New Species of Extinct Marsupial Lion Deepens Their Fierce Family Tree

The dog-sized animal adds more diversity to the history of Australia’s largest predator

Marsupial Lion
Wakaleo schouteni Peter Schouten in the Journal of Systematic Palaeontology

Most modern marsupials are pretty cute and cuddly—koalas, kangaroos, wallabies, wombats, sugar gliders and even some types of possums are pretty sweet. But the ancient marsupial lions are far from adorable furballs. And as Elaina Zachos reports for National Geographic, the newest member of the group adds even more diversity to their already fierce ranks.

Researchers analyzed the skull, teeth, and an upper arm bone of Wakaleo schouteni, concluding the creature lived around 18 to 26 million years ago. Though some of the marsupial lions were as small as squirrels, surprisingly the newest species likely grew to be dog sized.

"The identification of these new species has brought to light a level of marsupial lion diversity that was quite unexpected and suggest even deeper origins for the family," Gillespie says in a press release.

The remains were actually discovered in the 1980s by a volunteer in the Riversleigh World Heritage Area in Queensland, Australia. But it took over two decades of work to finally recognize the bones as a new species, reports Calla Wahlquist reports for The Guardian.

Anna Gillespie, paleontologist at the University of New South Wales, began studying the creature's remains in the 1990s while working on her PhD. And after careful careful study and comparison to other fragments, she finally concluded that it was a new species. She and her colleagues detail the find in a study published this week in the Journal of Systematic Palaeontology.

What is a marsupial lion? As Gillespie writes at The Conversation, the creature is not really a lion, but a thylacoleonidae—a group of marsupials that existed in Australia between 24 million and 30,000 years ago. 

Paleontologists originally called them lions because of their status as top predators, sporting a pair of blade-like teeth. (These were particular impressive in Thylacoleo carnifex, the last of the marsupial lions and Australia’s largest-ever predator.)

In the beginning, they were thought to be tree-dwelling omnivores, but over time they got heavier and took on larger prey, growing to the size of dogs for the later species. But the newest branch to the family tree overturns this idea. Dating suggests that the new species existed during the same time as a squirrel-sized lion, Microleo attenboroughi, identified last year, which means that the marsupial lion family tree is much more complicated than researchers once thought.

"They would have been around at the same time. They're actually known from the same particular fossil site," Christine Janis, a paleontologist not involved in the research tells Zachos. "They would have been very different in size and so would have been different kinds of predators."

Scratch marks found in a cave last year showed even the larger species to evolve likely retained the climbing skill of the smaller ones, and researchers believe that they didn’t chase down their prey but dropped onto them from the trees. As Gillespie tells Wahlquist, the arms of Wakaleo schouteni are not complete enough to directly deduce its habitat, but fossils discovered near it suggest that it too spent a lot of time in the trees, stalking its prey from tree to tree. 

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