Long before T-rex claimed the top dog spot among terrestrial predators, a vicious crocodile ancestor that walked on its hind legs was at the top of the food chain during the Triassic. The fossils of the Carnufex carolinensis, also known as the the “Carolina Butcher,” were discovered decades ago  in the Pekin Formation, a geological formation in North Carolina’s Chatham County. It was only recently that researchers reanalyzed the fossils and concluded they were dealing with an all new predator that roamed the Earth several million years before dinosaurs were even around.

Artist impression of the “Carolina Butcher,” Carnufex carolinensis. Credit: JORGE GONZALES

Lindsay Zanno, an assistant professor at North Carolina State University and the lead author of a paper describing the research, was among those who first analyzed the ancient fossils. She and her team dated the ancient croc as being 231 million years old. Using a high-resolution surface scanner, the team mapped the croc’s skull and created a 3-D model which revealed it was littered with dozens of blade-like teeth. In all likelihood, it used them to slice meat from the bones of the animals it killed or scavenged.

The model also showed that the Carolina Butcher stood at least 9 feet tall and most likely walked on two legs, judging from the forelimb to skull ratio (very similar to T. Rex). Sometime in the Late Triassic, however, the beasts went extinct following a massive wipe-out. In the end, its place was taken by large dinosaurs. But the smaller ancestors of crocodiles made it through the extinction, and eventually evolved in today’s crocs and alligators.

Reconstructed skull of Carnufex carolinensis.

The discovery is important since it fills an evolutionary gap. Even so, there are still unknowns further up the ladder, like who’s the common ancestor of the dinosaur line and the crocodile line?

A paper was published in the journal Scientific Reports.