Giant carnivorous dinosaurs roamed freezing Australian region when it was part of Antarctica

Melbourne

Scientists have discovered that dinosaurs roamed the polar environment in southern Australia when the country was still connected to Antarctica. This was during the Early Cretaceous period when large theropod dinosaurs lived in the icy cold region and moved around the river floodplains when the ice thawed during the summers.

The revelations have been presented in a study published in the journal Alcheringa. Dinosaur tracks were recently discovered in the Wonthaggi Formation south of Melbourne and were likely made between 120 million and 128 million years ago.

The tracks belonged to 18 theropod dinosaurs and four tracks were of ornithopods, that is small, herbivorous dinosaurs that theropods likely feasted on.

Anthony Martin, first author of the study, said, “These numerous tracks are the best evidence yet that these former polar environments supported large carnivores."

"The large theropods would likely have fed on prey such as smaller dinosaurs, fish and turtles."

Martin is also a professor in Emory University’s Department of Environmental Sciences.

Theropods walked on two legs and their feet had three, clawed toes. 

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Co-authors of the study, Patricia Vickers-Rich, professor of palaeontology at Monash University, and Thomas Rich, curator of vertebrate palaeontology at Museums Victoria Research Institute, have been working for years to find fossils in the state of Victoria. 

Where Gondwana broke up 

Victoria is where the ancient supercontinent Gondwana started breaking up around 100 million years ago. Scientists say that at the time the dinosaurs lived here, the polar environment comprised a rift valley with braided rivers. During the polar winters, the region experienced deep freezing temperatures and darkness for months.

Several polar dinosaur body fossils have been found in the Wonthaggi Formation, but most of them are small fragments of bones and teeth. Earlier it was suggested that torrential spring floods likely washed them up to the region and buried them here.

But the latest discovery of tracks seems to suggest otherwise.

"Our find of so many theropod tracks, however, confirms that a variety of dinosaurs actually lived and walked on the ground where their bones were found," Martin says. "Dinosaur tracks are actually much more common at the site than we previously realised."

Co-author Melissa Lowery was the one who found more tracks mentioned in the latest study. The tracks were likely made when the dinosaurs were walking on wet sand or mud in the floodplain.