A Crocodile-Like Robot Helps Solve a 300-Million-Year Mystery

Nearly 300 million years ago, a curious creature called Orobates pabsti walked the land. Animals had just begun pulling themselves out of the water and exploring the big, dry world, and here was the plant-eating tetrapod Orobates, making its way on four legs. Paleontologists know it did so because one particularly well-preserved fossil has, well, four legs. And luckily enough, scientists also discovered fossilized footprints, or trackways, to match. The assumption has been that Orobates--a cousin of the amniote lineage, which today includes mammals and reptiles--and other early tetrapods hadn't yet evolved an "advanced" gait, instead dragging themselves along more like salamanders.