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Eudibamus cursoris
Illustration by Diane Scott
Science

Speedy Little Old Fossil

Oldest known fossil of a two-footed, running creature

Seven years ago in a quarry in central Germany, scientists unearthed a slab of stone that has forced a re-evaluation of the evolutionary time scale of terrestrial locomotion. The stone, which was given to U of T paleontologist Robert Reisz for study, contained the perfectly preserved fossil of a speedy little reptile, less than a foot long, who rose up on its hind legs and raced around the earth at least 60 million years before the dinosaurs walked erect.

In existence 290 million years ago, it is the oldest known fossil of a two-footed, running creature. “There are only a couple of times in evolutionary history when animals have gone from a sprawled posture like that of a four-legged lizard to an upright posture when they tuck their limbs under the body,” says Reisz, a professor in the zoology department at U of T at Mississauga. “It happened once in dinosaurs and again with mammals. So to find an example of an animal that did this before dinosaurs or mammals is particularly exciting.” Reisz and his colleague Diane Scott found that Eudibamus cursoris, as they named it, had short upper limbs for swinging by its sides, long legs for a fast stride and an oversized tail that acted like a rudder when it ran.

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