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Giant bones found

2002-07-31 14:14

Perth - Skeletal remains of giant kangaroos, wombats and flesh-eating marsupial lions discovered by accident in deep sinkholes in the Australian outback may be 1.6 million years old, scientists said on Wednesday.

The prize among a treasure trove of bones stumbled upon by adventure seekers is a near perfect skeleton of a marsupial lion, called Thylacoleo Carnifex, or Leo, thought to have died out 46 000 years ago - roughly the same time that humans are thought to have first reached the Australian continent.

Scientists are hoping the discovery of so-called megafauna will help fill in gaps on the origin of the thylacoleo carnifex and its relationship with other marsupials as well as the precise date of their extinction.

The area where the fossils were found, along the remote Nullarbor Plain in Western Australia state overlooking the Great Australian Bight, has been sealed off.

The exact location is being kept a secret while palaeontologists prepare more abseiling expeditions into the dark sinkholes in search of more bones. "This is the most amazing collection of mass skeletons that I have ever seen," said expedition leader John Long, curator of vertebrates for the Western Australian Museum.

"It's like a crime scene," he said. "We don't want anything contaminated," said Long, who is writing a book on fossil thieves.

Radiation levels in the caves were measured to help date the bones accurately, and samples have been sent to England's Oxford university for DNA testing, Long said.

The bones of seven other types of extinct animals, including a pony-sized wombat and possibly the largest remains of a kangaroo, more than three metres (16 feet) high, were also found.

The Nullarbor contains numerous sinkholes and caves, some rich in fossils. Over time the sinkholes became death traps for animals that fell in and died.

The dry dark conditions of such tombs ensured that remains were well preserved, enabling scientists to extract DNA samples from traces of soft tissue, hair and blowfly remains, for dating and forensic testing, Long said.

Long said the cache might have gone undetected but for a group of cavers who first abseiled into the holes in search of uncharted adventure last May.

"Thankfully, they left everything intact and were aware of the fragility of the bones and the possibility of contamination," Long said.

Some of the striking "Leo" features have led scientists to conclude the species was a voracious pouched carnivore, far removed from any of the cuddly looking creatures which now inhabit Australia.

It would have been equipped with a spectacular pair of piercing lower incisors and huge teeth used to tear into the flesh of unfortunate prey. Curiously, the limbs are adapted for climbing and grasping rather than for running.

"The paws are well armed with retractable claws and the hands have large opposable thumbs," Long said.

Presumably it ate ground-dwelling plant eaters, such as the giant leaf-eating kangaroo. Like modern lions and leopards, Leo would have clamped the prey's neck and windpipe in its jaws, killing by suffocation. The skeleton of this marsupial pouched lion is on display in a hastily arranged display at the museum in Perth.