'Carolina butcher' walked on hind legs, terrorized early mammals in Late Triassic

NOAA

'Carolina butcher' walked on hind legs, terrorized early mammals in Late Triassic

When North Carolina was a wet, tropical swamp some 231 million years ago, the top of the food chain was occupied by a nearly 3-meter-tall crocodilian ancestor that walked on its hind legs and ate the relatives of early mammals, say paleontologists writing on 19 March in Scientific Reports. The researchers, from North Carolina State (NC State) University and the North Carolina Museum of Natural Sciences, both in Raleigh, say the newly analyzed fossil—parts of a skull, spine, and upper forelimb found in central North Carolina—represents one of the earliest examples of crocodylomorphs, a group of crocodilelike animals who ruled Earth in the Late Triassic. They vied with theropod dinosaurs for top predator slots and succeeded—for a time. By the end-Triassic extinction event, some 201.3 million years ago, only their smaller cousins remained, allowing dinosaurs to take over as top predators for the next 135 million years. But the discovery of Carnufex carolinensis, known as the “Carolina butcher,” was long in coming. For more than a decade, its bone fragments lay unidentified in the North Carolina Museum of Natural Sciences. After researchers dusted them off in 2014, high-resolution surface scanners and the more complete skulls of close relatives allowed them to create a three-dimensional model of the creature. The results were telling. “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,” says Lindsay Zanno, a professor at NC State and director of the museum’s paleontology and geology research laboratory. “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 Pangaea.”