Researchers from the University of Missouri have discovered a new species of prehistoric crocodile, nicknamed the Shieldcroc. The Shieldcroc is an ancestor of today's crocodiles, and provides researchers with insight into the evolution of crocodiles.
Casey Holliday, the lead researcher on the study, was able to identify the Shieldcroc by studying a fossilized skull specimen. The Shieldcroc skull was discovered in Morocco and was held by the Royal Ontario Museum of Toronto for several years before Holliday analyzed it. The study was published Tuesday in the online journal PLoS ONE.
By analyzing scarring on the skull, Holliday determined that the Shieldcroc would have had a large structure on the top of its head, resembling a shield. Veins in the skull, indicated by dents and bumps on the bone, show that blood was delivered to a circular mound of skin, something that has never been seen in crocodiles before. He said that the shield was most likely used to attract males and intimidate enemies, and may have been used to regulate the Shieldcroc's body temperature. Some crocs build small horns, but no croc has ever been found with a structure like that found on Shieldcroc, Holliday said.
The Shieldcroc was dated back to the Mesozoic Era, approximately 95 million years ago, which Holliday dubbed the Age of Crocs, due to the number of crocodiles that scientists have discovered from that era.
The Sheildcroc is different from other crocodiles in a variety of ways, such as the ornamentation on the skull and how some bones articulate with others. What cemented the fact that this was an entirely different species however was how flat the skull was - much flatter than any other species. The flatness also indicated that the Shieldcroc likely had thin jaws, used to catch fish.
We believe Shieldcroc may have used its long face as a fish trap, co-author Nick Gardner told the University of Missouri News. 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.
The researchers estimated the overall length of the Shieldcroc to be 30-feet long with a five-foot head. Scientists often estimate body size of crocodilians based on the size of the skull, Gardner said to University of Missouri News. 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 this discovery shifts the hypothesis of where crocodiles originated. Before, it was argued whether [crocodiles] originated in Europe or North America. Now Africa may be a possible origin for the group as well. It's no surprise to find these largely aquatic crocs on the other side of the Mediterranean---they seem to be able to disperse easily-but it's the first solid record.