Fauna of the Vale and Choza : a new Trematopsid amphibian from the Vale formation

Abstract

INTRODUCTION The family Trematopsidae is represented in the early Permian of Texas by Acheloma in the Wichita group and Trematops in the Arroyo Formation of the Clear Fork group (see Olson, 1941). Until 1954 no members of this family had been discovered in post-Arroyo beds, although the persistence of the general habitat in which the earlier genera lived suggested that some members might well have survived the Arroyo-Vale transition. A recent discovery of a reasonably well-preserved skull and skeleton of a trematopsid in the lower part of the Vale Formation shows this, in fact, to have been the case, and adds this family to those previously recognized in the post-Arroyo Clear Fork deposits: CLASS AMPHIBIA Subclass Apsidospondyli Superorder Labyrinthodontia Order Rhachitomi Family Trematopsidae Trematopsis gen. nov. Diagnosis.—General characters of skull and post-cranium similar to those of Trematops and Acheloma. Proportional differences as shown in Tables 1 and 2. In specimens of comparable size, Trematopsis differs from Trematops and Acheloma as follows: snout shorter, orbits much larger, distal width of humerus and proximal and distal widths of femur less in proportion to length. Femur longer in proportion to skull length.