Ferocious Tyrannosaurus rex was likely stuck in slow lane

Newsday

The scariest of the dinosaurs, Tyrannosaurus rex, was probably a slowpoke, scientists said Wednesday.

A new study of the beast’s proportions indicates that ferocious T. rex would have gone hungry if it needed to catch fast prey. Basically, the fearsome, 13,000-pound critter didn’t have enough muscles to get going fast.

"It is doubtful that Tyrannosaurus and other huge dinosaurs were capable runners, or could reach high speeds," John Hutchinson and Mariano Garcia, at the University of California, Berkeley, reported in today’s issue of the journal Nature.

Based on their own bio-mechanical studies of alligators and chickens, the two biologists said that "in order to run quickly, an adult Tyrannosaurus would have needed an unreasonably large mass of extensor muscle."

Fossilized footprints show that smaller dinosaurs ran like the wind, but no footprints left by T. rex and many of the other big varieties have yet been found. In other words, no data.

Now, a careful study of T. rex bones, its probable weight and its means of locomotion all point to the giant meat-eater being slow at 10 mph, not fast.

"Our calculations suggest that even a walking tyrannosaur required activation of a large fraction of its extensor muscle volume, at considerable metabolic expense," Hutchinson and Garcia explained. Meaning: Tyrannosaurs simply didn’t have the muscle power needed for high speed.

A specialist in animal locomotion, Andrew Biewener, at Harvard University, said the new results "show that even if the creature used all its hind-limb muscle mass, it could not have generated the forces necessary for running." Analysis showed that if a chicken grew as large as T. rex, "it would need muscles in each leg equivalent to 99 percent of its body mass — which is obviously impossible."

Biewener said the new data also suggest T. rex "would have had little success chasing smaller, more fleet-footed prey; it may even have fed on carrion. But I suspect it could have moved fast enough to attack other large dinosaurs whose locomotive ability was also limited."

This speed analysis applies to all very large dinosaurs, the two California researchers said, which means T. rex probably didn’t have to run very fast to catch equally lethargic prey, such as Triceratops.