A new study published in the Journal of Herpetology reveals that hellbenders once lived alongside wooly mammoths, saber-toothed cats, and other awe-inspiring creatures that roamed North America about 500,000 years ago. The authors, Keila Bredehoeft and Blaine Schubert of East Tennessee State University, examined the fossilized remains of a hellbender-like creature. These fossils are not a new discovery; they were found in a cave near the Potomac River in Maryland nearly 40 years ago. But at the time, there were few skeletons of modern hellbenders for comparison. Initial analysis of fossilized bone from the animal’s jaw, shoulder, leg, and spine suggested that it didn’t quite look like a normal hellbender. The animal was therefore called Cryptobranchus guildayi, and was considered an ancestor of our modern hellbender, Cryptobranchus alleganiensis.

In their new study, Bredehoeft and Schubert challenge the longstanding view that guildayi and alleganiensis are separate species. It turns out that if you look at a larger number of hellbender skeletons, these ancient fossils aren’t so different after all. What does this mean for modern hellbenders? First, they’ve survived on Earth much longer than we originally thought. The fossils are estimated to be between 400,000 and 850,000 years old. Second, hellbenders used to occupy parts of North America where they are now extinct. In this case, the fossils reveal that hellbenders once roamed the Potomac – the same river that flows past our nation’s capitol. Where else did hellbenders roam? Could the species be even more than 850,000 years old? Only the discovery of more fossils can answer these questions. And as you might imagine, it’s not too often that small, squishy river critters become fossilized.