The findings are based on the discovery of fossilised remains of an animal's skull, teeth and upper arm bone found in the Riversleigh World Heritage Area of remote north-western Queensland. The predatory creature, named Wakaleo schouteni, is a relative of modern marsupials - mammals like kangaroos and koalas that keep their young in pouches, reported The Independent.
The new discovery, dubbed Wakaleo schouteni, was a meat-eating animal that weighed approximately 23 kilograms (50 pounds), and hunted in the Australian rainforests 18-26 million years ago.
It is also closely related to the last surviving species of marsupial lion, Thylacoleo carnifex, which had enormous dagger-like fangs and the strongest bite of any known mammal species. Members of this family, the Thylacoleonidae, had highly distinct large, blade-like, flesh-cutting premolars that they used to tear up prey. While at 130 kg the larger marsupial lions could have been a real threat to our ancestors, this new species is around the size of a dog, weighing around 23 kg.
The University of New South Wales scientists who made the discovery named the lion Wakaleo schouteni in honour of paleoartist Peter Schouten.
A smaller marsupial lion was found at the same site in Queensland past year.
Lead author Dr Anna Gillespie, a palaeontologist at UNSW in Sydney, said the latest finding raises new questions about the evolutionary relationships of marsupial lions. The UNSW scientists named that miniature predator Microleo attenboroughi after BBC's animal documentary broadcasting legend Sir David Attenborough.
Following the latest find, the researchers believe that two different species of marsupial lion were present in the late Oligocene at least 25 million years ago.
The Wakaleo schouteni didn't have almost the same toothy "smile", based on fossilized remains of its skull, teeth and an upper arm bone.
It was found at the internationally-renowned Riversleigh World Heritage Area in the remote north-western Queensland state, where the remains of a bevvy of unusual new small to medium-sized creatures have been discovered.
The researchers said the dental similarities distinguish W. schouteni and W. pitikantensis from later species of the genus, all of which show premolar and molar reduction, and suggest that they are the most primitive members of the genus.
"The identification of these new species have brought to light a level of marsupial lion diversity that was quite unexpected and suggest even deeper origins for the family", Dr Gillespie said.