Australian scientists Thursday unveiled the biggest-ever graveyard of an ancient rhino-sized mega-wombat called diprotodon, with the site potentially holding valuable clues on the species' extinction.
The remote fossil deposit in outback Queensland state is thought to contain up to 50 diprotodon skeletons including a huge specimen named Kenny, whose jawbone alone is 70 centimetres (28 inches) long.
Lead scientist on the dig, Scott Hocknull from the Queensland Museum in Brisbane, said Kenny was one of the largest diprotodons he had ever seen and one of the best preserved specimens.
Pigeon-toed and with a backward-facing pouch large enough to carry an adult human, Hocknull likened diprotodon to "a cross between a wombat and a bear but the size of a rhinoceros".
The deposit contained the largest concentration of mega-wombat fossils ever discovered and could hold important clues on how the diprotodon lived and what caused it to perish, he said.
"When we did the initial survey I was just completely blown away by the concentrations of these fragments," he told AFP by telephone from the far-flung desert dig site, which he estimated at between 100,000-200,000 years old.
"It's a paleontologists' goldmine where we can really see what these megafauna were doing, how they actually behaved, what their ecology was.
"With so many fossils it gives us a unique opportunity to see these animals in their environment, basically, so we can reconstruct it."
The mega-wombats appeared to have been trapped in boggy conditions at the site after seeking refuge there from extremely dry conditions during a period of significant climate change in ancient Australia, he added.
Diprotodon, the largest marsupial ever to roam the earth, weighing up to 2.8 tonnes, lived between two million and 50,000 years ago and died out around the time indigenous tribes first appeared.
Human and climate triggers for its disappearance are hotly debated.
A huge array of other animal bones have also been found at the site, including the teeth of a six-metre long venomous lizard called megalania and the teeth and bony back-plates of an enormous ancient crocodile.
"We're almost certain that most of these carcasses of diprotodon have been torn apart by both the crocodiles and the lizards, because we've found shed teeth within their skeletons from both animals," Hocknull said.
Towering super-kangaroos up to 2.5 metres tall called protemnodon have also been discovered at the location, along with the remains of tiny frogs, rodents and fish -- an important find in what is now an extremely arid region.
"Very little is known about arid zone fish and their evolution, and finding a fossil record for them is amazing," said Hocknull.
A relative of the modern-day wombat, the herbivorous diprotodon was just one of a host of megafauna to roam ancient Australia including the tree-sized kangaroos and gigantic crocodiles.
Megafauna are thought to have evolved to such large sizes to cope with inhospitable climates and food scarcity, with fossils found in Australia of prehistoric emus, tree-dwelling crocodiles and carnivorous kangaroos.
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