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