Land of the giants

Katherine Smith, ScienceAlert 17 Aug 09;
University of Melbourne

The first humans coming to Australia some 65,000 years ago came face-to-face with giant goannas and wombats the size of motor vehicles.

Herds of overgrown wombats the size of a Toyota RAV 4, horned tortoises as big as a Volkswagen, and short-faced kangaroos that hopped nimbly about on two feet munching on treetops are among the creatures that emerge rather alarmingly from the pages of Dr Danielle Clode’s new book about the Australian Pleistocene.

Prehistoric Giants: the Megafauna of Australia, tells the story of the giant animals that once inhabited the massive, forest-fringed continent that comprised the Australian mainland, all of what is now New Guinea and the Torres Strait, and extended across the Bass Strait to encompass Tasmania.

“When people first spread across Australia around 65,000 years ago, they would have come face to face with a very different suite of large animals from the ones we have today,” she says.

So while the human species was busily evolving in Africa and spreading across the globe, megafauna appeared in Australia, growing in scale over the period of the Pleistocene, until giant goannas and crocodiles terrorised the land, looking for food and possibly using their vast heads as wrecking balls on each other, before a sudden extinction.

Based in the Department of Zoology at the University of Melbourne, Dr Clode began her career with a doctorate in animal behaviour, and says one of her main enthusiasms is the ‘behaviour of dead animals’.

The book has been created with artwork by Peter Trusler that helps bring these animals to life, and is intended for middle school students, or anyone who is interested in learning about Australia’s megafauna.

Dr Clode says that what gave rise to the era of megafauna is unknown, and the cause of their extinction “even more contentious”.

“There have been a great many weird and wonderful beasts on Earth in the past, but the megafauna were so close – they seem to have existed within human history – and it is this relative proximity that makes the lives and demise of these great beasts so fascinating,” she writes.

Dr Clode explains that it’s too simplistic to attribute this extinction to humans, at least directly, despite strong “circumstantial evidence” against the species. “Wherever humans went, megafauna disappeared.”

She says what is clear from the history of extinction of species in both prehistoric and modern times is that some species are more vulnerable to environmental change than others.

“Large species, slow-breeding species, specialist species and isolated species are all vulnerable to extinction when their environment changes. And the one feature that characterises humans above all else is their remarkable ability to change the environment, including the climate, whether intentionally or not.”