roy Lee Moodie

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.

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.