Australian dinosaur fossil linked to South AmericaJune 15th, 2008 - 4:09 pm ICT by IANS
Sydney, June 15 (IANS) An international team of palaeontologists has identified a dinosaur fossil in Australia that had previously only been found in South America. The upper arm bone found at Dinosaur Cove in southern Victoria, shares a suite of unique features with a medium-sized predatory dinosaur from Argentina called Megaraptor, said University of Queensland palaeontologist Steve Salisbury, a team member.
He added that it was the first time that a dinosaur with unquestionable affinities to animals from other southern hemisphere continents had been recognised in Australia, ScienceDaily reported.
“Throughout much of the Age of Dinosaurs, Australia formed part of the southern super-continent of Gondwana,” Salisbury said.
“As a result, there has long been an expectation that our dinosaur fauna would show similarities to similarly aged fauna from adjoining Gondwanan landmasses, in particular Antarctica, New Zealand and South America.
“Of the Australian dinosaurs that have been recognised so far, the consensus has been that some are relics of groups that went extinct much earlier in other parts of the world, while others have been seen as early representatives of groups that are more typical of the Northern Hemisphere.
“Partly as a result, it has been proposed that Australia was somehow isolated from the rest of Gondwana, either through geographic or climatic barriers.”
Federico Angolin of the Argentinean Museum of Natural Sciences said that when the six palaeontologists on the research team independently recognised the close similarity between the Dinosaur Cove fossil and the remains of Megaraptor from Argentina, they knew they had an important discovery on their hands.
“Megaraptor is an unusual type medium-sized theropod, best known for its enormous clawed hands,” Angolin said.
“The proportionately large hand means that Megaraptor has a very distinctive forearm, which is how we were able to identify the Australian fossil.”
Said project leader Nate Smith: “The recognition of Megaraptor in Victoria provides the first definitive evidence for interchange between the dinosaur faunas of South America and Australia during the Cretaceous.
“Our results are consistent with several geological models for rifting between the southern continents during the time that these dinosaurs existed.
“This discovery indicates that we might need to rethink the long-standing claims of the northern hemisphere affinities for many Australian dinosaurs, and of geographic and/or climatic isolation of Australian dinosaur faunas.”
The results of the study have been published online through the Proceedings of the Royal Society of London.
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