The fossilised ankle bone of a carnivorous dinosaur found on the Victorian coast in 2006 is the first evidence that a major group of dinosaurs called this part of the world home.
Until now, scientists thought the distribution of the ceratosaur group of dinosaurs was limited to western Gondwana - present day South America, Africa, India and Madagascar. However, the fossil find in Victoria, outlined in the journal Naturwissenschaften this week, shows that eastern Gondwana - of which Australia was a part - was a melting-pot for dinosaur diversity during the cretaceous period.
Museum Victoria palaeontologist Erich Fitzgerald, the lead author on the paper, said: ''Until now there had been no record [of the ceratosaur group] from Australia, so this discovery really plugs one of the biggest gaps in our dinosaur record.''
Dr Fitzgerald said the dinosaur group joined a growing and ''surprisingly varied'' list of predatory dinosaurs found in Australia compared to other southern continents. ''That diversity can perhaps only be explained, given our geographic isolation, by the probability that these predatory dinosaur groups made it to Australia early on in their history before the continents started to split apart.''
Other carnivorous dinosaurs known to have lived in Australia about 100 to 125 million years ago include tyrannosaurs, spinosaurids and allosaurs. Each group can be traced as far back as 170 million years, when all the globe's continents were still connected, meaning that dinosaurs could walk freely between continents.
Dr Fitzgerald said this was important because it suggested that the dinosaurs found in Australia may not have evolved in isolation. Instead, they may represent dinosaurs which had evolved much further back in time.
''You could describe Australia as almost being like a Jurassic Park in terms of its carnivorous dinosaurs, because the groups of predatory dinosaurs we have are groups that have their origins in the Jurassic period,'' he said.
The fossilised left ankle bone was found in grey sandstone at San Remo, 87 kilometres south-east of Melbourne. Dr Fitzgerald said this indicated that the adult animal had died near water about 125 million years ago. He said features on the ankle bone - measuring six centimetres wide and five centimetres high - showed it belonged to a member of the ceratosaur group, three-toed dinosaurs standing between one and two metres tall.