Previously tyrannosaur fossils had only been found in northern continents, the researchers said in their findings published in Science magazine.
Compared with the ferocious Tyrannosaurus Rex made famous in the Hollywood movie Jurassic Park, which lived about 70 million years ago at the end of the Cretaceous period, the Australian T.Rex was about one-third its size and lived earlier during the Cretaceous, around 110 million years ago.
The hip bone found in the Australian state of Victoria provides the first evidence of Tyrannosaur dinosaurs in the southern continents and raises the question why only northern hemisphere T.Rexs evolved into giant predators, said the scientists.
"The existence of this hip bone shows that about 100 million years ago, in the Early Cretaceous period, small tyrannosaurs were found in other parts of the world," said Tom Rich, senior curator of Vertebrate Paleontology at Museum Victoria.
"This discovery changes our understanding of the evolution of this group of dinosaurs," Rich said in a statement.
(Reporting by Michael Perry; Editing by Sanjeev Miglani)
