Been busy with real life matters, hence the lack of posts. However, I came across this story from ABC Science about … well, it touches on several different topics. It seems well worth a quick read.
Palaeontologist Dr Steve Salisbury from the University of Queensland in Brisbane, and colleagues, say a forearm bone from a meat-eating dinosaur first found in 1989 is likely to be related to a Megaraptor from Argentina.
This is the first evidence linking Australian dinosaurs to those in other Gondwanan continents, rather than from the northern hemisphere, say the researchers in today’s issue of the Proceedings of the Royal Society B.
“We really need to take a closer look at what we’ve previously identified our dinosaurs as,” says Salisbury, whose study centred on a forearm found at Dinosaur Cove, Cape Otway, south-west of Melbourne.
Salisbury says Australian dinosaurs have generally been considered an odd breed of their own, descended from northern hemisphere ancestors and evolved in isolation.
Not only were they cut off from the north when Pangea broke up, but they were also cut off from the rest of Gondwana by some means – perhaps the harsh climate of Antarctica or a mountain range.
Salisbury says this conclusion was based only on comparing Australian fossils with those in the northern hemisphere, since there were few fossils available from other parts of Gondwana itself.
In recent years, there has been a “surge of discoveries” in Africa and South America, which have shed new light on the matter.
Salisbury says he and colleagues in Argentina and the US saw a close similarity between the Australian fossil and the remains of a dinosaur from Argentina called Megaraptor.
“The [Australian] fossil is almost indistinguishable from fossils of Megaraptor known from Argentina so much so that we’re tentatively referring to it as the same genus,” he says.
He says the finding that dinosaurs moved freely across Gondwana, including into Australia, is supported by other observations.
“For a few years now we’ve known that the same types of dinosaurs that you see in South America also occur in India and Madagascar,” says Salisbury.
“To have that happen they’ve got to be moving through Antarctica. And if they’re moving through Antarctica they’re essentially moving past the entrance to Australia.”
Professor Patricia Vickers-Rich of Monash University in Melbourne disagrees that the findings dispel the current theory.
“Unfortunately, this single bone, which our team collected long ago, is damaged and the conclusions being drawn from it are beyond what we feel are justified,” she says.
“More, and less fragmentary, material is needed before assertions such as are made in this paper can be taken scientifically seriously,” she says.
Salisbury agrees working with a forearm bone alone is tricky, but he is pretty sure the Australian dinosaur is related to Megaraptor, if only through a common ancestor that wandered across Gondwana.
He says the dead give-away was the unusually large elbow on the forearm found in Australia.
“No other dinosaurs have got a forearm that looks like Megaraptor’s so when we find a forearm bone in Australia that matches Megaraptor the simplest explanation is that it is Megaraptor,” Salisbury says.
The team also checked the Australian fossil against all comparable fossils from around the world.
“To be certain we’ve pretty much compared it to every single forearm of a meat-eating dinosaur that we can find,” he says.
He says palaeontologists should now focus on comparing Australian dinosaurs with other fossils from Gondwana rather than examining material from North America or China.
Salisbury also says the findings have implications for the origin of Australian mammals.