Orobates

What it is

An animal about three feet long, and about as heavy as a house cat, that lived about 294 million years ago in what is now central Germany. It is not a reptile. It belongs to a family called the diadectids, plant-eaters that were close cousins of the ancestor reptiles and mammals share.

The footprints came first

For more than a century, quarry workers at the Bromacker quarry split its footprints out of the sandstone: five toes with rounded tips. The tracks were named in 1895. For decades nobody could say what made them, and the guesses ran all the way to a giant salamander.

Then the same quarry gave up complete skeletons, every bone in place, down to the toes. The animal was named Orobates in 2004. Scientists laid its toe bones against the prints, and the toes matched: in both, the outer toe of the foot is about four-fifths as long as the toe beside it. The skeletons and the tracks lie in different layers of rock, so the tracks belonged to its kind, not to one particular animal.

How it walked

Bones and prints cannot show you a walk. So in 2019 a team built a robot with its proportions and its balance, and a computer tested 512 ways it could have walked. The walks that passed held the body fairly high, off the ground, closer to a caiman than to a salamander. Walking like that was thought to have come later, with the first reptiles and the first relatives of mammals.