Old Croc, New Tale

With their long snouts, sharp teeth, and strong tails, crocodiles are easy to recognize – and stay away from! Their appearance is common to the 23 species of living alligators and crocodiles, and to many extinct reptiles as well. People have long believed that crocodiles are themselves “living fossils”, having changed very little over millions of years.

Dr. Robert Hill with a cast of Simosuchus clarki

There is mounting evidence, however, that crocodiles were once an extremely diverse group, including members that were large, small, long-nosed, short-nosed, predators, and even vegetarians. Dr. Robert Hill of the College of Osteopathic Medicine’s Department of Anatomy recently worked with an international team of scientists to describe the anatomy of Simosuchus clarki, a bizarre crocodile that lived at the end of the “Age of Dinosaurs” (about 66 million years ago) on the island of Madagascar.


The fossils of Simosuchus are relatively complete, and very well preserved – a rare finding for paleontologists. Dr. David Krause of Stony Brook University, who led the study, believed that the beautiful and scientifically valuable specimens deserved a book-length monograph to describe them. “It just seemed unconscionable to not document such fantastic fossils of such a unique animal.” The monograph was published as a special Memoir of the Society of Vertebrate Paleontology, the premier professional organization for paleontologists.

The Simosuchus was three feet long, pudgy, with a blunt snout and the shortest tail of any known crocodyliform. View a video to learn more.

A separate chapter is devoted to each major part of the animal – skull, backbone, limbs, and armor. The volume is densely illustrated, with high-quality photographs, drawings, and even CT-scans depicting the intricate anatomy of Simosuchus. “The high-resolution CT scans in particular have allowed us to describe the skull in exceptional detail, including even the pathways of the tiniest nerves and blood vessels,” said Dr. Nathan Kley, also of Stony Brook University and one of the senior editors of the volume.

But while it is easy to lose oneself in the details of these incredible fossils, one of the most amazing features is the overall shape of the animal. Three feet long, pudgy, with a blunt snout and the shortest tail of any known crocodyliform, Simosuchus was not equipped to snatch unsuspecting animal prey from the water’s edge as many modern crocodiles do. Instead, its short jaw and weak, leaf-shaped teeth show that it probably munched on a diet of plants. While the idea of a gentle, vegetarian crocodile is unusual to us today, the new publication makes it easy to imagine Simosuchus ambling through its semi-arid grassland habitat, pausing to nip at plants and crouching low to hide from predators like the meat-eating dinosaur Majungasaurus.

As strange as Simosuchus was, the incredible completeness and preservation of its fossils, coupled with an equally impressive scientific investigation, have yielded one of the most comprehensive volumes of crocodile anatomy and evolution ever to be published.

Simosuchus has really shattered the crocodile mold, and set a surprising new standard for what constitutes a crocodile,” said Dr. Hill. “It reminds us that there is still a great deal left to learn about life in the ‘Age of Dinosaurs’, and that even the most convincing scientific hypotheses can still be overturned with new discoveries.”

View the publication here

Learn more about the Society of Vertebrate Paleontology at http://www.vertpaleo.org

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