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Models Predict Location of New Megafauna Fossils

An international team of scientists has used the estimated ages and spatial distribution of Australian megafauna fossils to develop mathematical models that predict the most likely locations of undiscovered fossil deposits. Published in PLOS ONE (http://tinyurl.com/jkxh3jf), the models were developed for Australia but can be adapted for fossil-hunters in other continents.

“A chain of ideal conditions must occur for fossils to form, which means they are extremely rare, so finding as many as possible can tell us more of what the past was like, and why certain species went extinct,” says Prof Corey Bradshaw of The University of Adelaide.

“Typically, however, we use haphazard ways to find fossils. Mostly people just go to excavation sites and surrounding areas where fossils have been found before. We hope our models will make it easier for palaeontologists and archaeologists to identify new fossil sites that could yield vast treasures of prehistoric information.”

The team modelled the past distribution of species, the geological suitability of fossil preservation and the likelihood of fossil discovery in the field. They applied this information to a range of Australian megafauna that became extinct over the last 50,000 years, such as the giant terror bird Genyornis, the rhino-sized “wombat” Diprotodon and the marsupial “lion” Thylacoleo.

To produce the species distribution models of these long-extinct animals, the researchers used “hindcasted” global circulation models to predict temperature and rainfall during the deep past, and matched this with the estimated ages of the fossils.

“What we did was build a probability map for each of these layers – the species distribution, the right sort of geological conditions for fossil formation (for example, sedimentary rocks, or caves and lakes), and the ease of discovery (for example, open areas rather than dense forest),” Bradshaw says. “We combined each of these for an overall ‘suitability for fossil discovery’ map.”

The model identified areas south of Lake Eyre and west of Lake Torrens in South Australia, a large area around Shark Bay in Western Australia and other areas in the south-west of Australia as places with a high potential to yield new megafauna fossils.