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Extinct marsupial cats were real whoppers!


Thylacoleo, the marsipial lion, bigger than previously realised. Picture credit Anne Musser.

New size estimates for the marsupial 'lion' of Australia, which went extinct over the last 50 000 years, suggest that it was much bigger than previously thought.

The new giant size range for Thylacoleo carnifex casts some doubt on theories concerning the evolution of Australia's environment.

A small team of palaeontologists headed by Steve Wroe from the University of New South Wales has been reassessing the mass of the extinct carnivore by measuring its leg bones.

There is a relationship between the mass of an animal and the circumference of the humerus and femur. By measuring the circumferences of humeri and femora from sites in New South Wales and South Australia, Wroe and his team were able to calculate the mass of the animals when they were alive.

Using complete skeletons of Thylacoleo carnifex, Wroe's team estimate that it weighed between 84 kg and 129 kg. By extrapolating their data to include isolated skulls from much larger animals, the team concluded that an upper size range of 260 kg was possible for the species.

These masses compare favourably with lions and tigers. Previous size estimates for Thylacoleo suggested a much more spritely animal, similar to a leopard.

Wroe claims that these new findings contradict a recent theory from Dr Tim Flannery of the Australian Museum. Flannery contends that Australia could not support large mammalian carnivores because the environment was too poor in nutrients.

"It has been suggested that big mammalian predators could not exist in Australia because there wasn't enough food for them." Wroe explained. "But these new measurements show that Thylacoleo was a big kick-arse carnivore by any standard, blowing the old theory right out of the water."

Tags: environment