Post by jonsdigs on Dec 25, 2006 22:59:46 GMT -5
Climate change didn't kill megafauna
By Jane Bunce
The Australian
December 26, 2006
AUSTRALIA'S giant prehistoric animals were killed off by humans, not climate change, new research indicates.
Ninety per cent of Australia's so-called megafauna - prehistoric animals such as giant goannas, three-metre tall kangaroos and rhino-sized marsupials - died out within 20,000 years of human arrival.
But the lack of data from the years preceding human arrival has made it difficult to determine whether environmental changes or human hunting and habitat destruction killed off the giant animals.
The new research, published in international journal Geology's January 2007 edition, is set to fuel what has become one of palaeontology's longest-running and contentious debates.
The researchers examined how the giant animals responded to climate change in the years before humans arrived.
An analysis of fossils found in south-eastern Australia found they became extinct during environmental conditions similar to those under which they thrived.
The scientists dated fossils found in the Naracoorte Caves World Heritage Area in southeastern South Australia, which contain the country's richest collection of Pleistocene fossils dating back 1.8 million to 10 thousand years.
They compared the fossil data to a 500 thousand-year record of local rainfall, which was determined by analysing the caves' stalagmite system, and additional climate clues found in the sediments.
The fossil evidence revealed "surprising stability" in the mammal composition in successive periods of wet and dry, Western Australian Museum and Flinders University palaeontologist Dr Gavin Prideaux said.
"Climate change was certainly not the main culprit in the extinctions,'' Dr Prideaux said.
"Our data show that the megafauna was resilient to climatic fluctuations over the past half-million years.
"Although populations fluctuated locally in concert with cyclical climatic changes, with larger species favoured in wetter times, most if not all of them survived even the driest times - then humans arrived.''
The Naracoorte giants perished under climatic conditions similar to those under which they previously thrived, the researchers concluded, strongly implicating humans in their extinction.
Article
By Jane Bunce
The Australian
December 26, 2006
AUSTRALIA'S giant prehistoric animals were killed off by humans, not climate change, new research indicates.
Ninety per cent of Australia's so-called megafauna - prehistoric animals such as giant goannas, three-metre tall kangaroos and rhino-sized marsupials - died out within 20,000 years of human arrival.
But the lack of data from the years preceding human arrival has made it difficult to determine whether environmental changes or human hunting and habitat destruction killed off the giant animals.
The new research, published in international journal Geology's January 2007 edition, is set to fuel what has become one of palaeontology's longest-running and contentious debates.
The researchers examined how the giant animals responded to climate change in the years before humans arrived.
An analysis of fossils found in south-eastern Australia found they became extinct during environmental conditions similar to those under which they thrived.
The scientists dated fossils found in the Naracoorte Caves World Heritage Area in southeastern South Australia, which contain the country's richest collection of Pleistocene fossils dating back 1.8 million to 10 thousand years.
They compared the fossil data to a 500 thousand-year record of local rainfall, which was determined by analysing the caves' stalagmite system, and additional climate clues found in the sediments.
The fossil evidence revealed "surprising stability" in the mammal composition in successive periods of wet and dry, Western Australian Museum and Flinders University palaeontologist Dr Gavin Prideaux said.
"Climate change was certainly not the main culprit in the extinctions,'' Dr Prideaux said.
"Our data show that the megafauna was resilient to climatic fluctuations over the past half-million years.
"Although populations fluctuated locally in concert with cyclical climatic changes, with larger species favoured in wetter times, most if not all of them survived even the driest times - then humans arrived.''
The Naracoorte giants perished under climatic conditions similar to those under which they previously thrived, the researchers concluded, strongly implicating humans in their extinction.
Article