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University of Missouri

Identifying Crocodiles

MU researcher identifies prehistoric crocodile species.

illustration of prehistoric crocodile

Illustration by Henry P. Tsai.

Ninety‐five million years ago, North Africa was a hot, misty delta green with vegetation and low‐hanging trees. Among its inhabitants were crocodiles up to 40 feet long — some running on land, some with flippers paddling in the water, others dining on carcasses, plants or gulping down giant fish. The region had at least eight species of crocodiles.

In February 2012, an MU paleontologist discovered yet another species from the Late Cretaceous period. Nicknamed “Shieldcroc,” the animal was perhaps 25 feet long with a pancake snout and, most remarkably, a glowing raised surface on its skull.

The fossils we’re finding from this period indicate that crocodiles we have today are really more boring than those living in the age of dinosaurs,” says Casey Holliday, co‐researcher and assistant professor of anatomy at the School of Medicine. “In fact, there was such amazing diversity then that it might be better to call the period the age of crocs.”

Rather than the typical skull dimples, Shieldcroc, aka Aegisuchus witmeri, has blood vessel scarring, suggesting that blood circulated in a rise, or shield, atop its head.

Holliday suspects Shieldcroc’s shield was used to signal intimidation or perhaps to regulate brain temperature.