'Punk-size' T-rex discovered

This illustration shows a Raptorex (R), which is considered to be a tiny version of the Tyrannosaurus-rex (L). Photo / AP, Science, Todd Marshall

WASHINGTON - An early, smaller version of a Tyrannosaurus rex has been discovered. About 125 million years ago a tiny version of a T-rex roamed what is now north-eastern China.

Described by paleontologist Paul Sereno as "punk size," this early predator stood around 2.7 metres tall. The T-rex that evolved millions of years later was as much as 100 times larger.

The newly described remains were found by fossil hunters in northern China, smuggled out of that country and offered for sale to collector Henry Kriegstein, for whom the animal is now named, Sereno said.

The remains will be returned to China.

Described for the first time in Thursday's ScienceExpress, the online edition of the journal Science, the new dinosaur has been named 'Raptorex kriegsteini'.

"It really is the blueprint for the later (T-rex) dinosaurs," Sereno said, "it was a blueprint that was scalable."

Sereno from the University of Chicago and a National Geographic explorer in residence, reports that Raptorex has all the hallmarks of a T-rex, including a large head, tiny arms and lanky feet, just in a smaller size.

Raptorex would have weighed only about 68 kilograms, said Sereno.

"What we're looking at is a blueprint for a fast-running set of jaws," Sereno said at a briefing arranged by the American Association for the Advancement of Science.

The fossil was encased in a single block of stone, Sereno said. That stone allowed the researchers to trace the find to its original location.

The way the bones were fused indicates the animal died at the age of five or six, which is considered near the age of an adult.

It would have matured at eight or 10 and been old by 20, added Stephen Brusatte of the American Museum of Natural History.

The find also shows that features such as the animal's tiny arms did not evolve as T-rex grew larger but were present in the much earlier forms, Brusatte said.

"Much of what we thought we knew about T-rex turns out to be simplistic or out-and-out wrong," Brusatte said.

Sereno said Raptorex was a predator. Some scientists debate whether the T-rex was a predator or scavenger.

Dinosaur expert John R. Horner of the Museum of the Rockies at Montana State University called the report interesting but added that the drawing in the paper showed some differences from a T-rex in addition to being smaller.

However, he added that he didn't see anything that would disprove the theory that Raptorex was an ancestor of T-rex.

The T-rex dominated much of the planet from about 90 million years ago until the great extinction 65 million years ago.

- AP