An ancestor of Tyrannosaurus rex (known as NMV P186069 for now) has been found at Dinosaur Cove in Victoria, Australia. A 110 million year old, 30 cm pubis bone was found and is distictively tyrannosaur because of its unique shape - rod shaped with two expanded ends, one of the ends flattened and the other boot shaped. The dinosaur would have been approximately 3 meters long and about 176 lbs with a large head and the small arms typical of a tyrannosaur. The large size of the T. rex is thought to have evolved later (about 40 million years later). This is the first ever evidence of tyrannosaur dinosaurs in the southern continents. The 110 million year old date of this fossil puts it somewhere in the middle of the continental breakup (from supercontinent to present day continental positions), suggesting that there may be more large predators yet to be discovered on the southern continents - the diversity of the tyrannosaur group isn't still fully understood.
Read more here: http://news.sciencemag.org/sciencenow/2010/03/scienceshot-t-rex-had-a-southern.html
and here: http://www.sciencedaily.com/releases/2010/03/100325143045.htm
(image from arizonaskiesmeteorites.com)