Artist’s illustration of the traditional reptile Kostensuchus atrox
Gabriel Diaz Yanten, CC-BY 4.0
An historic crocodile relative that lived round 70 million years in the past was in all probability such a formidable predator that it may have eaten medium-sized dinosaurs for breakfast.
“Its giant tooth had serrated edges like steak knives, which is a powerful sign that this animal may tear via muscle and bone, in all probability searching small-to-medium-sized dinosaurs or different giant 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 superbly preserved cranium and elements of the predator’s skeleton.
Its genus title comes from the Patagonian wind generally known as the kosten and the Egyptian crocodile-headed god generally known as Souchos, with atrox that means fierce or harsh in Greek.
It lived on the finish of the Cretaceous and is from a gaggle of crocodile family members generally known as 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 fashionable crocodiles, which have lengthy, flat snouts, Kostensuchus had a excessive, huge and very sturdy cranium constructed for sheer energy, says Pol. Its limbs have 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 counsel 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 residing 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 fashionable crocodiles is that its nostrils have been positioned on the entrance of the snout, not on high of the cranium, which implies it wouldn’t have been capable of breathe and maintain most of its physique submerged on the similar time.
It had greater than 50 sharp, serrated tooth, some over 5 centimetres lengthy. Pol says these tooth weren’t only for gripping, but additionally for slicing via muscle.
“The again finish of its decrease jaw suggests it had large jaw-closing muscular tissues and one of the highly effective bites of its ecosystem,” he says. “These traits helped us to put it as a high predator, coexisting with giant meat-eating dinosaurs.”
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