Lissamphibian origins: possible protolissamphibian from the lower permian of oklahoma.

A new genus and family of rhachitomous labyrinthodont amphibian, related to the Upper Paleozoic Dissorophidae and Trematopsidae, may be ancestral to some or all of the modern Amphibia. Doleserpeton occurs in Lower Permian fissure fill deposits in southwestern Oklahoma. It is unique among nonlissamphibian tetrapods in that it possesses pedicellate, bicuspid teeth together with nearly monospondylous vertebrae in which the main central element is a pleurocentrum. Doleserpeton may have been utilizing the food resources of the upland, terrestrial environment in a novel fashion for rhachitomes.