An Australian folklore legend often used to intimidate tourists has been found by researchers to have existed in parts of eastern Australia about 15 million years ago.
International campers have for decades been led to believe the so-called drop bear, a koala-like carnivorous bear living in the treetops, would drop onto the heads of people walking beneath them.
Researchers from the University of New South Wales (UNSW) have found while drop bears don't currently occupy treetops, they did inhabit the canopy of lowland Australian rainforests in the Middle Miocene Epoch.
The marsupials, known as Nimbadon, weighed about 70 kilograms and were similar to wombats.
A study examined the makeup of Nimbadon's bones found in the Riversleigh World Heritage Area in north-west Queensland during the 1990s, with the results published in the Journal of Paleontology.
UNSW Pangea Research Centre Professor Mike Archer said the arboreal mammals could be compared to a "koala on steroids many times over".
"We originally thought they were kind of like marsupial sheep running around on the forest floor," he said.
"Their skeletons tell us they had to be up in the trees, virtually hanging upside down by gigantic koala-like claws, powerful forelimbs, rotating forelimbs that enable them to climb."
Professor Archer said the animals occasionally lost their footing and fell out of trees, sometimes dropping into caves that were formed in the forest floor.
"That's where we found them as fossils, articulated skeletons in these cave deposits," he said.
Tree-climbing crocodiles
The "drop bears" typically lived in rainforests between southern Queensland and NSW along with other animals such as flesh-eating kangaroos, tree-climbing crocodiles, lions, and giant-toothed platypuses.
"So if you didn't have to worry about being squashed by a Nimbadon, one of those weird drop bears, you were likely to be torn apart by a drop croc," Professor Archer said.
Professor Archer said the species became extinct due to climate change, with the temperature rising by about 2 degrees Celsius.
He said the rise in temperature caused about 50 per cent of animals in forests to disappear, with biodiversity only beginning to recover when temperatures dropped again hundreds of thousands of years later.
"So the message for us is if we let global temperatures rise the way they seem to be doing now, we can expect massive losses unfortunately, of very precious animals we've got today," Professor Archer said.
Animals likely to become extinct
UNSW biology lecturer Dr Karen Black said the animals most susceptible to becoming extinct from climate change were more specialised animals from particular environments.
"The koala for example, really highly specialised, arboreal, herbivore, relies on a few key species of eucalyptus," she said.
"Whereas animals that tend to be opportunistic in the things they eat, you would expect those to be able to survive."
Researchers will continue to study the markings on the enamel of the Nimbadon's teeth to determine is diet.
"That will help us understand what they were actually eating while they were up in those tree tops," Professor Archer said.
"A similar animal like sloths … is a leaf eater but these drop bears, these Nimbadons, were not. They were eating something else."
