THE GEOLOGICALLY YOUNGEST ALBANERPETONTID AMPHIBIAN, FROM THE LOWER PLIOCENE OF HUNGARY

Abstract:  The Albanerpetontidae are salamander-like, Middle Jurassic to Neogene lissamphibians from Laurasia and North Africa. Extensive series of albanerpetontid bones recently identified in collections from the Csarnóta 2 locality, south-central Hungary, extend the temporal range of the clade forward about seven million years from the middle Miocene to the early Pliocene. The Hungarian material is diagnostic for the Euramerican type genus Albanerpeton and pertains to a new species, A. pannonicus sp. nov., which differs from the seven previously reported congeners (Early Cretaceous–Miocene) in a distinctive combination of primitive and derived character states of the jaws and frontals, including a unique ventromedian keel on the azygous frontals. Some of the Hungarian specimens are articulated sets of skull bones, including ones containing the first three-dimensional examples of a nasal and jugals known for albanerpetontids, that help clarify some details of cranial osteology in these amphibians. Cladistic analysis nests A. pannonicus within the robust-snouted clade, as the sister taxon to an unnamed late Palaeocene species from Canada and A. inexpectatum from early–middle Miocene deposits in France, Austria and Germany. This phylogeny and recent reports of diagnostic Albanerpeton material from the Campanian of France and Maastrichtian of Romania suggest the evolutionary history of Albanerpeton was more complex than previously hypothesized, with Europe having played a larger role. The 25 fossiliferous layers at Csarnóta 2 record a shift from forest to grassland palaeoenvironments. Fossils of A. pannonicus are present in all layers, implying that this species was not adversely affected by the change in palaeoenvironments.