Ancient Crocodile Could Have Chewed Like You Do

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Chewing has always been thought of as a strictly mammalian ability. But during the reign of the dinosaurs a hundred million years ago, in the southern supercontinent of Gondwana, some crocodiles were likely doing something very close to that.

An ancient crocodile species has been discovered with molar teeth that fit together much like those of small carnivorous mammals. With lanky limbs, a lack of stiff armor on its back, and a nose ill-equipped for the water, it likely acted much more like a terrestrial cat than a fierce water predator.

“All of the things we’re finding really paint a picture of an animal that was active, agile, living up on land, moving around,” said anatomist Patrick O’Conner of Ohio University, lead author of the discovery August 4 in Nature. “When we look at the teeth compared to animals alive today, some of the closest comparisons are mammalian carnivores specialized for processing meat.”

Based on what scientists know about what was alive around that time, and the size of the new crocodile’s mouth, O’Conner says we can guess that it probably ate small reptiles and mammals and insects. Its molar-like teeth fit together, which would have allowed it to at least partially mash up the food before swallowing it, making it the only known non-mammal that may have been able to chew.


The mammal-like croc, named Pakasuchus kapilimai – which comes from paka, Swahili for cat, and souchos, Greek for crocodile –- is part of an extinct group of crocodiles called notosuchians. They were fairly small, with skulls just 2 to 6 inches long, thin limbs and forward facing noses. Notosuchians fossils have been found across the southern hemisphere once part of Gondwana.

“These really bizarre southern hemisphere small crocodiles really do approach what small mammals do,” paleontologist Gregory Buckley from Roosevelt University said. “And this finding really does raise the bar on what crocodiles did.”

All crocodiles today spend most of their time in water and have conical teeth that only allow them to slice and swallow. But notosuchian fossils suggest crocodiles were more diverse and prevalent on the landscape in Gondwana than mammals.

“If we take the fossil record at face value, we know a fair bit about the dinosaurs, the reptiles and the fishes that lived in the southern hemisphere around that time,” O’Conner said. “The mammals, by contrast, are not that well represented.”

By contrast, mammals in the northern hemisphere were rapidly diversifying and becoming the ancestors of all mammals alive today. One explanation for the diversity of crocodiles in Gondwana is they were filling niches that were being filled by mammals in the north, O’Conner says.

Most of this diversity was lost at the end of the Cretaceous Period 65 million years ago, around the same time as the mass extinction of the dinosaurs.

“It’s really hard to say exactly when or why the diverse crocodile forms died out,” Buckley said. “But it’s not so great of a stretch to think that whatever it was that so greatly impacted life at the end of the Cretaceous also had an effect on the crocodiles.”

Seven specimens of the chewing crocs have been found so far, all in different locations in Tanzania. Only two of the seven are fully described in the new study, one of which is a nearly complete skeleton.

In order to examine the teeth and skull of the complete fossil, which was encased in hard, red sandstone, the team of scientists used medical scanning technology called X-ray computed tomography to create a 3D computer illustration, shown in the video below. The illustration allowed the scientists to examine how the teeth fit together and how the creature might have chewed.



Read More Ancient Crocodile Could Have Chewed Like You Do | Wired Science | Wired.com

There's a video included in each of the articles a 3D model of how the teeth fit together.

Other article here: BBC News - Ancient 'cat-like' crocodile had bite like a mammal