Newly discovered ‘hypercarnivore’ croc ancestor ‘fed on dinosaurs’

By Stephen Beech

A newly discovered “hypercarnivore” ancestor of today's crocodiles was over 11 feet long and fed on dinosaurs.

Kostensuchus atrox was a top predator with a "powerful jaw and big teeth" capable of devouring large prey, say scientists.

They were able to accurately describe the heavyweight big beast that weighed around 250 kilos (551 pounds) - the same as an adult grizzly bear - thanks to a "remarkably well-preserved" fossil find in Argentina.

Paleontologist Professor Fernando Novas said K. atrox lived just before the extinction of the dinosaurs, and likely fed on them.

He explained that the fossil was discovered in the Chorrillo Formation in southern Patagonia, which formed around 70 million years ago, during the Maastrichtian age at the very end of the Cretaceous period.

Novas says that, at the time, southern Patagonia was a "warm, seasonally humid" landscape of freshwater floodplains, home to creatures including dinosaurs, turtles, frogs, and various mammals.

Dinosaur expert Novas said: "The new fossil unearthed in this formation is largely intact, including a skull and jaws with visible details, as well as multiple bones from the body.

"This crocodile-like apex predator may have reached around 3.5 metres (11.5 feet) long and weighed around 250 kilos, with a wide, powerful jaw and big teeth capable of devouring large prey — likely including medium-sized dinosaurs."

The research team named the species Kostensuchus atrox, referring to the Patagonian wind known in the Tehuelche native language as the Kosten and the Egyptian crocodile-headed god known as Souchos, with atrox meaning “fierce” or “harsh”.

Novas, of the Bernardino Rivadavia Natural Sciences Museum in Buenos Aires, said: "K. atrox itself is not a dinosaur, but rather a peirosaurid crocodyliform, an extinct group of reptiles related to modern crocodiles and alligators."

The species, described in the journal PLOS One, is the second-largest predator known to scientists from the Maastrichtian Chorrillo Formation.

Researchers believe it was likely one of the top predators in the region.

Novas added: "K. atrox is also the first crocodyliform fossil found in the Chorrillo Formation, and one of the most intact peirosaurid crocodyliforms ever found."