New Prehistoric Crocodile Species Discovered
February 1, 2012

New Prehistoric Crocodile Species Discovered

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Researchers have discovered a new species of a 95 million year old prehistoric crocodile.

The "Shieldcroc" was part of the Mesozoic Era, which some scientists are starting to call the "Age of the Crocs," University of Missouri researcher Casey Holliday said.

"Aegisuchus witmeri or 'Shieldcroc' is the earliest ancestor of our modern crocodiles to be found in Africa," Holliday, co-researcher and assistant professor of anatomy in the MU School of Medicine, said in a press release. "Along with other discoveries, we are finding that crocodile ancestors are far more diverse than scientists previously realized."

The creature got its name due to a thick-skinned shield on its head, likely used as a display structure to attract mates and intimidate enemies.  Holliday said it also could have been used as a thermo-regulator to control the temperature on the animal's head.

The team found when comparing Shieldcroc's skull to other crocodilians that it had a flatter side than other known species.

Holliday said he believes the fossil indicates that Shieldcroc had thin jaws, which were likely used to help catch fish.

"We believe Shieldcroc may have used its long face as a fish trap," co-author Nick Gardner, an undergraduate researcher at Marshall University, said in a press release. "It is possible that it lay in wait until an unsuspecting fish swam in front of it. Then, if it was close enough, Shieldcroc simply opened its mouth and ate the fish without a struggle, eliminating the need for strong jaws."

Holliday analyzed Shieldcroc's skull and brain to determine the size of the reptile.  Scientists often use head size of an animal to estimate its total length.

The researchers believe Shieldcroc had a 5-foot long head and was 30 feet long altogether, which is about the length of a school bus.

"Scientists often estimate body size of crocodilians based on the size of the skull," Gardner said in the press release. "However, estimating the body size of Shieldcroc was difficult, due to the enormous size of the skull compared to other crocodilians. To make a size estimate, we compared several features of the bone to many different species."

Holliday said scientists are able to use information about the animal to help gain a better understanding of today's crocodiles, despite being extinct for 90 million years.

"Today's crocodiles live in deltas and estuaries, the environments put under the most stress from human activity," Holliday said. "By understanding how these animals' ancestors became extinct, we can gain insight into how to protect and preserve the ecosystems vital to modern crocodiles."

The discovery was published in the journal PLoS ONE this week.


Image Caption: MU assistant professor Casey Holliday nicknamed Aegisuchus witmeri “Shieldcroc” because of its thick skinned shield. Credit: Henry Tsai/University of Missouri


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