Giant croc, unbelieviable!

Paleontologist Paul Sereno and his colleagues pieced together a portrait of the monster—which they've dubbed SuperCroc—based on fossils they've collected at Gadoufaoua in Niger, a remote site in the Sahara Desert where Tuareg nomads roam.

The fossils are from an extinct species that first came to light more than 30 years ago. French paleontologists reported several skulls and other parts of the creature and named it Sarcosuchus imperator, meaning "flesh crocodile emperor."

Much about the giant croc remained a mystery, however, until Sereno's team began excavating at Gadoufaoua in 1997. "People hadn't gone back with any expedition capacity since then, so not much else was collected," said team member Hans Larsson.

The 1997 dig had barely begun when the team discovered the fossilized jaws, each as long as some members of the team. The group had traveled to the site—one of the richest fossil beds in Africa—to search for dinosaurs. But it was immediately clear that the giant jawbones had not come from a dinosaur, Sereno said. 

Paleontologist Paul Sereno,a Nationall Geographic Society Explorer-in Residence,and the skull of Sarcosuchus imperator, nicknamed SuperCroc.The behemoth's skull is about six feet (1.8 meters) long.

The giant creature, which lived 110 million years ago, during the Middle Cretaceous, grew as long as 40 feet (12 meters) and weighed as much as eight metric tons (17,500 pounds).

Its jaws alone were nearly six feet (1.8 meters) long and its more than 100 teeth so powerful that the colossal creature
probably consumed small dinosaurs as well as fish, the researchers say. 

SuperCroc lived in Africa during the Middle Cretaceous period, when broad rivers stretched across lush plains.

Larsson said Sarcosuchus was not from the same branch of the reptile family tree that gave rise to modern crocodilians, which consist of about 23 species that include alligators, crocodiles, caimans, and gharials. "It's not a modern croc, but they share an early common ancestor," he said.

The oldest precursors of crocodiles may have spent more time on land, but Sarcosuchus was a river dweller that appeared after early crocodilians had already split into two separate land-based and marine groups.

Sereno said Sarcosuchus probably spent most of its time underwater, "living an ambush lifestyle." Like the gharial, a large long-nosed crocodilian in India, the ancient croc had eye sockets that tilted upward, which helped it conceal its huge body underwater while scanning the river's edge.

Another distinctive feature that Sarcosuchus had in common with the gharial was a round bony protrusion at the tip of its snout that housed a large bowl-shaped inflatable nasal cavity, called a bulla. The function of the bulla isn't clear, but the researchers think it may have heightened the croc's sense of smell or enabled it to emit striking calls. Larsson said gharials are known to use the muscles around the bulla to make different kinds of sounds, especially for mating.

Sereno said some people have an erroneous image of crocodiles "as dumb, clumsy, silent creatures." But crocodiles "are anything but clumsy, and they communicate extensively by calling, even roaring and splashing," he said. "It looks as if Sarcosuchus did some of that too."

The narrow jaws of an adult Sarcosuchus housed more than 100 teeth, which Larsson likened to "railroad spikes." While the giant croc shared the water with large fish, its hearty teeth—which included bone-crushing incisors—suggest that Sarcosuchus "didn't seem limited to eating fish," Larsson said. Other prey may have been small dinosaurs and other terrestrial animals, such as turtles.

Overlapping rows of scutes covered the crocodile's body from head to tail, forming a tough protective armor. The scutes, like trees, have annual growth rings. By counting these rings in the fossilized scutes, the researchers estimated the giant croc's full life span as 50 to 60 years.