Aussies unearth T rex

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Aussies unearth T rex

FROM: http://www.fijitimes.com/story.aspx?id=143117

Saturday, March 27, 2010

AUSTRALIAN scientists say they have discovered the first evidence that an ancestor of the mighty Tyrannosaurus rex once roamed across Australia.

The finding, published yesterday in the journal Science, fills a major gap in the evolutionary history of T rex and overturns the theory the giant predator was a purely northern hemisphere animal.

It also puts a dampener on hopes of finding a unique Australian dinosaur, says Museum Victoria curator of vertebrate palaeontology Dr Tom Rich.

The discovery is based on a pubic bone found about 20 years ago at Dinosaur Cove, 220 kilometres west of Melbourne in Victoria.

It was made after Dr Rich took a number of isolated and unidentified bones overseas for identification. Lead author Dr Roger Benson, a research fellow in the Department of Earth Sciences at the University of Cambridge, says he instantly recognised one of the bones belonged to a coelurosaur.

Coelurosaurs are the group of mainly small-bodied, predatory dinosaurs that includes birds at one end and tyrannosaurs at the other, Dr Benson says.

He says the identification was initially based on "one conspicuous feature".

Dr Benson says the far end of the pubic bone was expanded into a "boot" shape fore and aft, but was very narrow across.

"Basically, our pubis is almost identical to that of T rex, only much smaller," Dr Benson said.

The new species, which Dr Rich says would have been about one-third to one-quarter the size of T rex, shares other features with the giant predator, including short arms and powerful jaws.

"It's much more similar to T rex than one other tyrannosaur (Raptorex, from China) of slightly older age than ours."

"We know Raptorex had a robust skull and small arms and we know that our new fossil is from a tyrannosaur even more closely related to T rex. Thus it's most likely the general body plan of our new one was similar.