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Yale and University of Chicago researchers discover 40-foot crocodile fossil, possibly the largest known so far

October 31, 2001

The bones of a 40-foot crocodile that dined on dinosaurs and 12-foot-long fish have been discovered by researchers at Yale and at the University of Chicago in the Cretaceous rocks in Niger, Africa.

The crocodile weighed about 16,000 pounds and is called Sarcosuchus imperator. It was first described about 30 years ago by a French team, which found a partial skull. Since that initial discovery, virtually nothing had been done with the species until fieldwork by researchers in 1997 and 2000 produced three adult skulls measuring almost six feet long, three juvenile skulls and some associated postcranial or body skeletal elements.

The team consisted of Hans Larsson, now a postdoctoral fellow in Yale University's Department of Ecology and Evolutionary Biology, formerly of the University of Chicago; his graduate advisor Paul Sereno of the University of Chicago and others. Their results will be published online by the journal Science at the Science Express website on October 25 at 2 p.m. See

"The juvenile skulls are between three and four feet long, if you can call that juvenile," said Larsson. "Our calculations in the Science paper estimate the total adult body length to be between 39 and 42 feet long, probably the largest crocodile known so far."

The team sectioned the bony plates in the skin called scutes and found that the animals lived for about 42 years before reaching the large adult size. They estimate that the large adults lived to at least 50 years old. The Cretaceous rocks, where the crocodiles were found, are about 110 million years old and were deposited on the shores of an inland sea in a tropical environment in central Niger-now part of the Tenere Desert, which is a large section of the Sahara Desert.

Larsson said S. imperator is not a direct ancestor of modern crocodiles, but it is a close cousin. It most resembles the endangered Gharial crocodiles, which are found in India. The distinguishing feature of both the modern Gharial and the S. imperator is a rounded mass of flesh at the tip of the long snout that is used for vocalization. Gharial crocodiles are also the most primitive modern crocodiles. The largest modern crocodiles include the salt-water crocodile and Gharial, which have been recorded up to 24 feet in length.

The team's expeditions in Africa have also recovered numerous new dinosaur finds in Morocco and older rocks in Niger.
Other researchers on the study include Christian A. Sidor of the New York College of Osteopathic Medicine and Boubacar Gado of the Institut pour Recherche et Science Humaine, Niamey, Republic of Niger.

Yale University

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