Archives of The Cold Blooded News

The Newsletter of the Colorado Herpetological Society

Volume 32, Number 8;   August, 2005

Small Species Back Up Giant Marsupial Climate Change Extinction Claim

Thinking small in a time when everything was big has helped Queensland researchers to unearth new evidence that climate change, instead of humans, was responsible for wiping out Australian giant marsupials or megafauna 40,000 years ago. Instead of only excavating 'trophy specimens' such as giant kangaroos and wombats, the researchers from Queensland University of Technology (QUT) and Queensland Museum performed the first systematic analysis of a site in the fossil rich Darling Downs region of south-eastern Queensland.

Reported in the journal Memoirs of the Queensland Museum tomorrow (Tuesday 31 May), they found smaller species, dependent on a wetter environment, had also disappeared. By systematically analysing a 10 metre deep section of creek bed, the team uncovered 44 species, ranging from land snails, frogs, lizards, and small mammals to giant wombats and kangaroos, including many species previously unknown to have occurred in the Darling Downs fossil record. The findings, which were unearthed with the help of amateur fossil hunter, Ian Sobbe, are of particular significance because the Darling Downs fossil deposits are among the youngest Australian megafauna deposits - laid down on the cusp of the extinction event.

The Darling Downs contain some of the most extensive and significant Pleistocene megafauna deposits in Australia, but because it's been excavated since the 1840s, it was assumed that the palaeoenvironment record was well established. Closer examination revealed a bias in sample collection in favour of larger animals, and there had been few attempts to document ecological and sediment data. The dig also failed to unearth evidence of human activity, suggesting they didn't inhabit the region at the same time as megafauna.