Mason Inman - science journalist

22 August 2007, for New Scientist

Humans are fortunate not to have lived alongside Tyrannosaurus rex.

The most sophisticated computer analysis of the gait of several two-legged dinosaurs suggests that even the lumbering T. rex could have kept up with an Olympic sprinter. Smaller dinosaurs, like the Velociraptor, could have outpaced the fastest humans with considerable ease.

Working out exactly how bipedal dinosaurs walked and ran is a vexing problem, since there are no living species with the exactly the same sort of build.

The closest living relatives of such dinosaurs are emus, ostriches, and chickens, which researchers already study in an effort to draw comparisons. However, previous estimates of dinosaurs' running speeds based on such comparisons have tended to vary wildly.

For example, a well-regarded study published in 2002, which compared the T. rex to chicken, suggested that this dinosaurs had just enough leg muscle to lumber along at about half the running speed of a person (see T. rex caught by speed limit).

Six-tonne chicken

William Sellers at the University of Manchester, UK, argues that this type of comparison can be misleading. "Such calculations can accurately predict the top speed of a six-tonne chicken, but dinosaurs are not built like chickens, nor do they run like them," he says.

Instead, Sellers and colleague Phillip Manning used an approach they dub "evolutionary robotics" to generate new estimates of the top speed of several two-legged dinosaurs. They built computer models featuring the leg bones, muscles, and skeletal structures of five groups of dinosaur: Tyrannosaurus, Velociraptor, Allosaurus (which looks like a miniature Tyrannosaurus), the slightly smaller Dilophosaurus, and the chicken-sized Compsognathus....

Read the rest of the article, on New Scientist's website.

Here's a video of the racing bipeds, courtesy of William Sellers: