Dr Gavin Prideaux, paleontologist for Western Australian Museum and Flinders University, publishes an article in international journal Geology's January 2007 edition that is certain to fuel what has become one of palaeontology's longest-running and contentious debates.
The latest study is unique in providing a long-term perspective on the responses of the megafauna in the Naracoorte Caves region of south-eastern Australia to cyclical swings in Ice Age climates.
Australia lost 90% of its large fauna, including rhino-sized marsupials, 3-metre tall kangaroos and giant goannas within 20 thousand years of human arrival. Opinions are divided between the relative importance of climatic changes and the activities of humans themselves via habitat disturbance or over-hunting. Unfortunately, the debate has been hamstrung by a lack of basic data on how communities responded to climate changes before humans arrived.
Based on The Geological Society of America's Geology paper:
"Mammalian responses to Pleistocene climate change in southeastern Australia"
by Gavin J. Prideaux, , Richard G. Roberts, Dirk Megirian, Kira E. Westaway, John Hellstrom, Jon M. Olley
Abstract: http://dx.doi.org/10.1130/G23070A.1
Resolving faunal responses to Pleistocene climate change is vital for differentiating human impacts from other drivers of ecological change. While 90% of Australia's large mammals were extinct by ca. 45 ka, their responses to glacial-interglacial cycling have remained unknown, due to a lack of rigorous biostratigraphic studies and the rarity of terrestrial climatic records that can be related directly to faunal records. We present an analysis of faunal data from the Naracoorte Caves in southeastern Australia, which are unique not only because of the species richness and time-depth of the assemblages that they contain, but also because this faunal record is directly comparable with a 500 k.y. speleothem-based record of local effective moisture. Our data reveal that, despite significant population fluctuations driven by glacial-interglacial cycling, the species composition of the mammal fauna was essentially stable for 500 k.y. before the late Pleistocene extinctions. Larger species declined during a drier interval between 270 and 220 ka, likely reflecting range contractions away from Naracoorte, but they then recovered locally, persisting well into the late Pleistocene. Because the speleothem record and prior faunal response imply that local conditions should have been favorable for megafauna until at least 30 ka, climate change is unlikely to have been the principal cause of the extinctions.
I'm not how compelling the argument is, but it has been debated that the poorer soils of Australia couldn't support the larger herbivores. Given the vast size of the continent, you'd think the massive beats would just roam further afield. The debate is certainly stilll hot, but it looks as though the rise of human hunting, local competition for resources, perhaps poorer soils and in some part, climate change across the globe, played a role.
Great article, Cash.