Science|T. Rex Ran on Its Tiptoes ‘Like an 8-Ton Chicken’

In recent years, scientists have given Tyrannosaurus rex a makeover. Some have suggested that the dinosaur’s toothy maw was covered by fleshy lips. Others have reconstructed the beast with a fluffy coat of feathers.

Even the dinosaur’s earthshaking footsteps are being re-examined. An analysis of fossilized tracks and Tyrannosaurus rex’s lower leg anatomy are prompting a reconstruction of the dinosaur’s gait. The findings, published on Wednesday in the journal Royal Society Open Science, reveal that the top of the dinosaur food chain walked on tippy toes, not unlike modern birds.

“This study shows that even the iconic T. rex was quite birdlike in the way that it walked,” said Steve Brusatte, a paleontologist at the University of Edinburgh who was not involved in the study. “It would have been something like an eight-ton chicken clucking about in the barnyard.”

Adrian Boeye, an undergraduate student at the College of the Atlantic in Maine who studies biomechanics, led the project. He was interested in how Tyrannosaurus rex, an animal capable of weighing more than 10 tons, was able to move through its environment and chase down prey.

According to Mr. Boeye, previous efforts to reconstruct T. rex movements often simplified the dinosaur’s feet. “The feet were treated as these rigid blocks,” he said, that would simply stomp on the ground heel-first.

That style of locomotion differs from T. rex’s living relatives. Terrestrial birds, which are also dinosaurs, hit the ground with the front of their feet first. And instead of trudging along, birds use short, quick strides (think of the blur-like steps of the Road Runner in Looney Tunes) to sprint, helping reduce contact with the ground and allowing them to smoothly transition from walking to running. Larger birds utilize these short strides to reach speeds far faster — a sprinting ostrich can hit 43 miles per hour — than other bipedal runners, like humans.