New species of giant fossil kangaroos from Australia and New Guinea

Palaeontologists have described 3 new species of extinct megafauna kangaroos which lived from about 5 million to 40,000 years ago.

The megafaunal macropodids in the genus Protemnodon would have looked something like a grey kangaroo but were generally squatter and more muscular.

One new species named as part of the study, Protemnodon viator, weighed up to 170 kg – about twice as much as the largest male red kangaroos today.

P. viator lived in central Australia and was a long-limbed kangaroo that could hop fairly quickly and efficiently. Its name, viator, is Latin for ‘traveller’ or ‘wayfarer’.

“Living kangaroos are already such remarkable animals, so it’s amazing to think what these peculiar giant kangaroos could have been getting up to,” says Dr Isaac Kerr of Flinders University, lead researcher of the new study in the journal Megataxa.

Photograph of the bones of a fossilised ancient kangaroo megafauna
An almost-complete skeleton of Protemnodon viator is shown, missing just a few bones of the hand, foot and tail. This specimen, SAMA P59552 from Lake Callabonna, is the holotype for the newly described species. This means that this specimen is the best representative of the species, as chosen by the researchers that described it. Credit: Isaac A. R. Kerr

While it was previously suggested that some or all Protemnodon were quadrupedal, according to Kerr: “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 Fossil Cave on the land of the Boandik people, near Mount Gambier in South Australia. The species name, mamkurra, was chosen by Boandik Elders and language experts in the Burrandies Aboriginal Corporation. It means ‘great kangaroo’ in the Bungandidj language of the Boandik people.

A photograph of a man in a lab, with fossilised specimens in the background. He is holding up two fossilised jaw bones, one much smaller than the other
Palaeontologist Dr Isaac Kerr displays the fossil jaw of the giant kangaroo Protemnodon viator and the far smaller jaw of the largest living kangaroo, the red kangaroo. Credit: Flinders Media Team

The third of the new species, Protemnodon dawsonae, was most likely a mid-speed hopper, something like a swamp wallaby. It was named in honour of the research work of Australian palaeontologist Dr Lyndall Dawson.

Protemnodon fossils are fairly common across Australia but, historically,have been found as individual bones without the rest of the animal. This has hampered palaeontologists’ study of the genus in the past, making it difficult to determine the number of species and how to tell them apart.

This changed with the discovery of multiple complete fossil kangaroo skeletons from Lake Callabonna in arid South Australia in 2013, 2018 and 2019. This allowed Kerr, then a PhD student, to begin to put together the puzzle. 

“It’s great to have some clarity on the identities of the species of Protemnodon,” says Gavin Prideaux, Director of Flinders Palaeontology and co-author of the new research.

“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.”

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