Washington, Dec 16 (ANI): A palaeontologist has determined that 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.
The palaeontologist in question is Dr Gilbert Price, of the University of Queensland's Centre for Microscopy and Microanalysis, in Australia.
The long-held view is that modern koalas were a dwarf version of the giant prehistoric koala that lived between 30,000 and 700,000 years ago.
However, Price said that modern koalas are a separate species that at times co-existed with the Late Pleistocene giant Phascolarctos stirtoni, which weighed between 20 and 30 kilograms.
Price 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.
"It's fascinating that up until fairly recently in geological terms we did have two types of koalas kicking around," he said.
"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," he added.
"The big question is why one koala species survived past 50,000 years ago and the other didn't make it," Price wonders.
According to him, understanding this may help prevent the modern-day koala from becoming extinct.
He said that 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.
It has been applied to other present-day Australian mammals including the grey kangaroo, Tasmanian devil and the koala.
Price said that the dwarfing phenomena has been used to support opposing megafauna extinction theories.
He said that on one side, dwarfing is viewed as the result of a physiological response to climate-induced changes in habitat and food supplies, while the counter view holds that it was human induced through targeting of larger animals in hunting.
However, Price said his study shows that dwarfing itself "has not been fully tested".
"A combination of more intensive physical dating, better stratigraphic control in regard to collecting methodologies, and up-to-date taxonomic information is critical for testing such hypotheses," he said. (ANI)