The Significance of the Postcranial Anatomy of the Late Paleozoic

The Significance of the Postcranial Anatomy of the Late Paleozoic Diadectomorph family Limnoscelidae (Tetrapoda, Amniota?) Natalia K. Wideman*1,2 1 California State University San Bernardino, San Bernardino, CA 94222, U.S.A., 2 Museum of Paleontology, Claremont, CA 91711, U.S.A. The postcranial anatomy of the Late Paleozoic Diadectomorph family Limnoscelidae is significant because the Diadectomorpha are generally considered to be the sister group of the crown group Amniota. In fact, Diadectomorpha’s relationship with Amniota is so close that the former have frequently been suggested as amniotes in both crown-based and node-based studies. The Limnoscelidae are probably the most basal family within Diadectomorpha and therefore provide an important frame of reference for studies of diadectomorph and basal amniote interrelationships. For example, the postcranial structure of limnoscelids provides important data bearing on the locomotor capabilities of basal Diadectomorpha. At least six genera have been reported as belonging to Limnoscelidae, though all but Limnoscelis are represented by fragmentary materials restricted to the postcranium. The anatomy and phylogenetic validity of the various of limnoscelid genera were reviewed. The survey of the postcranial anatomy of limnoscelids suggests that, with the exception of Limnoscelis itself, some, if not most, of the genera assigned to the family Limnoscelidae are not valid taxa. The genus with the most confidently valid morphological basis remains Limnoscelis. Thus, Limnoscelis provides a significant structural model for the postcranium of taxa near the amphibian to amniote transition.