Sunday, March 28, 2010

1st Southern Tyrannosaur

A Southern Tyrant Reptile. 2010. R. B. J. Benson, et al. Science 327: 1613

A 30 cm long pubis (above) found at Dinosaur Cove in Victoria, Australia has been identified as belonging to an ancestor of Tyrannosaurus rex. The find sheds new light on the evolutionary history of this group of dinosaurs. It also raises the crucial question of why it was only in the north that tyrannosaurs evolved into the giant predators like T. rex.

"Although we only have one bone, it shows that 110 million years ago small tyrannosaurs like ours might have been found worldwide. This find has major significance for our knowledge of how this group of dinosaurs evolved." says Dr Benson.

The bone would have come from an animal about 3m long and weighing around 80 kg, similar to a human, and would have had the large head and small arms that make tyrannosaurs so distinctive.

Compared with T. rex, which lived about 70 million years ago at the end of Cretaceous period, NMV P186069 lived earlier during the Cretaceous, around 110 million years ago.

While answering the question of whether or not tyrannosaurs lived in both the southern and northern hemispheres, the new find leaves another, deeper mystery: why did tyrannosaurs evolve into giant predators such as T. rex only in the northern hemisphere? link