A remarkable fossil has surfaced in southern Argentina, revealing an extraordinary predator from the late Cretaceous—Kostensuchus atrox. Dating back roughly 70 million years, this formidable reptile stood out as one of the region’s apex hunters. Discovered within the Chorrillo Formation in southern Patagonia, the near-intact specimen features a beautifully preserved skull, powerful jaws, and a partial skeleton—a rare find among peirosaurid crocodyliforms.
Measuring about 3.5 meters (11.5 feet) in length and weighing an estimated 250 kg (around 550 lb), K. atrox was built for dominance. Its wide snout, massive jaw muscles, and knife-like, serrated teeth all point to a hypercarnivorous lifestyle—feeding almost exclusively on meat—and suggest that it likely preyed on medium-sized dinosaurs.
The species’ name is a blend of local heritage and myth: “Kosten” nods to the strong Patagonian wind known in Tehuelche culture, “suchus” references Souchos, the crocodile-headed Egyptian deity, and “atrox” is Latin for “fierce”.
As the second-largest predator identified in the Chorrillo Formation and the first crocodyliform documented from there, this specimen sheds invaluable light on the ecological hierarchy of late Cretaceous Patagonia. It suggests a dynamic world where crocodyliforms like K. atrox shared top predatory roles with dinosaurs, competing for resources and shaping the prehistoric ecosystem Live Science.
Moreover, this fossil represents one of the most complete and anatomically informative peirosaurids discovered to date, opening new windows into the evolutionary pathways of broad-snouted crocodyliforms.
