Washington — The first known creature to walk upright on two feet was a speedy, long-legged lizard that scurried onto the scene 80 million years before the dinosaur, a newly found fossil shows.
The lizard, less than a foot long and weighing under a pound, was a plant-eating reptile that researchers think used his speed and unique way of running to avoid the hungry meat-eaters that roamed the world 290 million years ago.
Walking upright on two feet is an example of "repeated evolution," where a physical advantage evolves in different species at different times in history, said Robert Reisz, a University of Toronto researcher and co-author of a study appearing today in the journal Science.
Bipedalism developed independently in dinosaurs, which passed it on to birds, and then later it developed in mammals, said Reisz.
"It was just such a good idea that it happened again and again," he said. "To find an example of an animal that did this before dinosaurs or mammals is particularly exciting."
Remains of the lizard were found in a German quarry. It took researchers more than two years to painstakingly remove the rock that encased the fragile, 10-inch-long fossil.
When the remains were analyzed, said Reisz, it was clear the lizard was a new species, now called Eudibamus cursoris, and that it was designed for swift, two-footed running.
The formation where the fossils were found has been age-dated at about 290 million years. The first dinosaur is thought to have appeared about 210 million years ago.
"This little animal was built for speed," said David Berman of the Carnegie Museum of Natural History and the first author of the study. "It was very, very fast."