Around 18 million years ago, a feisty squirrel-sized marsupial roamed around the dense jungle of ancient Australia but has since gone extinct.

In a new study, scientists from the University of New South Wales describe how they identified this ancient marsupial lion for the first time. They named the new species in honor of prominent British naturalist Sir David Attenborough.

"Micro Lion"

Designated Microleo attenboroughi, the tiny marsupial is a member of the family Thylacoleonidae. Its name alludes to its size — micro means small in Greek — and status — leo means lion in Latin.

The last name of the creature — attenboroughi — recognizes Sir Attenborough's work in the field of natural history, particularly in uncovering paleontological treasures in the Riversleigh World Heritage Area in Queensland, Australia.

When it was alive, the M. attenboroughi weighed just about 1.3 pounds (0.58 kilograms), lived in trees and possessed molars that were strong enough to rip apart other tiny creatures, scientists say.

Anna Gillespie, one of the study researchers, says M. attenboroughi would have been the "feisty kitten" of the Thylacoleonidae family.

"It was not lion-size or even bob-cat-size," says Gillespie.

And like most marsupial carnivores, M. attenboroughi had long and dangerously sharp knife-like premolar that protruded from in front of its bottom molars.

Gillespie and colleagues identified this Australian micro lion from a teeth fossil and a partial skull. These 18-million-year-old remains were uncovered from the Neville's Garden Site at Riversleigh.

According to Gillespie, the micro lion shared the northern Miocene rain forests with two other larger species of marsupial lions, one dog-sized and the other cat-sized.

It was plausible that the animals competed with each other, but their differences in size meant that they had specialized on different size ranges of prey.

Marsupial Relatives

M. attenboroughi is the ninth and smallest marsupial lion ever identified at Riversleigh.

The first identified species were the Thylacoleo carnifex, which was the last of their kind to go extinct, researchers say. T. carnifex was identified in the late 1850s and fully described in 1999. It was about the size of a modern lion at about 5 feet long and 2 feet tall and could rip through its prey with its jaws. The ancient creature persisted through the Pleistocene until it was wiped out.

Furthermore, M. attenboroughi is called a "lion" for a different reason. It refers to the status of the ancient marsupials as hunters, like big cats. Indeed, researchers say marsupial lions are not the ancestors of modern lions in Africa, although ancient marsupial lions are related to koalas and other modern marsupials.

The findings of the new report are published in the journal Palaeontologia Electronica.