Artist’s illustration of the traditional reptile Kostensuchus atrox
Gabriel Diaz Yanten, CC-BY 4.0
An historical crocodile relative that lived round 70 million years in the past was most likely such a formidable predator that it may have eaten medium-sized dinosaurs for breakfast.
“Its massive tooth had serrated edges like steak knives, which is a robust sign that this animal may tear by way of muscle and bone, most likely searching small-to-medium-sized dinosaurs or different massive prey,” says Diego Pol at the Nationwide Council for Scientific and Technical Analysis in Buenos Aires, Argentina.
Kostensuchus atrox, which in life would have been about 3.5 metres lengthy and weighed round 250 kilograms, was present in March 2020 in southern Patagonia. The fossil included a fantastically preserved cranium and elements of the predator’s skeleton.
Its genus title comes from the Patagonian wind often called the kosten and the Egyptian crocodile-headed god often called Souchos, with atrox that means fierce or harsh in Greek.
It lived on the finish of the Cretaceous and is from a bunch of crocodile kin often called the peirosaurid crocodyliforms, which didn’t survive the extinction occasion 66 million years in the past that additionally worn out most dinosaurs.
In contrast to trendy crocodiles, which have lengthy, flat snouts, Kostensuchus had a excessive, vast and very sturdy cranium constructed for sheer energy, says Pol. Its limbs had been extra elongated than these of recent crocodiles, suggesting that it was able to extra agile motion on land.
“Their physique proportions and cranium form recommend they may transfer higher on land and will have hunted on land too,” he says. “The cranium of Kostensuchus is far broader and extra sturdy than that of any dwelling crocodile.”

The fossilised cranium of Kostensuchus atrox
José Brusco, CC-BY 4.0
One other indicator that Kostensuchus was extra tailored for a life on land than trendy crocodiles is that its nostrils had been situated on the entrance of the snout, not on prime of the cranium, which implies it wouldn’t have been in a position to breathe and preserve most of its physique submerged on the identical time.
It had greater than 50 sharp, serrated tooth, some over 5 centimetres lengthy. Pol says these tooth weren’t only for gripping, but in addition for slicing by way of muscle.
“The again finish of its decrease jaw suggests it had large jaw-closing muscle tissue and one of the crucial highly effective bites of its ecosystem,” he says. “These traits helped us to put it as a prime predator, coexisting with massive meat-eating dinosaurs.”
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