SCIENCE / MEDICINE : Dinosaur Power Rating Hiked

The forelimbs of the ancient carnivorous dinosaur Tyrannosaurus rex appear to have been more powerful than previously thought, paleontologists reported last week at an evolutionary biology conference at the University of Maryland.

The new theory suggests that the small forelimbs of the dinosaur, once thought to be little more than weak vestigial extremities, could grasp prey weighing 400 pounds. Moreover, each of the forelimbs ended in two opposing claws that could tightly hold struggling prey, allowing the dinosaur to sink its razor-sharp teeth into the prey.

Matthew B. Smith of Montana State University and colleagues analyzed the most complete Tyrannosaurus skeleton ever excavated, discovered 18 months ago in eastern Montana. The bones include the first example of the dinosaur’s forelimb and claw. They studied muscle patterns left in the forelimb bones and correlated the thickness of the scars to the size that the muscles must have been present. Calculations revealed that the Tyrannosaurus could have lifted 400 pounds and each forelimb was as thick as a human thigh.