The carnivorous Australian marsupial known as the “marsupial lion” was Thylacoleo, which disappeared roughly 40,000–46,000 years ago. The best-known species was Thylacoleo carnifex.
Thylacoleo was an apex predator of Pleistocene Australia, despite belonging to a marsupial lineage whose living relatives include wombats and koalas. It was powerfully built and may have weighed roughly 100 to 160 kilograms, comparable to a large modern big cat. Its most distinctive weapons were blade-like premolars and large claws, adaptations suited to cutting flesh and gripping prey.
The name “marsupial lion” describes its ecological role and superficial resemblance to a lion; it was not a true cat. It is also easily confused with the thylacine, or Tasmanian tiger, which was a different, more lightly built marsupial. Fossils suggest Thylacoleo vanished during Australia’s broader Late Pleistocene megafaunal losses, around the period when humans had established themselves on the continent.