Scientists have unearthed the biggest find yet of pre-historic "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.