Restudy of Mycterosaurus longiceps (Reptilia, Pelycosauria) from the Lower Permian of Texas

Abstract

Study Of Mycterosaurus longiceps Williston from the Lower Permian (Leonardian) Clyde Formation of north-central Texas strongly suggests that this small pelycosaur is a primitive member of the family Varanopseidae. M. longicepx has been formerly in- cluded in the family Nitosauridae as a primitive edaphosaur and considered close to the ancestry of the caseids. This assignment was based almost exclusively on postcranial features recorded from a small portion of skeleton probably belonging to a temnospon- dylous amphibian, possibly a dissorophid, that was confused with a referred specimen. The possession by M. [angicepx of several specialized features also suggests that it may represent an early divergent lineage from the central stock that comprises the other Permian varanopseids.