Fossil Find: 'Godzilla' Crocodile Had Head Of A Dinosaur, Fins Like A Fish

At the southern tip of South America , they found fossils of an entirely new species of ancient crocodile – one whose massive jaws and jagged teeth would have made it the most fearsome predator in the sea.

Unlike the crocodiles we know today, Dakosaurus andiniensis lived entirely in the water, and had fins instead of legs. But that's not all that made it unusual. Two other features – its hefty size and T. rex-like snout – have earned it a unique place in history – and the nickname “Godzilla.”

Diego Pol, a postdoctoral researcher at the Mathematical Biosciences Institute and the Department of Biomedical Informatics at Ohio State University , determined that the oddly shaped fossil specimens found in Patagonia belong on the crocodile family tree.

“This species was very unusual, because other marine crocodiles that were around at the same time had very delicate features – long, skinny snouts and needle-like teeth for catching small fish and mollusks,” he said. “But this croc was just the opposite. It had a short snout, and large teeth with serrated edges. It was definitely a predator of large sea creatures.”

Paleontologists Zulma Gasparini and Luis Spalletti of the National University of La Plata in Argentina uncovered the crocodile's fossil bones in Patagonia ; Pol used sophisticated software to map the features of those bones and determine its lineage. Together, they describe the creature in the latest issue of the journal Science.

It measured 13 feet from nose to tail. Its jaws were a foot-and-a-half long, with interlocking serrated teeth up to four inches long.

There were many other sizes of marine crocodile species alive 135 million years ago, toward the end of the Jurassic, but all had long snouts and needle-like teeth. None were larger than D. andiniensis, and none were as robust.

Yet, Pol found that the gargantuan crocodile was more closely related to the smallest of its brethren than any of the larger species. The shape of the nostrils, eye sockets, and other areas of the skull combined with a telltale groove in its jaw to prove its lineage.

“This is the most remarkable change in the size and shape of the teeth and snout in the history of marine crocs,” Pol said.

The three fossil specimens were found in 1996 – one on farmland in the Mendoza province of Patagonia , and two in a rock formation in Neuquén province to the south. During the time that D. andiniensis was alive, the region was a deep tropical bay of the Pacific Ocean .

The researchers don't yet know what events triggered the relatively sudden emergence of the large crocodile, but the size and shape of the teeth indicate that it probably fed on other marine reptiles and large sea creatures in the bay instead of small fish.

The National Geographic Society funded this research, and will feature D. andiniensis in the December 2005 issue of National Geographic Magazine.