T-Rex Was Both Scary and Swift

Aug. 22, 2007 — While Tyrannosaurus rex would not have been able to chase down speeding vehicles, as "Jurassic Park" suggested, the 43-foot-long, 6-ton dino could comfortably reach a running speed of 18 miles per hour, according to new research in this week's Proceedings of the Royal Society B.

Co-author Phil Manning told Discovery News that this speed was "conservative," and indicated future research by his team would show how the toothsome predator probably could run even faster "if pushed to the limit."

The current study, he claimed, is the world's most accurate analysis yet of dinosaur running speeds.

"We are not scaling a modern species to behave like a dinosaur (as other research has done), but we are actually bringing animals back to life using science," said Manning, a paleontologist at the University of Manchester in northwest England.

Manning explained that he and his colleagues used powerful computing involving 256 processors and specially designed software to make the calculations for T. rex and other animals.

Watch an exciting foot race among T.Rex, several other dinos and a human. With race commentary.
Get more Discovery News video here.

The researchers began by plugging in skeletal, musculature, weight and other data for three living animals: humans, emus and ostriches. Since maximum running speeds were already known for these species, the entries tested the computer's accuracy.

The computer precisely determined that the average, fit male human's top speed is 17.7 miles per hour, emus run at 29.8 mph and ostriches can zip by both at an amazing 34.5 mph, making ostriches the fastest living animals on two legs.

Next, the scientists plugged in similar data for five bipedal meat-eating dinosaurs. These included a 6.6-pound Compsognathus, a 44-pound Velociraptor, a 948-pound Dilophosaurus, a 3,086.5-pound Allosaurus and a T. rex that weighed over 13,227 pounds.

If these dinosaurs raced, the world's smallest known dino — Compsognathus  — would have won, since it could comfortably reach speeds of 39.8 miles per hour. At around 3 feet long, Compsognathus was about the size of a modern turkey.

Manning said there appears to be a "power-to-weight ratio," with smaller species tending to move faster than larger ones. But he was quick to add that large animals, both living and extinct, can and have developed adaptations to improve their speed.

He pointed out that "huge giraffes" can run at nearly 25 miles per hour "on spindly legs," while "large dinosaurs would have possessed impressive muscle groups" and the ability to boost energy stores, such as lactic acid, which would have powered their bird-like, hollow bones.

Daniel Brinkman, a dinosaur expert with the Division of Vertebrate Paleontology at the Peabody Museum of Natural History at Yale University, told Discovery News that the new data confirms an earlier study by paleontologist John Hutchinson. Hutchinson's work concluded T. rex had a running speed that ranged between 10 and 25 miles per hour.

"For a big carnivore, that is surprisingly fast," Brinkman said.

He added that yet another team of scientists, led by paleontologist James Farlow, previously looked at what would happen if large dinosaurs like T. rex ran at around 40 mph, and then tripped.

"That research found the energy involved would have killed them if they tripped," Brinkman said. "At between 10 and 25 mph, T. rex would still probably have gotten hurt, but tripping would not have resulted in death."

USGS: How Fast Could Dinosaurs Walk or Run?

University of Manchester's Phil Manning

Peabody Museum of Natural History

American Museum of Natural History: Walk Don't Run