The species was about as large as an adult Florida alligator, and probably exceeded or at least equaled in size any of the Carboniferous Amphibia. The following account is taken directly from Professor Cope's "Batrachia of the Ohio Coal Measures" ([123]). The description has been verified from an examination of the type material.
"The teeth are rather distantly grooved for some distance above the base. They are of different sizes; the smaller are compressed, and with fore and aft cutting edges. The external surface of the dentary bone is marked with short oblique grooves along its middle region; above these are grooves which inosculate, forming a figure like an open net dragged in the long direction.
"Excepting the grooves the teeth are smooth. The smaller ones are close together and their crowns are curved backwards; the larger ones are at more remote intervals; both have enlarged bases. Whether both forms are in the same series I can not determine. There are from four to five of the smaller to an inch.
| Measurements of Type of Leptophractus obsoletus Cope. | |
| mm. | |
| Depth of fragment of jaw | 75 |
| Length of smaller teeth | 19 |
| Length of longer tooth | 23 |
| Width of vertex at middle scuta | 176 |
| Width of paired median scuta | 56 |
| Width of single scute | 36 |
| Length of single scute | 48 |
"Some vertebræ were found at the same locality, but there is no evidence as to the species to which they may have pertained. They are short, concave on one end, and probably so on the other. The centrum of one is 12 mm. in diameter; neural spines injured." (Geol. Surv. Ohio, II, pt. II, pl. 39, fig. 3.)
"A third and larger specimen was found by Professor Newberry during the field season of 1874. It includes an oblique view of one side, and the top of the cranium from the posterior part of the orbits to the end of the muzzle, with the corresponding part of the alveolar region of the dentary bone, with teeth. The bones of the skull appear to have been rather light, and though the surface is irregular, the sculpture consists only of shallow impressions of varying size and intervals. The orbits are also badly defined, but appear to have been large, and separated by a narrow frontal bone. The premaxillary bone is preserved, and shows clearly the sutures that separate it from its fellow and from the maxillary. A large foramen—perhaps the nostril—separates it from the maxillary, so that it forms an irregular crescent. It supports two teeth, of which the anterior is the larger, but there were perhaps others in advance, as the alveolar border is imperfect towards the end of the muzzle. The anterior two teeth of the maxillary bone are followed by a strong groove which rises towards the sides of the muzzle. At first sight this gives the impression of the maxillo-premaxillary suture, and makes it appear that both the premaxillary bones are preserved, and that the foramen above described separates the premaxillary spines, instead of representing the nostril. The cutting edges of the teeth of these bones have, however, one direction, whence they represent one side of the cranium only; were both sides represented, the directions of the tooth axes would be reversed.
"The premaxillary and maxillary teeth exhibit a cutting edge on the outer posterior margin of the distal half; the base of the crown is subround in section. The line-like grooves are distinct but not numerous, their intervals measuring 75 mm. Beyond them the enamel is smooth. The second maxillary tooth is larger than the first, which is equal to the last premaxillary. The third and fourth maxillaries are equal to the second, but the fifth is larger and longer, exceeding all the others. The teeth of the dentary bone differ from those of the upper jaw in having the cutting edge of the crown on the anterior aspect, while the posterior border is obtuse. There is an obtuse cutting edge on the posterior margin of the anterior mandibular teeth.
"This description is derived from an adult animal, as the maxillary teeth in some instances are partially worn away by friction on their anterior and outer faces."
| Measurements. | |
| mm. | |
| Length of maxillary bone preserved | 146 |
| Length of same supporting five teeth | 73 |
| Length of first maxillary tooth | 15 |
| Diameter of same at base | 6 |
| Diameter of second at base | 8 |
| Length of basis of fifteen teeth of the dentary | 145 |