AUSTRALIAN researchers have discovered a new species of extinct marsupial lion that once roamed the continent.

The animal, named Wakaleo schouteni, was a predator about the size of a border collie dog. It stalked Australia’s abundant rainforests some 18 to 26 million years ago.

Fossils of the unique species were found in remote northwestern Queensland and details of the discovery have been published today in the Journal Of Systematic Palaeontology.

Lead author Dr Anna Gillespie, a palaeontologist from the University of New South Wales (UNSW) in Sydney, said the findings mean researchers have had to change how they classify certain members of the marsupial genus.

A marsupial lion is “a family of extinct marsupials only found in Australia, their fossil history spans from about 24 million years ago up until about 30,000 years ago,” she told news.com.au. “They died out with the rest of the megafauna.”

The new species is about a fifth of the weight of the largest, most famous and last surviving marsupial lion, the Thylacoleo carnifex, which weighed about 130kg, researchers said.

“Complete skeletons of that animal have been found in caves in the Nullarbor and in South Australia,” Dr Gillespie said.

Members of this family, the Thylacoleonidae, had highly distinct large, bladelike, flesh-cutting premolars that they used to tear up prey.

With this new find, the researchers believe that two different species of marsupial lion were present in the late Oligocene period, at least 25 million years ago.

The other, originally named Priscileo pitikantensis, was slightly smaller and was identified from teeth and limb bones discovered near Lake Pitikanta in South Australia in 1961.

But given the dental similarity to the newly discovered marsupial lion, the P. pitikantensis has been renamed Wakaleo pitikantensis.

This latest discovery revealed that the new species exhibits many skull and dental features of the genus Wakaleo but it also shared a number of similarities with the previously discovered P. pitikantensis — particularly the presence of three upper premolars and four molars, a feature previously used to diagnose and classify fossil remains to the Priscileo family.

“Suddenly we had to go, ‘Oh no, we can’t use this feature to characterise this genus,’” Dr Gillespie said. “It showed us that the earlier forms of this genus had much more primitive features.”