Sydney, May 18 (IANS): Seven different killer dinosaurs once inhabited what is now southeastern Australia, ranging in size from cat-sized killers to a nine-metre-long T. Rex-like predator.

The discovery represents a higher than expected biodiversity of meat-eating, theropod (bird-like) dinosaur fossils from between 105 and 120 million years ago, said geoscientists and researchers from Australia's Monash University and Museum Victoria.

"We had not expected to find fossils from such a large range of dinosaur species in this area. The fossils we have collected range from tiny, cat-sized killers to Australia's version of T. Rex, a nine-metre-long predator with powerful arms and razor-sharp claws," Tom Rich from Monash University, who led the research, said.

"In total, 1,500 isolated bones and teeth of various kinds of dinosaurs have been found in Victoria so far. Their meaning is only beginning to be unravelled by detailed study and comparisons with other fossils world-wide," added Rich, the journal Public Library of Science reports.

At the time these dinosaurs ruled, southern Australia was part of the Antarctic Circle. Despite the cold, there was a high diversity of small predators, similar to the Velociraptor, featured in Jurassic Park, according to a Monash statement.

"One of the reasons for the success of small, theropod dinosaurs may be their warm-blood. As close relatives of birds, they had feathery insulation which helped maintain high body temperatures. The cool, damp climate may also explain the discovery of the same dinosaur species in both Australia and the northern continents," Rich said.

The research team included experts Lesley Kool, Dave Pickering and professor Pat Vickers-Rich.