Scientists find 19 million year old marsupial lion at Riversleigh

Reconstruction of Wakaleo schouteni challenging a thylacinid over a kangaroo carcass at Riversleigh (illustration by Peter Schouten).
Reconstruction of Wakaleo schouteni challenging a thylacinid over a kangaroo carcass at Riversleigh (illustration by Peter Schouten).

Scientists have discovered a new species of marsupial lion extinct for 19 million years in the fossil-rich Riversleigh World Heritage Area of North West Queensland.

The findings, published in the Journal of Systematic Palaeontology, are based on fossilised remains of the animal’s skull, teeth, and humerus (upper arm bone) found by University of New South Wales scientists.

Named for palaeoartist Peter Schouten, Wakaleo schouteni was a predator that stalked Australia’s rainforests 18 to 26 million years ago. This meat-eating marsupial is estimated to have been about the size of a dog and weighed around 23 kilograms.

The new species is about a fifth of the weight of the largest and last surviving marsupial lion, Thylacoleo carnifex, weighing 130 kg, which went extinct 30,000 years ago. These lions had highly distinct large, blade-like, flesh-cutting premolars to tear up prey.

The discovery comes a year after the fossilised remains of a kitten-sized marsupial lion were found in the same site. The UNSW scientists named that miniature predator Microleo attenboroughi after broadcasting legend Sir David Attenborough.

Researchers now believe two species of marsupial lion were present 25 million years ago. The other, Wakaleo pitikantensis, was slightly smaller and was identified from teeth and limb bones discovered near Lake Pitikanta in South Australia in 1961.

Lead author UNSW palaeontologist Dr Anna Gillespie said the latest finding raises questions about the evolutionary relationships of marsupial lions.

“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.

They reveal the new species exhibits skull and dental features of Wakaleo but also shared similarities with P. pitikantensis including three upper premolars and four molars.  Smilarities of the teeth and humerus shared with W. schouteni indicate P. pitikantensis is a species of Wakaleo.

According to the authors, these dental similarities distinguish W. schouteni and W. pitikantensis from later species and suggest they are the most primitive members of the genus.