Its discoverer calls it "Godzilla," a fearsome 13-foot seagoing crocodile with saw teeth, a fish tail and jaws capable of ripping apart almost any other creature it encountered in the ancient ocean off what is now South America.
"There were other large sea predators in the region, but no large sharks at this time," said Zulma Gasparini of Argentina's National University at La Plata, who announced the discovery of the creature's fossil remains yesterday. "These crocodiles were top predators."
Gasparini and co-researcher Diego Pol of Ohio State University described Dakosaurus andiniensis as a unique and sophisticated species of crocodile that lived 135 million years ago and whose bullet-shaped skull looks more like that of a land-dwelling carnivore than that of a sea creature:
"Dakosaurus probably fed on other large marine reptiles," Pol said in a telephone news conference sponsored by the National Geographic Society, which helped to fund the research. The team's findings appeared in Science Express, an online edition of the journal Science.
Gasparini said she first learned of the existence of D. andiniensis during a 1996 visit to a small museum in the central Argentine province of Mendoza. In a drawer she found "bone fragments that I recognized as crocodilian." Museum staff told her "local people found them and brought them in." She named the species but could find out nothing more about it.
Gasparini is one of the leading paleontologists working in the fossil beds of northwestern Patagonia's Neuquen Basin, a treasure trove of remains of prehistoric crocodiles and other marine reptiles.
The new specimens announced yesterday -- a lower jaw and a nearly complete skull with a lower jaw -- were found in the basin's Vaca Muerta Formation. Gasparini recognized them as belonging to D. andiniensis.
Pol said that before the new discovery, most prehistoric crocodiles had long, low snouts and lots of small sharp teeth -- like the crocodiles of today. "They were all thought to have been fast swimmers that fed on small prey -- especially fish," Pol said.
The new sea monster was no fish chaser. The jaw and snout were short, high and extremely powerful, Pol said. The jaws had relatively few teeth, but they were large and serrated on the edges -- saw teeth used for slashing and cutting, like those of land-based predatory dinosaurs.
Pol said the skull had enough similarities to crocodiles to rule out the possibility that it was a completely different animal. Instead, he added, it was an example of "convergent evolution." D. andiniensis's evolved its own snout because, like land-based predators of the time, it used it to grab other large animals and tear them apart.
"Everyone knows about the age of dinosaurs, and how they ruled the Earth, but during the same time [seagoing reptiles] occupied and even dominated the world's oceans," Pol said. Evidence found at Neuquen suggests that D. andiniensis survived and prospered until the extinction of the dinosaurs 65 million years ago, he added:
"The only lineage that survived is the one that became today's crocs."