Researchers from Flinders University say they have identified three new species of extinct kangaroo, helping solve a nearly 150-year-long scientific mystery.

The university said the kangaroos were all part of the extinct genus Protemnodon but the palaeontologists behind the study said they varied widely in size.

The largest weighed up to 160 kilograms — double the size of the current-day heavyweight red kangaroo.

The breakthrough took lead researcher Isaac Kerr more than five years and involved trips across the world to examine fossils in British and American museums, as well as in New Guinea.

“We visited 14 collections in four museums around the world,” Dr Kerr said. “It’s been a long time coming.”

Mr Kerr travelled to Port Moresby to take a 3D scan of the jaw bones.(Supplied: Flinders University)

Dr Kerr took detailed photos of the kangaroo fossils and conducted 3D scans at the museums he visited, taking the data home on a hard drive to examine the minute details.

He then compared these against fossils of giant marsupials and kangaroos found in Lake Callabonna, in northern South Australia.

By comparing all the known Protemnodon species, Dr Kerr was able to find and describe three new species: the viator, the mamakurra and the dawsonae.

What were these extinct roos like?

The three species are quite distinct from one another, but the viator is thought to be the largest.

“It was probably a bit like a red kangaroo, but a bit more thick-boned and muscular,” said Dr Kerr.

“It probably lived around the sort of the big lakes and creeks that were in Central Australia at the time.”

An artist’s impression of south-eastern South Australia during the Pleistocene (about 500 thousand years ago) showing many of the plants and animals that lived there alongside Protemnodon.(Supplied: Flinders University/Peter Schouten)

According to Dr Kerr, the mamakurra most likely had a similar diet to the viator, but were smaller.

The species lived along the south coast of Australia, from Western Australia and South Australia, in the mountains of Tasmania and around the east coast of New South Wales.

It also had a different bone structure and was more prone to moving around on its hands and feet, rather than hop.

Less is known about the dawsonae, but it may have been the ancestor to the viator and mamakurra, Dr Kerr said.

“It’s seeming sort of somewhere in the middle of those two,” he said.

“Maybe something like a swamp wallaby or redneck wallaby from today.”

Protemnodon species vary in size and appearance, but some are bigger than modern day kangaroos. (Supplied: Flinders University. )

The newly discovered Protemnodon species are believed to have died out about 40,000 years ago, but palaeontologists aren’t exactly sure why.

Unlike some megafauna, there is no evidence to suggest the kangaroos fell victim to a huge climate event — or were hunted.

“They definitely died out once humans arrived … but there’s absolutely no evidence to show that Aboriginal people hunted Protemnodon,” Dr Kerr said.

Dr Kerr says the dawsonae was likely similar to today’s swamp wallaby.(ABC News: Ellie Grounds)

The first species of Protemnodon was identified by British naturalist Richard Owen in 1874, and successive studies have disproved some of the early descriptions.

They were previously thought to have all been quadrupeds, travelling on all fours as opposed to hopping like the kangaroos of today.

However, Dr Kerr found this was only the case for only three or four Protemnodon species, which “may have moved like a quokka or potoroo”.

Could technology bring them back to life?

The research offers a much larger database of Protemnodon species than previously available, which could give scientists more information in identifying fossils.

“It’s great to have some clarity on the identities of the species of Protemnodon,” said Flinders University director of palaeontology Gavin Prideaux.

“This study may help researchers feel more confident when working with Protemnodon,” he said. 

Palaeontologists uncovered Protemnodon fossils in northern South Australia, which helped identify the three new species.(Supplied: Flinders University )

Some scientists are passionate about bringing back extinct animals like the woolly mammoth and Tasmanian tiger. 

Dr Kerr said although it was unlikely to happen, it wouldn’t be impossible to bring some of the extinct kangaroos back to life.

“The Australian Centre for Ancient DNA at Adelaide University have collected [Protemnodon‘s] whole genome,” he said.

“I’m not sure anyone’s prioritising kangaroos in the de-extinction debate.

“Were people to start throwing that kind of technology at your less charismatic animals, I’m sure Protemnodon would be in line.”

Posted , updated