Until recently, it was thought the dinosaur T-rex lived only in North America and Asia. Scientists have discovered a hip bone belonging to an ancestor of T-rex in Australia. The new species would have been about one-third to one-quarter the size of T-rex. The bone came from a dinosaur that lived earlier in the Cretaceous period than the T-rex.
This amazing discovery leads scientists to believe that the Tyrannosaurs may have lived all over the world including Antarctica. One of the reasons they are so widely distributed is that they evolved during the Late Triassic Period (beginning about 230 million years ago) when the continents we recognize today were still connected to each other.
The fossil of the oldest known tyrannosaur, an ancestor (named Guanlong wucaii) of Tyrannosaurs rex was found in China in 2006. The diminutive dinosaur, which lived 160 million years ago, measured about the height of 1 meter, estimated weight of 75 kg, and had a bizarre combination of features, including a large, fragile crest on its head that would have attracted mates but made it vulnerable in a fight. T-rex which came along 90 million years later was, stood about 13 meters long, weighed roughly 6 tons with powerful jaw and sharp serrated teeth. T-rex lived about 66-68 million years ago and was the most fearsome meat-eating dinosaurs to ever roam the Earth.
The first tyrannosaurs appeared about 170 million years ago and it was about the size of a human. The bones found in Uzbekistan where it lived about 90 million years ago were similar in size to a horse as opposed to the elephant-sized T-rex. But it had already developed the large brain and keen hearing needed to track and devour prey. Only after these ancestral tyrannosaurs evolved their clever brains and sharp senses did they grow into the colossal size of T-rex. (Floro Mercene)