The Lower Permian amphibamid Doleserpeton (Temnospondyli: Dissorophoidea), the interrelationships of amphibamids, and the origin of modern amphibians

ABSTRACT The Lower Permian amphibamid Doleserpeton annectens (Temnospondyli) is of great importance to our understanding of the origin of modern amphibians. Here, we describe this taxon in detail. The pedicellate bicuspid dentition of Doleserpeton is more similar to that of modern amphibians than any other Palaeozoic form, including Gerobatrachus. The dermal bones of the skull are almost completely smooth, unlike other dissorophoids. The braincase and parts of the postcranial skeleton are more highly ossified than in other amphibamids, and Doleserpeton is unlikely to represent a juvenile stage. The ribs are relatively short and posteriorly curved, as in many modern amphibians, but unlike most lepospondyls. The palate shares numerous features with modern amphibians, including the configuration of the interpterygoid vacuities and the structure of the vomers. We propose that the closest sister taxon to Amphibamidae is Dissorophidae (armored dissorophoids) and that the trematopids are more basally situated th...