But even as the first Nothronychus was heading to press, a second one had been uncovered. Merle Graffam found a more complete skeleton in slightly older rocks of southern Utah. No one had expected to find a dinosaur in the rocks Graffam was searching. The sediment was from an ancient seaway that yielded plesiosaurs and other marine reptiles. But the anatomy didn’t lie. In 2009, Lindsay Zanno named the dinosaur as a second species of Nothronychus – N. graffami – that had been washed out to sea and buried far from shore.

The second skeleton provided paleontologists with a far more detailed view of Nothronychus than the first. But did the two bodies really belong to different species? University of Pennsylvania