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New Australian dinosaur fossil shows that tyrannosaurs’ range was global

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southern hemisphere first tyrannosaur rex globalTyrannosaur bones are relatively familiar finds on the northern continents of the globe, cropping up everywhere from modern-day Colorado to China. But until now, they appeared to be oddly missing from the southern half of the globe. The discovery of a distinctively tyrannosaur-like hipbone in Victoria, Australia, however, might change the way scientists think about the distribution—and evolution—of this infamous group of dinosaurs.

"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," Paul Barrett, of the Department of Paleontology at the Natural History Museum in London and a coauthor of the new report, said in a prepared statement.

The hipbone fossil is 30 centimeters long. "The bone is unambiguously identifiable as a tyrannosaur because these dinosaurs have very distinctive hip bones," asserted lead study author Roger Benson, of the Department of Earth Sciences at the University of Cambridge, in a prepared statement.

Extrapolating from the size of the hipbone, the researchers estimate that the new tyrannosaur would have been about the size of a person, measuring some three meters long and weighing in at about 80 kilograms. The animal lived in the Early Cretaceous, when members of the family were still small compared to the towering, Late Cretaceous Tyrannosaurus rex.

This as-yet unnamed dinosaur lived about 110 million years ago—about 40 million years before its revered relative the T. rex. At this time, the southern continents (Australia, Africa, South America and Antarctica) were still connected to each other, providing the researchers with "hints at the possibilities that others remain to be discovered in Africa, South America and India," Barrett said. The fossil find was detailed online on March 25 in Science.

Why did this group of dinosaurs appear to be so small and scant in the southern hemisphere while some tyrannosaurs later on were massive, dominating predators in the northern hemisphere? "It is difficult to explain why different groups succeeded in the north and south if they originally existed in both places," Benson said. "We can only answer these questions with new discoveries."

Image of where the new tyrannosaur fossil was found, in a place known as Dinosaur Cove in Victoria, Australia during the period in which the animal lived, courtesy of Roger Benson/Cambridge

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  1. 1. jtdwyer 3:51 pm 03/25/2010

    Relying solely on map image and presuming that Australia’s position during the Early Cretaceous was near the South Pole, climate could have had some affect on the the population and/or fossil preservation. It’d have been interesting to read a little about those topics in the article, or does this indicate that paleontologists haven’t noticed them yet?

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  2. 2. jtdwyer 8:00 am 03/27/2010

    On better thought I retract my closing comment regarding paleontologists – I have heard somewhere about the dinosaurs living on what’s now Australia having adapted to the polar night with improved night vision, and colder weather and shorter growing season by being smaller. So why wasn’t this even mentioned in the article? The illustration providing geologic perspective may have been the most informative part of the article.

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  3. 3. SkwosH 11:16 pm 04/7/2010

    Well, there has been a species of allosaur found in Australia, becoming famous when it was seen in Walking with Dinosaurs.

    Just one thing about fossil preservation, Australia was not subject to the massive ice sheets of the latest ice age, and thus many rocks did not have the chance to be eroded as much as North American rocks did.

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