Morphology and systematics of the Pennsylvanian amphibian Platyrhinops lyelli (Amphibia: Temnospondyli)

The morphology of the amphibamid temnospondyl amphibian Platyrhinops lyelli from the Middle Pennsylvanian of Linton, Ohio is reassessed from previously described and undescribed specimens. Newly reported or newly significant features include the presence of bicuspid marginal teeth, anteriorly widened frontals, elongate choanae, a broad rhomboidal sphenethmoid and a pair of flattened blade-like ceratohyals. One specimen shows an unusual distribution of tooth sizes along the premaxillaries. No derived characters can be found to justify reference of the species lyelli to the genus Amphibamus as represented by its type species A. grandiceps, but Platyrhinops does belong to the ‘Amphibamus branch’ of the Amphibamidae.