Ancient crocodile fossil found in Chatham
Posted March 19, 2015
Raleigh, N.C. — Scientists at North Carolina State University and the North Carolina Museum of Natural Sciences have discovered an ancestor of crocodiles that likely was a dominant predator in what is now North America before the age of dinosaurs, according to a report published Thursday in the open access journal Scientific Reports.
Carnufex carolinensis, or the “Carolina Butcher,” was a 9-foot-long, land-dwelling crocodylomorph that walked on its hind legs and likely preyed upon smaller inhabitants of North Carolina ecosystems such as armored reptiles and early mammal relatives, said Lindsay Zanno, assistant research professor at N.C. State, director of the Paleontology and Geology lab at the museum and lead author of a paper describing the find.
"This guy was pretty big. I probably would have been the right size for lunch," N.C. State graduate student Susan Drymala said Thursday. "There’s plenty of scary things out there today, but nothing this big."
Paleontologists from the museum and N.C. State found the fossils in 2004 in a rock quarry in Chatham County. They date to the beginning of the Late Triassic Period, which was about 231 million years ago, when what is now North Carolina was a wet, warm equatorial region beginning to break apart from the super-continent Pangea.
"Originally, they were in a boulder about the size of a Volkswagen," museum curator Vincent Schneider said. "So, it took three to four days in the field to actually remove the specimens from the boulder because we had to cut them out with a rock saw."
Schneider brought the fossils back to the museum, where they remains a mystery for several years.
"We knew they were some kind of early Triassic vertebrate," he said.
Drymala, who was then studying Triassic animals, began investigating the bones, and she and Zanno were able to identify the fossils as parts of a skull, spine and upper forelimb.
"It’s a significant find. It’s not like a whole animal, but there was enoigh there to actually determine the relationships between it and other crocodilian-like animals,” Schneider said.
Because only pieces of the skull were found, Zanno, Drymala and other researchers had to scan the individual bones with a high-resolution surface scanner and use the more complete skulls of close relatives to fill in the missing pieces as they created a three-dimensional model of a Carnufex skull.
"It definitely was one of the biggest things for its time. Its skull was at least a foot and a half (long)," Drymala said.
"Fossils from this time period are extremely important to scientists because they record the earliest appearance of crocodylomorphs and theropod dinosaurs, two groups that first evolved in the Triassic period yet managed to survive to the present day in the form of crocodiles and birds," Zanno said in a statement. "The discovery of Carnufex, one of the world’s earliest and largest crocodylomorphs, adds new information to the push and pull of top terrestrial predators across Pangea."
Typical predators roaming Pangea included large-bodied rauisuchids and poposauroids, fearsome cousins of ancient crocodiles that went extinct in the Triassic Period, she said. They hunted alongside the earliest theropod dinosaurs in the Southern Hemisphere, but the discovery of Carnufex indicates that large-bodied crocodylomorphs, not dinosaurs, held some of the top predator niches in the Northern Hemisphere, she said.
"We knew that there were too many top performers on the proverbial stage in the Late Triassic," she said. "Yet, until we deciphered the story behind Carnufex, it wasn’t clear that early crocodile ancestors were among those vying for top predator roles prior to the reign of dinosaurs in North America."