The biggest-ever graveyard of an ancient rhino-sized mega-wombat called diprotodon was discovered by Australian scientists yesterday.

And it is believed that the site is potentially holding valuable clues on the species’ extinction.

The remote fossil deposit in outback Queensland state is thought to contain at least 20 diprotodon skeletons including a huge specimen named Kenny, whose jawbone alone is 70 centimetres long.

Scientist 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 of the species unearthed.

The graveyard contained the largest concentration of mega-wombat fossils ever discovered in Australia and could hold important clues on how the diprotodon lived and what caused it to perish.

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 same time indigenous tribes first appeared.

Human and climate triggers are hotly debated.

Dr Hocknull said the remains of hundreds of tiny fish, frogs, lizards and mammals have also been found at the site, which he described as important a discovery as the mega-wombat bones. “They will allow us to reconstruct what the environment was like when these giants were alive, and more importantly, what has changed to the ecosystem since then,” he said.

A relative of the modern-day wombat, the herbivorous diprotodon was just one of a host of megafauna to roam ancient Australia including towering kangaroos and gigantic crocodiles.

It was the size of a rhinoceros, pigeon-toed and had a backward-facing pouch.

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.