January 21, 2010
Employing improved dating methods for fossils and tools, the researchers have discovered that Australia's unique megafauna only co-existed with humans for a short time, pointing to unsustainable hunting and habitat change as the likeliest cause of the megafauna's demise.
In addition, "Australia was colonized during a time when the climate was relatively benign, supporting the view that people, not climate change, caused the extinctions here," Dr. Barry Brook, co-author of the study and professor at the University of Adelaide, says.
However researchers supporting the theory that climate change caused the megafauna's mass extinction point to a site in New South Wales, Australia, known as Cuddie Springs. Here, fossils of Australian megafauna have been found in the same sedimentary layers as human tools, leading them to proclaim unequivocal evidence that humans and Australia's megafauna overlapped for a significant period of time.
However, Professor Richard Roberts from the University of Wollongong and lead author of the study says: "these results provide no evidence for the late survival of megafauna at this site." He points out that using direct dating of the fossils and tools shows that they were mixed together over many thousands of years.
"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 concludes.
Humans - not climate - drove extinction of giant Tasmanian animals
(08/11/2008) Humans — not climate change — were responsible for the mass extinction of Australia's megafauna, according to a new study published this week in the journal Proceedings of the National Academy of Sciences.
Largest dinosaur bones in Australia discovered
(05/03/2007) The largest bones of any dinosaur known in Australia went on display at the Queensland Museum for the first time today.
Giant carnivorous marsupial beasts not killed by climate change in Australia
(01/25/2007) Humans, not climate change, caused the extinction of megafauna in Australia contends a team of Australian researchers writing in the January issue of the journal Science. Australia lost 90 percent of its largest animals, including a saber-toothed kangaroo, a marsupial lion and giant goannas, within 20,000 years of man's arrival some 50,000 years ago. Scientists have long debated whether the demise of Australian megafauna was due to human arrival, climate change, or a combination of the two factors. The new research found that the climate in southeastern Australia was little different 500,000 years ago, suggesting that climate change was not the ultimate cause of extinction.