New species of ancient crocodile nicknamed Shieldcroc

Researchers have identified a new species of prehistoric crocodile. The extinct creature, nicknamed “Shieldcroc” due to a thick-skinned shield on its head, is an ancestor of today’s crocodiles. 

Shieldcroc is the newest discovery of crocodile species dating to the Late Cretaceous period, approximately 95 million years ago. 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,” according to Casey Holliday, co-researcher and assistant professor of anatomy in the University of Missouri School of Medicine.

Researchers analyzed a portion of a fossilized crocodile skull to identify a new species, Shieldcroc. Analyzing scarring and ridges on the skull, he identified a thick-skinned “shield” on top of the skull. 

Holliday identified Shieldcroc by studying a fossilized partial skull specimen, which was discovered in Morocco and held by the Royal Ontario Museum of Toronto for several years before Holliday analyzed it. By analyzing blood vessel scarring on the bone, Holliday determined that the crocodile would have had a structure on top of its head, resembling a shield. The dents and bumps on the bone indicate veins delivered blood to a circular mound of skin, something never before seen in a crocodile. He said the shield was likely used as a display structure to attract mates and intimidate enemies and possibly as a thermo-regulator to control the temperature of the animal’s head.

Holliday compared Shieldcroc’s skull to those of other crocodilians. By comparing slopes of various bones, he found that the new species had a flatter skull than other known species. With this information, he believes it is unlikely that Shieldcroc wrestled dinosaurs on or near the shoreline. Instead, Holliday said the fossil indicates that Shieldcroc had thin jaws, likely used to catch fish.

Researcher and co-author Nick Gardner said:

    We believe Shieldcroc may have used its long face as a fish trap. 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.

In addition, Holliday analyzed Shieldcroc’s skull and brain to estimate the overall size of the reptile. He said scientists often use head size of an animal to estimate its total length. Using several parameters, Holliday and Gardner estimate that this specimen had a five foot long head and was 30 feet long.

Although Shieldcroc lived more than 90 million years ago, Holliday said scientists can use information about the animal to gain a better understanding of today’s crocodiles.

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