Paleontologists have discovered a new species of prehistoric crocodile, named *Kostensuchus atrox*, in Argentina's Santa Cruz province. The find, announced in August 2025, provides significant insights into the fauna of Patagonia approximately 70 million years ago during the Late Cretaceous period.
The fossilized remains were found in the Chorrillo Formation near El Calafate. *Kostensuchus atrox* was a formidable predator, estimated to be around 3.5 meters (11.5 feet) in length and weighing approximately 250 kilograms (550 pounds). Its name reflects its fierce nature and Patagonian origins.
This discovery is notable as it is the first crocodyliform fossil found within the Chorrillo Formation. The well-preserved skull and jaws offer unprecedented details about the anatomy of broad-snouted peirosaurids, an extinct group of crocodylomorphs. Researchers believe *K. atrox* was a hypercarnivore, with powerful jaws and sharp, serrated teeth adapted for subduing large prey, potentially including medium-sized dinosaurs.
Evidence suggests *Kostensuchus atrox* was largely a terrestrial carnivore, inhabiting the warm, seasonally humid landscape of freshwater floodplains. It shared its ecosystem with dinosaurs such as *Maip macrothorax*, *Nullotitan glaciaris*, and *Isasicursor santacrucensis*. The presence of *K. atrox* highlights the complex predatory dynamics of Late Cretaceous Patagonia, indicating that crocodyliforms were significant apex predators, competing with theropod dinosaurs.
The finding expands the known geographic range of peirosaurids, suggesting their presence in temperate environments beyond Brazil and northern Patagonia. The Chorrillo Formation is a crucial site for understanding the fauna of southern Patagonia just before the Cretaceous-Paleogene extinction event, offering a vivid picture of a rich and dynamic ecosystem.