Running not an option for Tyrannosaurus rex

In good news for anyone coming face to face with a Tyrannosaurus rex, a new study indicates that humans could outrun the fearsome dinosaur. By combining two separate biomechanical computer simulations, scientists at the University of Manchester have concluded that running would have been out of the question, and even the giant meat eater's walking speed would have been limited due to its size and weight.

The Tyrannosaurus rex is one of a handful of dinosaurs whose name is instantly recognizable. One of the largest predators to ever walk the Earth, the huge bipedal reptile lived during the Upper Cretaceous Period roughly 65 million years ago and grew up to 12.3 m (40 ft) in length and 3.66 m (12 ft) tall at the hips, with a weight between 8.4 to 14 tonnes (9.3 tons to 15.4 tons). It also had a set of serrated teeth and a bite that could exert about 8,000 lbf (35,586 N).

But despite being the center of intense study for over a century, there are still many unanswered questions surrounding the T. rex. One of the most important is how fast could it move? Over the years, there have been many attempts to estimate how fast the dinosaur could get around, with some studies suggesting speeds of up to 45 mph (72 km/h). Since even a horse can only do around 30 mph (48 km/h), a running human wouldn't have stood much of a chance if T. rex was still alive today and capable of such speeds.

But to obtain a more accurate assessment of a T. rex's speed, a team of scientists led by Professor William Sellers of the University of Manchester's School of Earth and Environmental Sciences looked at the gait and biomechanics of the dinosaur using a new computer simulation model. The model was developed by combining two separate biomechanical techniques called MultiBody Dynamic Analysis (MBDA) and Skeletal Stress Analysis (SSA).

By creating a simplified model of the T. rex's skeleton and muscles, the team figured out not only how such a massive biped could run, but also the load stresses that moving that fast would put on the skeleton, especially the leg bones.

They found that though a young T. rex could move relatively fast, by the time it reached adulthood, the stresses placed on the legs would have been so great that anything faster than a walking pace would have caused the bones to buckle. Needless to say, this meant that running was out of the question and the researchers say it would have limited the dinosaur's top speed to around 27 km/h (17 mph).

According to Sellers, the findings have implications beyond a new trivia fact to annoy fans of Jurassic Park. It explains why no running T. rex footprints have been found and will help paleontologists figure out what the dinosaur hunted and how it caught its prey. In addition, the technique can also be used on other large two-legged dinosaurs, including Giganotosaurus, Mapusaurus, and Acrocanthosaurus.

"Tyrannosaurus rex is one of the largest bipedal animals to have ever evolved and walked the Earth," says Sellers. "So it represents a useful model for understanding the biomechanics of other similar animals. Therefore, these finding may well translate to other long-limbed giants so but this idea should be tested alongside experimental validation work on other bipedal species."

The research was published in PeerJ (PDF).

The video below shows one of the T. rex simulations.

Source: University of Manchester