A reassessment of the temnospondyl amphibian Perryella olsoni from the Lower Permian of Oklahoma

Additional mechanical preparation of the type material of the temnospondylamphibian Perryella olsoni (Lower Permian, Wellington Formation, Oklahoma) highlights newcranial and postcranial features and provides additional data on previously known structures.Important new information is available for the quadrate, palatal bones and their associateddentition, parasphenoid, and appendicular skeleton. The revised diagnosis and redescription ofPerryella provide the basis for a re-evaluation of its systematic affinities. A cladistic analysis of(mostly) Carboniferous and Permian temnospondyls, together with several Devonian andCarboniferous stem tetrapod outgroups, supports a single origin for temnospondyls. The sequenceof branching events within temnospondyls consists of: (1) a paraphyletic Edopoidea; (2) a clade ofZatracheidae, Eryopidae, and basal Archegosauriformes; (3) a monophyletic Dvinosauria; and (4) amonophyletic Dissorophoidea. Perryella is nested within Dvinosauria in an intermediate positionbetween Trimerorhachidae and Dvinosauroidea.