The three new species belong to the extinct kangaroo genus Protemnodon, which were common members of Cenozoic communities across Australia and New Guinea until their extinction in the Late Pleistocene.
An artist’s impression of the newly-described fossil species Protemnodon viator and its relative Protemnodon anak, compared at scale to the living red kangaroo and eastern gray kangaroo. Image credit: T. Klarenbeek, Flinders University.
Protemnodon kangaroos lived in Australia and New Guinea from around 5 million to 40,000 years ago.
The first species of Protemnodon were described in 1874 by British paleontologist Owen who followed the common approach of the time, to focus chiefly on fossil teeth. He saw slight differences between the teeth of his specimens, and described six species of Protemnodon.
Protemnodon would have looked something like a gray kangaroo, but were generally more squat and muscular.
While some species were around 50 kg, others were much larger than any living kangaroo.
However, one new species named as part of the study — Protemnodon viator — was much bigger, weighing up to 170 kg. This is about twice as much as the largest male red kangaroos.
Protemnodon viator was well-adapted to its arid central Australian habitat, living in similar areas to the red kangaroos of today.
The species was a long-limbed kangaroo that could hop fairly quickly and efficiently.
The two other new species are Protemnodon mamkurra and Protemnodon dawsonae.
“It previously was suggested that some or all Protemnodon were quadrupedal,” said Dr. Isaac Kerr, a paleontologist at Flinders University.
“However, our study suggests that this is true of only three or four species of Protemnodon, which may have moved something like a quokka or potoroo — that is bounding on four legs at times, and hopping on two legs at others.”
“The newly-described Protemnodon mamkurra is likely one of these. A large but thick-boned and robust kangaroo, it was probably fairly slow-moving and inefficient. It may have hopped only rarely, perhaps just when startled.”
“The best fossils of this species come from Green Waterhole Cave in southeastern South Australia, on the land of the Boandik people.”
“It’s unusual to have a single genus of kangaroo live in such varied environments. For example, the different species of Protemnodon are now known to have inhabited a broad range of habitats, from arid central Australia into the high-rainfall, forested mountains of Tasmania and New Guinea.”
Protemnodon dawsonae is known from fewer fossils than the other two species, and is more of a mystery. It was most likely a mid-speed hopper, something like a swamp wallaby.
“By about 40,000 years ago, all Protemnodon were extinct on mainland Australia, maybe lingering a while longer in New Guinea and Tasmania,” the authors said.
“This extinction occurred despite their differences in size, adaptations, habitat and geographic range.”
“For reasons not yet clear the same did not happen to many similar and closely related animals, such as wallaroos and gray kangaroos. This question may soon be answered by further research aided in some part by this study.”
“It’s great to have some clarity on the identities of the species of Protemnodon,” said Flinders University’s Professor Gavin Prideaux.
“The fossils of this genus are widespread and they’re found regularly, but more often than not you have no way of being certain which species you’re looking at.”
“This study may help researchers feel more confident when working with Protemnodon.”
The discovery is reported in a paper published today in the journal Megataxa.
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Isaac A.R. Kerr et al. 2024. Systematics and palaeobiology of kangaroos of the Late Cenozoic genus Protemnodon (Marsupialia, Macropodidae). Megataxa 11 (1); doi: 10.11646/megataxa.11.1.1
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