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22-Mar-2012

Contact: Science Press Package
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American Association for the Advancement of Science

The extinction of Australia's giant animals



An extinct marsupial mega-herbivore, Diprotodon optatum. Drawing by Peter Murray.
[Image Science/AAAS]

Human hunters were primarily responsible for the disappearance of Australia's giant vertebrates about 40,000 years ago. And, this extinction in turn caused major ecological changes. These are the conclusions of a new study in the 23 March 2012 issue of the journal Science.

Susan Rule of the Australian National University in Canberra, Australia and colleagues analyzed pollen and charcoal in two sediment cores from tropical Australia.

They report that Sporormiella spores, which grow in herbivore dung, virtually disappeared around 41,000 years ago, a time when no known climate transformation was taking place. Instead, it appears that humans, who arrived in Australia around this time, hunted the giant marsupials, monotremes and other large animals of this time period to extinction.

Based on other changes in pollen and charcoal remnants, the authors also detected a transition from mixed rainforest to leathery-leaved, scrubby vegetation called "sclerophyll," and an increase in fire activity. But, these changes to the landscape took place after the animal extinctions, indicating that they were the result of the extinction and not its cause.

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