MONOPHYLY AND INTRA-GENERIC RELATIONSHIPS OF ALBANERPETON (LISSAMPHIBIA; ALBANERPETONTIDAE)

The first phylogenetic analysis of the Euramerican Early Cretaceous–Miocene genus Albanerpeton is presented based on 16 characters of the jaws, frontals, and inferred body size scored for the seven recognized species in the genus and three other albanerpetontid taxa. Monophyly of Albanerpeton is corroborated and nested sets of synapomorphies yield the following hypothesized relationships: A. arthridion ((A. cifellii + A. galaktion + A. gracilis) (A. nexuosus (unnamed late Paleocene species + A. inexpectatum))). Osteological modifications identified in Albanerpeton initially involve the frontals, then shift largely to the jaws. Many of these changes are interpreted to be associated with broadening the head and strengthening the snout and jaws, presumably for feeding and burrowing. The first half or more (latest Aptian/earliest Albian to late Paleocene) of the known record for Albanerpeton and six of the seven species are restricted to the North American Western Interior. These occurrences and the phylogenetic framework proposed here suggest that the evolutionary history of Albanerpeton was centered in the Western Interior of North America.