T.rex relative turns up Down Under

By Kylie Piper 26 March 2010
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Never before discovered in the Southern Hemisphere, a tyrannosaur hip bone has been found at Dinosaur Cove, Victoria.

A PRIMITIVE RELATIVE of the mighty tyrannosaurs has been found in Australia. Previously only known from the Northern Hemisphere, the discovery is evidence that these carnivorous dinosaurs were rulers of the outback 110 million years ago – some 40 million years before the time of T.rex itself.

The size of the bones suggests a dinosaur about one third the size of T.rex. The Aussie species would have been about three metres in length, weighing in at perhaps 80 kg, with a large head and small arms similar to its mighty cousin. The discovery is revealed today in the US journal Science.

Australia’s Tyrannosaurus

During this time in the Earth’s history Australia was still part of the great southern continent of Gondwana and was much further south than today. Victoria’s tyrannosaur and the other dinosaurs of the time would have been living through dark polar winters in the Antarctic Circle.

“The absence of tyrannosauroids from the southern continents was becoming more and more anomalous as representatives of other ‘northern’ dinosaur groups started to show up in the south,” says Paul Barrett, study co-author and palaeontologist from the Natural History Museum in London, England.

“This find shows that tyrannosauroids were able to reach these areas early in their evolutionary history and also hints at the possibility that others remain to be discovered in Africa, South America and India.”

The bones were discovered at Dinosaur Cove in Victoria in 1989 but sat in a drawer until 2009, when palaeontologist Tom Rich of Museum Victoria in Melbourne, took them to London for a second opinion. “I made a trip to the UK…last year and I took this case of bones with me,” Tom told Australian Geographic. “Everything else turned out to be ho-hum but that one turned out to hit the jackpot!”

T. rex ancestor

The description of the new species was made by palaeontologists from London and Cambridge, from just one bone – the pubis. These diagnostic bones make up part of the dinosaur’s hip and are almost identical to those from the tyrannosauroid families from the northern hemisphere, Tom says.

Roger Benson of the University of Cambridge, UK, says the distinctive hip bones are definitely from a T. rex ancestor: “Although we only have one bone, it shows that 110 million years ago small tyrannosaurs like ours might have been found worldwide.”

“It’s probably a small adult that we’re looking at rather than a juvenile, says Tom. “Simply because at that time elsewhere in the world there weren’t any big ones – they come later.”