The most formidable dinosaur, Tyrannosaurus rex, could have chased down all but the fastest humans if they roamed the world today, British scientists claim.
The beast was capable of nearly 18mph, putting it fractionally quicker than a professional football player, but still lagging behind today's record-holding 100m sprinters who can exceed 20mph.
Researchers at Manchester University used powerful computers to model the skeletons and surrounding musculature of five meat-eating dinosaurs and three living species, including humans. Each virtual creature was then put through its paces to find the fastest running style and top speed. The computers used a technique called evolutionary robotics to work out the most likely gait of each creature, a process that took a week for each species. The results have produced what are believed to be the most accurate figures on dinosaurs' athletic abilities.
"Previously, people have assumed dinosaurs moved like animals alive today, but if you look at them, they aren't like anything still around today, so there's no reason to assume they'd move like them," said Bill Sellers, an expert in dinosaur biomechanics at the university.
"We use information about their bones and muscles and then ask the computer to work out the fastest way that creature could get from one place to another. If sometimes it wants to hop or skip, then it will," he added. Almost 100,000 simulations were performed to work out the most likely form of locomotion adopted by the creature. T rex had a habit of skipping as it sped up from a walking speed to a full run, the researchers found.
The scientists first tested the technique by modelling a 70kg human, an emu and an ostrich, the last two chosen for being quick two-legged beasts. The computer predicted the human to have a top speed of 17.7mph, the emu nearly 30mph and the ostrich 35mph. The five dinosaurs ranged in weight from the 3kg chicken-sized compsognathus, a 20kg velociraptor, a 430kg crested dilophosasurus, a 1½-tonne allosaurus and finally, a 6-tonne T rex.
With a top speed of 17.9mph, the T rex was the second slowest of all the creatures, but still outpaced the human. Among the other dinosaurs, the allosaurus could reach 21mph, the dilophosaurus 23.5mph, the velociraptor 24.2mph and the compsognathus able to beat any living two-legged creature on Earth with a top speed of nearly 40mph.
Scientists have long questioned how fast T rex could run, with some arguing that the beasts were so cumbersome, they were only capable of walking. The suggestion led some to suspect the dinosaur may not have been the fearsome hunter it is often portrayed as, but a scavenger feeding off speedier animals' leftovers.
"Our findings suggest T rex was far too quick to be a scavenger," said Dr Sellers, whose research is published in Proceedings of the Royal Society B.
Phil Manning, a palaeontologist at the university and coworker on the project, said future work would add tendons, ligaments and flesh for an even more accurate impression of how the animals will have looked as they moved around.
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