Scientists have discovered a new species of a prehistoric crocodile based on a fossilized partial skull specimen that was found in Morocco and held by the Royal Ontario Museum for several years.
The finding, published Tuesday in journal PLoS-ONE (Public Library of Science), provides important clues about the evolution of crocodiles and how to protect them from extinction.
"Aegisuchus witmeri or Shieldcroc is the earliest ancestor of our modern crocodiles to be found in Africa," said co-author Casey Holliday, a professor of anatomy at the University of Missouri School of Medicine.
It is the newest discovery of crocodile species from the Late Cretaceous period, dating 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," Holliday said.
By analyzing blood vessel scarring on the skull bone, he 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.
He also analyzed the skull and brain to estimate the overall size of the reptile to be 30-feet long with a five- foot long head. Shieldcroc had a flatter skull than other known species and likely thin jaws that it used to catch fish rather than to wrestle dinosaurs on or near the shoreline.
"We believe Shieldcroc may have used its long face as a fish trap," said co-author Nick Gardner, an undergraduate researcher at Marshall University in West Virginia.
"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."
Insight gleaned about Shieldcroc can help scientists gain a better understanding of today's crocodiles, which is important as humans increasingly encroach on ecosystems, said Holliday.
"Today's crocodiles live in deltas and estuaries, the environments put under the most stress from human activity," he 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."