On the uncertain generic status and phylogenetic relationships of the large extinct vombatid species Phascolomys medius Owen, 1872 (Marsupialia: Vombatidae).

Abstract

A vombatid skull from Pleistocene deposits of Wellington Caves, New South Wales, is shown to be referable to Phascolomys medius Owen, 1872. It reveals characters of the palate that refute previously suggested allocation of this species to Lasiorhinus Gray, 1863. Cladistic analysis has yielded two hypotheses, both indicating a closer relationship of P. medius to either Phascolonus gigas (Owen, 1858) or to Ramsayia magna (Owen, 1872) , than to species of Lasiorhinus. Both hypotheses require many assumptions of parallelism and several reversals. The most parsimonious hypothesis indicates that Phascolomys medius is the sister group of Phascolonus gigas, but these species are not congeneric.