A new genus of kangaroo (Marsupialia, Macropodidae) from the late Pleistocene of Papua New Guinea

The extinct macropodine kangaroo, Protemnodon nombe, was first described in 1983 on the basis of two partial dentaries from a late Pleistocene deposit in Nombe Rockshelter, Papua New Guinea. As part of a review of Protemnodon, we noted that P. nombe differed from other members of the genus in several ways that pointed to a position outside of that genus and indeed all other known macropodine genera. The taxon possesses a unique combination of attributes of the dentary and lower dentition, including lower molars with a slight postmetacristid, a small postprotocristid and a gently S-shaped protolophid crest. The proportions of masticatory muscle insertion areas, including a broad masseteric canal for the deep masseter, resemble those of sthenurines, suggesting adaptation to tougher browsed vegetation than other New Guinean macropodines. A parsimony analysis suggests a divergence near the base of the Macropodinae, potentially in the early late Miocene.