National Geographic Today
A team of amateur spelunkers has discovered caves filled with very well preserved fossils of giant flat-faced kangaroos, marsupial lions, wombats, Tasmanian tigers, and other megafauna that lived in Australia during the Pleistocene era, between 1.75 million and 10,000 years ago.
Paleontologists who have been investigating the cave, which is in a remote region of Australia's Nullarbor Plains in the state of Western Australia, have called it "the find of the century."
"A find like this comes along once in a lifetime, if you are lucky," said Gavin Prideaux, curator of the Naracoorte Caves collection at Flinders University in Adelaide and an expert on the Pleistocene cave fossils. "It was actually a pretty strange situation because with the first one, two, three specimens you feel you are over the moon with excitement, but everywhere we turned we found more stuff."
One of the most exciting discoveries is the first complete skeleton of a flesh-eating marsupial "lion," Thylacoleo carnifex, said John Long, curator of vertebrate paleontology at the Western Australian Museum in Perth, who led the three-week expedition, dubbed Operation Leo, at the site. To date eight skeletons of Thylacoleo have been found in these caves.
"After finding the sixth, seventh, eighth specimen, it's overwhelming and exhausting to maintain excitement," added Prideaux. "It becomes, 'Oh wow, here is another perfectly preserved and complete skeleton of a Thylacoleo.'"
Thylacoleo is not a lion; it is more closely related to koalas and kangaroos. It is the largest carnivorous mammal ever to have lived in Australia and the largest known marsupial carnivore in the world.
At about two meters long, it was about the same size as a leopard, with massive paws and forearms, huge retractable claws, and enormous "opposable thumb-like" appendages that were probably used for tree climbing. Unlike the large cats that have two enlarged canines, marsupial lions had enlarged incisors that were used to stab prey.
Also among the caves' bounty are skeletons of up to 10 different species of extinct kangaroos; about 75 percent of the skeletons are complete, including three from giant kangaroos that were as tall as three meters (10 feet). There are also remains from the flat-faced giant kangaroo Procoptodon goliah, the largest of all kangaroo species.