Wednesday, November 29, 2006

Climate change killed megafauna stars

A new report fuels speculation over just who or what is to blame for the so-called megafauna extinction.

Climate change, not Indigenous people, killed off giant kangaroos and other "megafauna" that once roamed Australia, a new study suggests. Queensland University of Technology (QUT) scientists Dr Gilbert Price and Dr Gregory Webb studied the fossil-rich Darling Downs of south-east Queensland and found large wildlife that roamed the area 40,000 years ago were drought-stressed when they died.

Aborigines were thought to have arrived in Australia about 40,000 years ago, the same time as kangaroos as tall as 2.5m, car-sized wombats, massive emus and goannas seemed to have disappeared. Dr Price said the layers of fossils in the dig area were not consistent with some theories that humans had wiped out megafauna.

"Some scientists believe in the 'blitzkrieg' megafauna extinction hypothesis, which blames humans for over-hunting these giant marsupials," he said. "If that was the case, these fossils dating back thousands of years would show the animals dying out at the same point in time. But they don't...

"These layers of fossils buried at a single site under the Darling Downs show a progressive, three-stage extinction over time that relates to periods of climate change." Dr Webb said the research had found the Darling Downs was experiencing cycles of wet and dry conditions, resulting in droughts and periodic flash flooding when megafauna populations were declining.

"The research found no evidence of humans being involved in the accumulation of fossils in the catchment at the time of deposition, but is perfectly consistent with their decline being caused by increasing aridity," he said. Dr Price and Dr Webb are researchers with QUT's School of Natural Resource Sciences and QUT's Institute of Sustainable Resources.

Earlier evidence, published in May 2005 also suggests that human intervention did not cause the extinction of Australian megafauna. Dr Price's team studied a 10 metre deep section of creek bed in the Darling Downs region. The researchers found 44 species ranging from land snails, frogs, lizards and small mammals to giant wombats and kangaroos.

The new study will be published in next month's issue of the Australian Journal of Earth Sciences.

Drought blamed for killing off the big Australians
Ancient drought blamed for megafauna destruction

Giant marsupials 'killed off by drought' -
Wikipedia: Australian_megafauna
Sparks fly in megafauna debate - ABC May 2005

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