Humans 'responsible for megafauna demise'

Melbourne, Nov 30 (ANI): Megafauna demise fossils discovered in southwestern Australia dig have suggested that climate change was not solely responsible for the demise of early giant marsupials.

The research led by Gavin Prideaux from Flinders University in South Australia has shown that many species of megafauna had survived an earlier period of extreme climate 140,000 years ago and flourished beyond it.

Prideaux and his team chose Tight Entrance Cave, near the Margaret River in south west Western Australia for their study, where the fossil record runs from 100,000 years before humans arrived, until well after they had settled in Australia.

To track how the megafauna faired over time, the researchers recorded which species were present, and then analysed snail shells from the same sediments. Shells hold a record of previous climates, with moisture and temperature affecting which isotopes are present in the shell.

"We show the megafauna were there immediately before and also really soon after the Penultimate Glacial Maximum (PGM)," ABC Science quoted Prideaux, as saying.

The PGM was a period of extreme cool dryness around 140,000 years ago.

" I think that completely knocks on the head the idea that the PGM had any kind of lasting impact on the megafauna.

"Our inference from this is that it was elevated human hunting pressure over an extended period of time that caused the extinction," he said.

Prideaux said although megafauna were large, their numbers were probably low. He also said said the arrival of humans would have had an impact on their numbers.

"Suddenly there's a new predator - and an efficient one. It doesn't really matter what the population of humans was - when people got to a particular area, they would have had some kind of effect," he said.

But, Prideaux added that although the arrival of humans was decisive in the demise of megafauna in southwestern Australia, changes in climate and fire activity might also have played a role.

The findings appeared in the journal Proceedings of the National Academy of Sciences. (ANI)