Australia's 100kg marsupial lions could have eaten humans, say scientists By Peter Spinks A fossil reconstruction, above, and an artist's impression create a terrifying picture of Thylacoleo carnifex. 
Artwork: Peter Schouten, courtesy University of NSW; Photo: Gavin Prideaux, Flinders University Marsupial lions were Australia's top mammalian predators, with meat- slicing teeth, razor-sharp claws and the ability to climb in caves where they reared their young communally, scientists have found.
The Flinders University research, published in Nature's Scientific Reports, reveals the unique meat- eating mammals left thousands of claw marks in a limestone cave in south-western Australia.
The claw marks, along with a rich deposit of fossilised bones, were unearthed in the aptly named Tight Entrance Cave near Margaret River.
Closely related to plant eaters such as possums and wombats, the lions, known scientifically as Thylacoleo carnifex, weighed up to 100 kilograms and became extinct about 40,000 years ago.
"The stocky-yet-agile predators presented a formidable threat to herbivores such as giant, short-faced kangaroos and humans," said lead researcher Associate Professor Gavin Prideaux.
"Marsupial lions, often portrayed in Aboriginal rock art, were apparently adapted to apprehending and consuming large prey, so it is feasible they hunted co-operatively", he explained.
Such a strategy probably allowed them to prey on the largest marsupial of its time, the rhinoceros- sized Diprotodon optatum, bones of which have been found with marsupial-lion bite marks.
"The largest scratch marks in the caves could only have been made by adult lions," Associate Professor Prideaux said. Many of the smaller marks were made by juveniles: they have the same form as those of adults but do not match marks of other known cave dwellers.
"Marsupial lions, like all marsupials, would have given birth to extremely underdeveloped young that could not be left alone until becoming at least partially weaned," he said.
Caves provided a safe, climate- controlled environment for raising young defensible against other carnivores such as thylacines, the Tasmanian doglike marsupials with stripes across their rumps.
Many of the Tight Entrance Cave claw marks were on very steep surfaces up to three metres from the cave floor.
"This was probably the quickest route to the exit hole in the cave roof," Associate Professor Prideaux said.
"They could have chosen longer routes to the exit with gentler slopes, but the distribution of claw marks shows that, habitually, they did not," said co-researcher Sam Arman.
"Clearly they were excellent climbers and would easily have been able to climb trees."