CHICAGO, Sept. 18 (UPI) -- The discovery of a smaller precursor to Tyrannosaurus Rex has changed the way scientists view the evolution of T. Rex, paleontologists said.
Scientists now are re-thinking the orthodoxy that T. Rex's distinctive characteristics -- huge head, strong jaws and truncated forelimbs -- signified a necessarily gigantic dinosaur, The Washington Post reported Thursday.
T. Rex was 43 feet long and weighed around 13,000 pounds. But the newly discovered dinosaur, Raptorex kriegsteini -- which came along around 125 million years ago, about 35 million years before T. Rex. Raptorex -- was a mere 9 feet long and weighed 150 pounds, The New York Times reported.
"The thought was these signature Tyrannosaurus features evolved as a consequence of large body size," said Stephen L. Brusatte of the American Museum of National History, co-author of an article on the discovery in the journal Science.
Brusatte said the discovery "really throws a wrench into this observed pattern."
As dinosaurs evolved and their heads became larger, their limbs became shorter.
"A skeleton is a tradeoff," said Paul Sereno, a University of Chicago paleontologist who wrote the article with Brusatte. "This is an agile, fast-running animal. By adding a lot of weight at the top, something has to give way. What gave way was the forelimb."
The dinosaur fossil was discovered almost completely encased in rock in the early part of the decade in China, excavated illegally, and ultimately legitimately purchased by Henry Kriegstein, a Massachusetts ophthalmologist and amateur paleontologist.
In 2006, Kriegstein consulted with Sereno, who, realizing the fossil was a major scientific breakthrough, agreed to examine it on condition Kriegstein give it up to science.
Kriegstein agreed, provided the new dinosaur be named for his elderly Holocaust survivor parents.
"I wanted to find a way to let their name live on in immortality," he told the Chicago Tribune, and the surviving fossil seemed fitting: "My parents came close to not surviving. This name symbolically represents that they have survived despite great odds."
