Image caption Diprotodon inhabited forests and open woodland

Scientists have unearthed the biggest find yet of prehistoric "giant wombat" skeletons, revealing clues to the reasons for the species' extinction.

The find, in Queensland, Australia, of about 50 Diprotodons - the largest marsupial that ever lived - has been called a "palaeontologists' goldmine".

The plant-eating giants, the size of a rhinoceros, had backward-facing pouches big enough to carry an adult human.

The fossils are believed to be between 100,000 and 200,000 years old.

Lead scientist Scott Hocknull, from the Queensland Museum in Brisbane, said: "When we did the initial survey I was just completely blown away by the concentrations of these fragments.

"It's a palaeontologist's 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."

Ancient crocodile

The "mega-wombats" appeared to have been trapped in boggy conditions while taking refuge from dry conditions, Mr Hocknull added.

The pigeon-toed animals were widespread across Australia about 50,000 years ago, when the first indigenous people are believed to have lived, but they first appeared about 1.6 million years ago.

Big beast - Diprotodon Optatum Lived 1.6m to 40,000 years ago

Two metres tall at the shoulder

Grazed on leaves and shrubs

Closest living kin: Wombat and koala

It is unclear how or why they became extinct, but it could have been due to hunting by humans or, more likely, a changing climate.

The remote desert site contains one huge specimen, nicknamed Kenny, which is one of the best preserved and biggest examples ever discovered. Its jawbone alone is 70cm (28in) long.

The site is also home to an array of other prehistoric species, including the teeth of a 6m (20ft) lizard called Megalania and the teeth and bony back-plates of an enormous pre-historic crocodile.

Mr Hocknull said: "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."

A relative of the modern-day wombat, the Diprotodon inhabited forests, open woodland and scrub.

It was just one of several megafauna to roam pre-historic Australia.