Australian researchers have discovered a new species of extinct marsupial lion that stalked the continent’s lush rainforests between 26 and 18 million years ago.
The study, published in the Journal of Systematic Palaeontology, identifies the new species from 19-million-year-old fossilised remains discovered at Riversleigh World Heritage Site in Queensland and comprises an almost complete skull, teeth, and upper arm bones.
“It is very rare to get a complete skull of a marsupial lion that is this old, so this specimen is a real treasure,” says palaeontologist Anna Gillespie from the University of New South Wales in Sydney, lead author of the paper.
Dubbed Wakaleo schouteni, the dog-sized predator was armed with the ferocious blade-like teeth characteristic of marsupial lions, perfect for slicing up the flesh of its prey: lizards, birds, frogs and small possums.
By carrying out a spot of palaeontological dentistry, the researchers also discerned that the species likely enjoyed small servings of vegetables – deduced from the broad basins of its molars, which suggest it moved its jaws to make small cutting and grinding motions.
Marsupial lions are the largest meat-eating mammals ever to have existed in Australia, but are unrelated to modern-day predators on the savannas of Africa.
W. schouteni, the new species, lived between 26 and 18 million years ago in the late Oligocene and the early Miocene and had a number of relatives.
Its best-studied cousin is Thylacoleo carnifex. Five times bigger than the border collie-sized W. schouteni, it was a powerful, highly specialised carnivore that roamed the continent until 40,000 years ago. There was also the slightly smaller Wakaleo pitikantensis, and the runt of the family, the kitten-sized Microleo attenboroughi, another marsupial lion discovered at the Riversleigh World Heritage Site last year.
One of the world’s most important and abundant fossils deposits, the remote site has also delivered fossils of Tasmanian Tigers, a carnivorous kangaroo, a flightless bird resembling a cross between an emu and a cassowary, a goanna-like crocodile and tree-dwelling marsupial cats. Most of the remains are from a period between 25 and 15 million years ago, giving researchers a window into the evolutionary timeline of many species.
The discovery of W. schouteni raises new questions about family ties on an evolutionary scale, says Gillespie. “The identification of these new species has brought to light a level of marsupial lion diversity that was quite unexpected and suggests even deeper origins for the family.”
But the picture is far from complete. While the lion left us a skull and arm bones, there are a lot of missing parts for Gillespie and her team to fill in: “What were its limbs, hands and feet like? Did it have a long or a short tail? We only have a few bones of the rest of the skeleton so it’s going to take some time to answer these questions.”