Humanos provocaram a destruição da megafauna da Austrália

Humans Caused Demise of Australia's Megafauna, Evidence Shows

ScienceDaily (Jan. 22, 2010) — A new scientific paper co-authored by a University of Adelaide researcher reports strong evidence that humans, not climate change, caused the demise of Australia's megafauna -- giant marsupials, huge reptiles and flightless birds -- at least 40,000 years ago.

Artist's reconstruction of the half-tonne Palorchestes azael, an extinct Australian giant marsupial which was similar to a ground sloth. (Credit: Courtesy of Peter Schouten)

In a paper published in the journalScience, two Australian scientists claim that improved dating methods show that humans and megafauna only co-existed for a relatively short time after people inhabited Australia, adding weight to the argument that hunting led to the extinction of large-bodied species.

According to Professor Richard 'Bert' Roberts from the University of Wollongong and Professor Barry Brook from the University of Adelaide, new methods to directly date bones and teeth of extinct species show that megafauna fossils and Aboriginal tools do not all date from the same period.

"Debate about the possible cause of these late Pleistocene extinctions has continued for more than 150 years, with scientists divided over whether climate change or the arrival of humans has been responsible for their demise," Professor Brook says.

"Australia was colonised during a time when the climate was relatively benign, supporting the view that people, not climate change, caused the extinctions here," he says.

...

Read more here/Leia mais aqui.

+++++

Science 22 January 2010:
Vol. 327. no. 5964, pp. 420 - 422
DOI: 10.1126/science.1185517

And Then There Were None?Richard G. Roberts1 and Barry W. Brook2

Giant marsupials, reptiles, and flightless birds once inhabited Australia (see the first figure). But 23 of the 24 genera of these megafauna disappeared in the late Pleistocene (125 to 12 thousand years ago). Most Australian megafauna appear to have survived until 51 to 40 thousand years ago, with human impact by hunting or vegetation change proposed as the extinction drivers (1–4). Yet, one site has stood out as an anomaly: Cuddie Springs in interior New South Wales. Persistent claims have been made that this site contains megafauna fossils associated with stone tools in sediments deposited 40 to 30 thousand years ago (5–7), thus indicating prolonged overlap between people and megafauna. These claims have been challenged (2, 8) based on concerns about possible reworking of fossils from older deposits. To resolve this conundrum, Grün et al. (9) have now directly dated the fossils themselves. The results provide no evidence for the late survival of megafauna at the site.

1 Centre for Archaeological Science, School of Earth and Environmental Sciences, University of Wollongong, Wollongong, NSW 2522, Australia.
2 The Environment Institute, School of Earth and Environmental Sciences, University of Adelaide, Adelaide, SA 5005, Australia.

E-mail: rgrob@uow.edu.au; barry.brook@adelaide.edu.au

+++++

Professores, pesquisadores e alunos de universidades públicas e privadas com acesso ao site CAPES/Periódicos podem ler gratuitamente este artigo da Science e de mais 15.000 publicações científicas