News Archive

The arrival of humans was probably decisive in the extinction of the megafauna living in WA's South West 40,000 years ago, though climate change and fire may have contributed, according to new research.

Fossils of animals ranging from tiny 30g native mice to giant 500kg marsupials called diprotodontids , which are unlike anything living now, have been recorded in a cave in the Leeuwin-Naturaliste region.

The cave sediments contain the richest fossil fauna from the western two-thirds of the Australian continent, and provide the best record on earth of how 90 per cent of the larger mammal species became extinct shortly after the first humans arrived.

Published in this week's Proceedings of the National Academy of Sciences of the United States of America, the findings suggest that one-factor explanations for the extinctions are over-simplistic.

The research team included researchers from the Universities of Western Australia, Wollongong, Melbourne, Flinders University and the Australian National University, as well as a scientist working with the Augusta-Margaret River Tourism Association.

They sampled fossils from Tight Entrance Cave and found that within 10 millennia of human arrival, all larger animals except the grey kangaroo and the thylacine became extinct.

Included in the fossil record are Tasmanian devils and tigers, several kinds of bandicoots, wallabies (including a 166kg giant wallaby) and kangaroos, koalas, quokkas, echidnas, possums and native rats and mice. There was also a leopard-sized marsupial lion.

The fossils revealed that ancient faunas bounced back from natural climate change, recorded in the cave sediments, before people arrived in the region 50,000 years ago. But soon after first human occupation, the once diverse community collapsed.

Researcher Aidan Couzens, who participated in the study as part of his Honours degree in 2007 at The University of Western Australia, said the research was significant because it was the first study at a single site which addressed the three competing hypotheses about megafauna extinction.

"These hypotheses are that human hunting, landscape burning and climate change led to megafauna becoming extinct," Mr Couzens said. "We show that the megafauna extinction, in both pattern and timing, corresponds much more closely with human arrival than with any changes in the ancient environment."

One of the fossils, a giant rat kangaroo (Potoroine) was named after researcher Lindsay Hatcher, who works with the Augusta-Margaret River Tourism Association.

Media references

Aidan Couzens   (+61 4) 39 963 879

Janine MacDonald (UWA Public Affairs)  (+61 8)  6488 5563 / (+614) 32 637 716