New Dinosaur Species Found

Sure it's pretty scary--beady eyes and all--but 125-million-year-old Raptorex kriegsteini (seen above in a new model) was no T. rex, at least in the size department. The newfound, 150-pound (70-kilogram) dinosaur, however, was nearly identical to its descendant, the 6-ton T. rex in every other way, a new study says. (Read full story.)

That Raptorex, via evolution, "scaled up, almost without change, a hundred times," resulting in T. rex some 40 million years later is an "evolutionarily staggering thing," said paleontologist Paul Sereno, lead author of the study, to be published in the journal Science tomorrow.

Newly discovered Raptorex gets underfoot of its nearly identical, though a hundred times heavier, descendant, T. rex in an artist's conception. The tiny T. rex ancestor is not known to have lived alongside its titanic ancestor.

The Raptorex find, announced September 17, 2009, runs counter to previous theories, which had said that stumpy arms were a relatively recent evolutionary development for T. rex.

Prior to Raptorex, said paleontologist Thomas Holtz of the University of Maryland, "we didn't know where and when in the history of the tyrannosaurs this arm-shortening occurred."

T. rex hypothetically could have swallowed a Raptorex head whole, skulls of both dinosaurs (pictured) suggest.

Raptorex has all the main characteristics of T. rex--big head, nipping teeth, stubby arms, fast legs--but packed into a 9-foot (3-meter) frame.

Paleontologist Paul Sereno of the University of Chicago adjusts the world's only known Raptorex skeleton, which was smuggled out of a Chinese fossil bed and later sold to U.S. collector Henry Kriegstein.

Kriegstein worked with Sereno to see that the T. rex ancestor, revealed in September 2009, was properly studied and allowed the skeleton to eventually be returned to China, where it eventually go on public display.

The Raptorex project can hopefully serve as a model for saving--and learning from--smuggled dinosaurs.

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