Bone find in caves could yield new species of long-extinct giants

Recently discovered caves containing the bones of long-extinct giant kangaroos, wombats the size of cars and prehistoric marsupial lions could yield new species of megafauna - giant animals that once roamed Australia, say palaeontologists.

The three limestone caves, on the remote Nullarbor Plain in southern Australia, were discovered in May by cavers who had been using microlight aircraft to look for underground systems to explore.

The treasure trove of fossils, believed to be more than one million years old, was excavated by a team led by John Long of the Western Australian Museum in Perth. Dr Long said among the most important finds was the complete skeleton of a marsupial lion, the first ever discovered.

The animal was about the size of a leopard and is believed to have been one of the most ferocious predators that ever lived, with large teeth and retractable claws for disembowelling prey. It also had a pouch, like today's koalas and kangaroos.

Dr Long said: 'We've got a number of animals out there that are very unusual, some of which, when we study them further, are almost certainly going to be new species.

'It's a very significant discovery in terms of filling out the picture of the sorts of animals that lived in the Nullarbor region.

Scientists also found the jawbones of a giant short-faced kangaroo, which would have stood three metres tall, and the remains of wallabies which had horn-like ridges over their eye sockets and sharp, sickle-shaped claws. They also unearthed fossils from two Tasmanian tigers, a creature which only became extinct in the 1930s.

Megafauna developed in Australia a million years ago and died out around 40,000 years ago. Scientists are divided as to what pushed them to extinction.

Dr Long said: 'There are two theories. One is that the arrival of humans in Australia about 60,000 years ago began the collapse of the megafauna through hunting. The other is simply climate and vegetation change.'

Robert Jones, a palaeontologist from the Australian Museum in Sydney, said: 'It wasn't just Australia that had megafauna. North America had mammoths, Europe had cave bears and cave lions, and Africa still has elephants and rhinos.'

The animals died when they stumbled into the cave and were unable to get out. Their skeletons were preserved by the dark, dry conditions.

The Nullarbor Plain, which stretches for 1,200km between South Australia and Western Australia, is honeycombed with caves, and scientists believe more fossils are waiting to be discovered.

'There's likely to be a lot more out there,' Mr Jones said.