Dec. 16, 2008 -- Australia's iconic koala is not a dwarf and the finding has major implications for theories on what happened to the continent's prehistoric megafauna, a Queensland palaeontologist said. Gilbert Price, of the University of Queensland's Center for Microscopy and Microanalysis, said there has been a long-held view that modern koalas were a dwarf version of the giant prehistoric koala that lived between 30,000 and 700,000 years ago. However, in a paper published in Quaternary Science Reviews, Price said modern koalas are a separate species that at times coexisted with the Late Pleistocene giant Phascolarctos stirtoni, which weighed between 20 and 30 kilograms. Gilbert used improved dating techniques to analyze fossils and found that between 300,000 and 500,000 years ago the two koalas were both living in Australian trees. Related Content: Koala at Risk for Extinction ABC Science Online How Stuff Works: Koalas "It's fascinating that up until fairly recently in geological terms we did have two types of koalas kicking around," said Gilbert. "The fossil records do suggest that they lived in the same place at the same time [perhaps] there is something about their sizes that allowed them to fill a slightly different ecological niche. "The big question is why one koala species survived past 50,000 years ago and the other didn't make it." Gilbert said understanding this may help prevent the modern-day koala from becoming extinct. However he said a lack of well-dated fossil records makes it difficult to determine the true ancestor of the modern koala. He said his finding also suggests that the debate about why Australia's megafauna became extinct need to be revisited. "My work shows we've got to sort out this dwarfing hypothesis first," he said. The "dwarfing hypothesis" was originally developed to explain the body-size relationship between extinct Pleistocene mammalian megafauna and smaller-sized, similar-looking, modern-day animals, said Gilbert. It has been applied to other present-day Australian mammals including the grey kangaroo, Tasmanian devil and the koala. Gilbert said the dwarfing phenomena has been used to support opposing megafauna extinction theories. Get More NewsMouse Cloned From Long-Frozen CellResearchers create a mouse from a long-frozen cell. Will the mammoth be next?'Bubble' Could Protect AstronautsScientists say a "bubble" around a Mars-bound spaceship could protect astronauts.Big Reduction of Snowmobiles in Yellowstone ProposedA new plan would cut snowmobile use by 40 percent in Yellowstone.Microbes: Fuel of the Future?A reddish South American microbe is literally breathing fuel, say scientists.DNA Links Remains to Steve FossetDNA tests on two bones found in California confirm they are those of Steve Fossett.Women Carry More Bacteria Than MenSome bacteria prefer women, suggests a new study. But why?Ancient 'Water Monster' Facing ExtinctionA foot-long salamander that was a key part of Aztec legend is threatened by extinction.Grand Canyon's Youth ConfirmedThe Grand Canyon is millions of years younger than previously thought, argue geologists.My Take: E-Voting Not User FriendlyOpinion: Electronic voting machines don't always capture the intent of voters.SLIDE SHOW: Landscapes of TerrorWhat makes a place feel scary? There are scientific explanations.At 40, Brain and Body SlowThe part of the brain in charge of motion starts a gradual slide in middle age.Spiders, Scorpions Among World's Oldest CreaturesMany creepy crawlies have been on Earth much longer than previously believed.Blood-Sucking Vampire Bats Sing DuetsWhite-winged vampire bats "harmonize" with separated roost mates. |
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