Humans, not climate, sounded death knell of giants

January 25th, 2010 - 3:05 pm ICT by IANS  

Sydney, Jan 25 (IANS) Human beings, not climate change, caused the death of Australia’s megafauna, giant marsupials, huge reptiles and flightless birds, at least 40,000 years ago.
The megafauna included giant kangaroos, birds and less familiar creatures, says a study co-authored by University of Adelaide researchers.

They claim that improved dating methods show that humans and megafauna only co-existed for a relatively short time after people inhabited Australia, adding weight to the argument that hunting led to the extinction of large species.

Richard ‘Bert’ Roberts and Barry Brook, professors from the Universities of Wollongong and Adelaide, said new methods to directly date bones and teeth of extinct species show that megafauna fossils and Aboriginal tools do not all date from the same period.

“Debate about the possible cause of these late Pleistocene extinctions has continued for more than 150 years, with scientists divided over whether climate change or the arrival of humans has been responsible for their demise,” Brook says.

“Australia was colonised during a time when the climate was relatively benign, supporting the view that people, not climate change, caused the extinctions here,” he says. But a site in New South Wales, Cuddie Springs, stood out as an anomaly.

Fossils of giant kangaroos, giant birds and the rhino-sized Diprotodon (the largest marsupial ever to roam Australia) were found in the same sedimentary layers as stone tools, leading scientists to previously claim “unequivocal evidence” of a long overlap of humans and megafauna.

However, Roberts, who led the study says direct dating of fossils shows that the artefacts and megafauna fossils at the Cuddie Springs site were mixed together over many thousands of years, long after the giant animals had died.

“These results provide no evidence for the late survival of megafauna at this site,” Roberts says, according to a University of Adelaide release.

“Given that people arrived in Australia between 60,000 and 45,000 years ago, human impact was the likely extinction driver, either through hunting or habitat disturbance,” he says.

These findings were published in Science.

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