Scientists have described a new genus of robust, late Pleistocene prehistoric kangaroo from fossils found in Papua New Guinea. Analysis suggests that it was not closely related to kangaroos found today in Australia.

Researchers from Flinders University examined two partial dentaries (lower jaw bones) that had been previously assigned to the Protemnodon genus and named P. nombe. They identified unique characteristics in the teeth and the shape of the bones that led them to conclude that the fossils were sufficiently different from other Protemnodon material to be assigned their own genus. The ancient kangaroo has been named Nombe nombe honouring the Nombe Rockshelter where the fossils were discovered.

Nombe nombe life reconstruction.
A life reconstruction of the prehistoric kangaroo Nombe nombe. Standing around 1.5 metres tall and weighing up to 60 kilograms, the thick dentary and strong teeth indicate Nombe evolved to eat tough leaves in the dense jungle landscape. Picture credit: Peter Schouten.

A New Guinea/Australia Land Bridge

During the Miocene Epoch, around 5-8 million years ago, lower global sea levels permitted a land bridge between Australia and Papua New Guinea to form. This led to a faunal interchange between the two regions. An ancient form of Australian kangaroo migrated northwards and entered the territory now known as Papua New Guinea. When sea levels rose and the Torres Strait was formed, these ancient kangaroos were able to evolve in isolation away from their Australian ancestors.

Nombe nombe dentaries.
Nombe nombe lower jaw bones. Holotype and referred specimen of Nombe nombe: holotype (PNG/82/40/23) partial right dentary in (a) buccal/lateral view, (b) lingual/medial view and (c) lower dentition in occlusal/dorsal view; (d) referred specimen (PM/82/40/19) partial left dentary in buccal/lateral view. Picture credit: Kerr and Prideaux.

Co-author of the scientific paper published in the Transactions of the Royal Society of South Australia, PhD student Isaac Kerr commented:

“The New Guinean fauna is fascinating, but very few Australians have much of an idea of what’s actually there.”

Co-author of the paper, Professor Gavin Prideaux (Flinders University), explained that excavations at the Nombe Rockshelter and elsewhere in central Papua New Guinea are providing palaeontologists with evidence of a unique ecosystem on the island, a biota dominated by prehistoric marsupials that were adapted to their mountainous, tropical environment. Flinders University hopes to be able to undertake more extensive fieldwork over the next three years and they are confident that these excavations will unearth new species.

Prehistoric Papua New Guinea
Life in the late Pleistocene on Papua New Guinea. The megafauna was dominated by extinct species of kangaroo and giant four-legged marsupials called diprotodontids, which in turn were hunted by Thylacines. Picture credit: Peter Schouten.

Everything Dinosaur acknowledges the assistance of a media release from Flinders University in the compilation of this article.

The scientific paper: “A new genus of fossil kangaroo from late Pleistocene New Guinea” by Isaac A. R. Kerr and Gavin J. Prideaux published in the Transactions of the Royal Society of South Australia.

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