THE FIRST complete skeleton of the terrifying Marsupial lion reveals the huge predator was an adept hunter that got around with the help of a strong tail.

Weighing up to 100-kilos, the extinct Australian beasts were unlike any living animal, built to climb trees and cave walls and ambush helpless prey, a study of ancient bones shows.

The remains allowed scientists at Flinders University in Adelaide to reconstruct the animal's entire skeleton for the first time.

The marsupial lion lived in Australia around 45,000 years ago, at a time when giant animals like the woolly mammoth still ruled the Earth.

In recent years, marsupial lion fossils have been found in Komatsu Cave in Naracoorte and Flight Star Cave in the Nullarbor Plain.

New analyses of their structure showed the animals were built to climb trees and grasp prey.

This suggests the marsupial was "a scavenger, ambush predator of large prey", researchers wrote in the journal Plos One.

Its tail was stiff and heavily muscled, allowing it to be used along with the back legs as a "tripod" to brace the body while freeing up the front limbs for handling food or climbing.

While this would not have been good for chasing down prey, the experts say the creature would have been well-adapted for ambush hunting.

It bone structure suggests the animal was well-suited to climbing – either cave walls or forest trees.

Scientists said the marsupial lion's anatomy could be compared to that of the Tasmanian Devil, though the living animal is far smaller.

"The structure of its backbone, pectoral and pelvic girdles along with limb mechanics argue against a pursuit predator and point more towards a stealth or ambush predator and scavenger; a niche today occupied by S. harrisii," the researchers wrote.

"We suggest T. carnifex, as the apex marsupial carnivore, occupied a similar niche but scavenged/ hunted larger prey."