Cold, not man, killed off Australia's megafauna, say scientists
By Chris Rodley

20 June 2006

For decades a debate has raged about what killed off Australia's megafauna - the rhinoceros-sized wombats, three-meter tall kangaroos and other prehistoric giants which once stalked the continent.

Australian megafauna

But new research by Dr Judith Field, a research fellow in the University's Australian Key Center for Microscopy and Microanalysis and a long-standing opponent of Professor Flannery, suggests that most of the megafauna had become extinct before humans arrived.

In a paper soon to be published in Quaternary Science Reviews, Dr Field and Dr Stephen Wroe from UNSW argue that most of the giant animals died out in the Ice Age which occurred 130,000 years ago, long before the appearance of humans in Australia 45,000 years ago. Their review of the available evidence indicates that only eight species of megafauna actually lived alongside humans.

"There were so few species left when humans arrived that to argue humans were responsible for effecting the extinctions is drawing a long bow," says Dr Field. "If humans did contribute to the extinction of those final eight species, it is really only a footnote to the whole process."

The two scientists argue that Australia's increasingly dry climate over the past 300,000 years created a harsh environment which contributed to the animals' gradual demise.

Adding fuel to an already heated debate, other scientists have called into question research conducted by Dr Field at Cuddie Springs in western NSW, where bones of megafauna have been found on the same level as stone tools. According to Dr Field, the Cuddie Springs site provides evidence that humans co-existed with megafauna for up to 10,000 years.

But in a paper published this month in Australasian Science, Professor Barry Brook, Dr Richard Gillespie and Professor Paul Martin argue that the site has been disturbed, causing the stone tools to be mixed in with the megafauna bones. The authors argue that cattle farmers who built a well near the site in 1876 contaminated the earth with stone tools brought in as gravel from another location.

Dr Field is unimpressed. "They are making a desperate attempt to try to dismiss the only site where megafauna and humans are found together, so that this dogma of the mass extinction 46,000 years ago can stand," she responded.

"The principle of Occam's Razor is that the simplest explanation is usually the correct one - but their explanation for how the stone tools got there is super-complicated and unsubstantiated. You may as well say aliens dropped the stones there."

The University of Sidney