The oldest described vombatid, Rhizophascolonus crowcrofti, is known from late Oligocene/early Miocene deposits in South Australia. It was described based on a single isolated tooth originally interpreted to be P3. It is also the only described vombatid known to have had tooth roots, all others being hypselodont. This paper describes two additional isolated teeth referable to this taxon from the same deposit and presents a re-interpretation of the type specimen as an M4. Possible function of the extensive, but asymmetrically distributed, molar enamel is discussed. Analysis of the structure and probable function of all three teeth leads to the hypothesis that R. crowcrofti was rhizophagous.

(Parts of this abstract were presented at the London Evolutionary Research Network [LERN] 5th annual conference at the Natural History Museum in London on September 14, 2007.)