The Tyrannosaurus Rex was a slowpoke

At 20 feet tall with enormous legs, you’d think the Tyrannosaurus Rex was a speed demon.

But really, the king of lizards could probably only keep a pace of about 12.5 miles per hour, with occasional shorter bursts if it was really going after prey.

Certain anatomical clues, at first, led scientists to believe that the T-Rex ran fast.

Firstly, they have long legs, up to 10 feet long.

Fast animals on Earth, like horses or antelope, also have long legs.

T-Rexes also have a specialized foot bone structure called an arctometatarsal, where the middle metatarsal bones is pinched between the outer bones.

Other therapod dinosaurs have an arctometatarsal, as well. Paleontologists think this created a type of shock-absorbing structure for fast running.

Specific markers on a T-Rex’s femur and tail vertebrate suggest a large, strong caudofemoralis muscle, which connects the femur to the tail and helps lift the leg.

All of these anatomical features point to T-Rexes being fast-runners, but now scientists think otherwise.

T-Rexes are, first and foremost, enormous. They were some of the largest land animals ever, probably weighing about eight tons. At some point, the laws of physics just don’t allow an animal that large to move very fast.

For instance, even though an elephant’s legs are longer than a horse’s, a horse can easily outrun an elephant.

Although smaller, the velociraptor could run much faster, partly because it had to be able to outrun predators while it itself was out hunting.

Paleontologists think that T-Rexes conserved their energy while foraging, only speeding up when they needed to tire out prey.

Even though T-Rexes were huge, it still takes a lot of energy to bring down a triceratops.

[Read the full story on this new study.]