Paleontologists Identified New Species of Ancient Crocodile

A team of paleontologists has identified a new species of prehistoric crocodile, nicknamed ‘Shieldcroc’ due to a thick-skinned shield on its head.

A portion of its fossilized skull was unearthed from the Cenomanian Kem Kem Formation of southeastern Morocco several years ago.

Life restoration of Aegisuchus witmeri (Henry P. Tsai / University of Missouri)

The study, published in the journal PLoS-One, suggests that the new species, called Aegisuchus witmeri, measured about 30 feet in length and had 5-foot-long flat skull with large jaw and craniocervical muscles.

“Scientists often estimate body size of crocodilians based on the size of the skull,” said Nick Gardner, a co-author on the study and an undergraduate researcher at Marshall University. “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.”

Aegisuchus witmeri or Shieldcroc is the earliest ancestor of our modern crocodiles to be found in Africa,” said Dr. Casey Holliday, co-researcher and assistant professor of anatomy in the University of Missouri’s School of Medicine. “Along with other discoveries, we are finding that crocodile ancestors are far more diverse than scientists previously realized.”

Shieldcroc lived in the Late Cretaceous period, about 95 million years ago.

A portion of Aegisuchus witmeri's fossilized skull (Casey Holliday et al)

“This period is part of the Mesozoic Era, which has been referred to as the ‘Age of the Dinosaurs,’ however, numerous recent discoveries have led to some scientists calling the era the ‘Age of the Crocs’,” Dr. Holliday said.

The paleontologists identified Shieldcroc by studying a specimen held by the Royal Ontario Museum of Toronto for few years before they analyzed it.

“We believe Shieldcroc may have used its long face as a fish trap,” Gardner said. “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.”

Aegisuchus witmeri is named in honor of Lawrence M. Witmer, in recognition of his mentorship and contributions to archosaur cranial anatomy that enabled the identification and interpretation of the species.

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