A trematopsid skull from the Lower Permian, and analysis of some characters of the dissorophoid (Amphibia, Labyrinthodontia) otic notch / John R. Bolt.

Abstract

The partial skull (UR 2400) described in this paper came from the Lower Permian Fort Sill locality, Comanche County, Oklahoma. This locality has been described elsewhere (see Gregory et ah, 1956; Olson, 1967). Olson's faunal list contains eight genera, of which all but one (Xenacanthus) are small tetrapods. This list can be expanded to 11 by the addition of Basicranodon (Vaughn, 1958), Phlegethontia (McGinnis, 1967), and Doleserpeton (Bolt, 1969). As Olson notes, there are certainly a number of undescribed forms in the fauna, but the usually disarticulated condition of materials and dispersal of collections hampers study. With the exception of Doleserpeton, UR 2400 is the first example of even a partial labyrinthodont amphibian skull described from Fort Sill. The specimen is thus important in providing a guide to association of well-preserved but disarticulated labyrinthodont dermal bones from Fort Sill. Excellent preservation of this skull fragment makes it useful in understanding the morphology of other dissorophoid labyrinthodonts, which are mostly known from less well-preserved red-beds specimens. (The superfamily Dissorophoidea was originally composed of Dissorophidae, Doleserpetontidae, and Trematopsidae (Bolt, 1969). Boy (1972) has added the Micromelanerpetontidae and Branchiosauridae, neither of which will be discussed here due to unavailability of material). Finally, UR 2400 is of interest as a possibly new species of trematopsid.