KEY POINTS:
Large, carnivorous dinosaurs roamed southern Australia 115 million years ago, when the continent was joined to Antarctica, and were padded with body fat to survive temperatures as low as minus 30 degrees Celsius.
Standing about 3.7 metres tall, these hardy creatures inhabited the area close to the South
Pole for at least 10 million years during the Cretaceous period, an expert said.
Palaeontologists from Australia and the United States came by their findings after uncovering three separate fossil footprints measuring about 36 cm long, each with at least two or three partial toes.
The footprints were found close to the shoreline in Victoria, Australia, in February 2006 and February 2007.
"(They are) the biggest carnivores we have from polar southeastern Australia ... in other words (large) dinosaurs could live in these unusual environments," said Thomas Rich, curator of vertebrate palaeontology at the Museum of Victoria.
"We have had evidence of small ones ... but we didn't have any evidence of the really big ones until this came along," Rich said in a telephone interview on Tuesday.
Australia was once part of the southern supercontinent of Gondwana, which also included South America, Africa, India and Antarctica. Gondwana began to break up about 120 million years ago and Australia separated from Antarctica about 50 million years ago and began moving northwards.
Rich said the area that the creatures roamed was far from hospitable, with winter temperatures plunging to minus - 30 degrees Celsius, although summer temperatures reached around 20 C.
"It wasn't the steamy jungle that people picture for dinosaurs ... they might have had a lot of body fat. We think they were warm-blooded," Rich added.
From the size of their feet, the experts figured they were up to 1.5 metres high at the hip.
"You are talking about an animal that's about 3.7 metres tall, or about the size of a small adult tyrannosaurus," Rich said.
A fully mature tyrannosaurus, one of the largest land carnivores of all time, could be up to 6.1 metres tall.
The findings were presented at a recent meeting of the Society of Vertebrate Palaeontology in Texas.
The experts believe these large animals existed for at least 10 million years based on earlier evidence of polar dinosaurs found nearby.
"We have polar dinosaurs in another area just to the west where these (three) footprints occurred, which is about 105 million years. So we think they existed for at least 10 million years," Rich said.
- REUTERS