Dogs do it. Cats do it. Pigs, cows, and hippos, too. But a new study suggests that the earliest known animal to have walked upright on all fours was a bizarre 'pre-reptile' that lived some 260 million years ago.
Dubbed Bunostegos akokanensis, the prehistoric plant-eater was the size of a cow, and walked like a cow. But its face was studded with big bony knobs.
Paleontologists first identified the B. akokanensis in 2003 after discovering a fossilized skull in the Sahara Desert of northern Niger. Now scientists have concluded that Bunostegos stood on all fours with its bulky body raised off the ground--unlike any other animal that roamed the supercontinent Pangea at the time.