"We're stuck again!" Scientist Paul Sereno and his team said those words many times as they drove into a rugged part of Africa. Desert sand kept stopping their Land Rovers. It took 10 hours to go just 87 miles.

That long crawl ended at Gadoufaoua (ga doo FAH wah), a dry region in the country of Niger (KNEE zhair). To most eyes, the place looked empty. There was sand. There was wind. There was nothing else. Or so it seemed.

But Sereno saw much more. He saw a chance to find dinosaurs. Being a dino expert, Sereno knew that the region contains countless fossils, or remains, from ancient dinosaurs. Gadoufaoua is one of Africa's richest sources of dino fossils.

Sereno found some fossils there in 1997. He came back in 2000 to seek more. The team spent four months in the desert. Crew members woke at 6:00 each morning, then explored the sand dunes for about 12 hours. They worked even when the temperature hit 125°F.

And they found fossils. By the end of the expedition, or trip, Sereno and his team had collected 20 tons of bones. Most of those fossils came from dinosaurs, including dino types never seen before. Others came from turtles, fish, and crocodiles.

One crocodile-like animal was awesome. Scientists call it Sarcosuchus imperator (SAR koh sue kis   im PER uh tor), a name that means "flesh crocodile emperor." Sereno's team nicknamed it "SuperCroc."

WHAT MAKES THIS CROC SO SUPER?

In a word, size. The skull alone was six feet long! Sereno says it's "about the biggest I've ever seen."

Naturally, Sereno wondered how big SuperCroc was overall. There isn't a live SuperCroc around to measure, and the team found only part of its skeleton. So Sereno had to make an estimate, or smart guess. To do that, he looked at crocodiles that live today. He and other experts compared the animals' skull and body sizes.

Based on his research, Sereno concluded that an adult SuperCroc could grow to be 40 feet long! That's roughly the length of a school bus. And the giant beast probably weighed as much as 10 tons. That's heavier than an African elephant.

Those measurements make SuperCroc one of the largest crocodiles ever to walk the Earth. Today's biggest crocs grow to about 20 feet.

WHEN DID SUPERCROC LIVE?

Estimating a fossil's age is a challenge. Sereno and his team looked carefully at the group of fossils they had found. They compared the fossils to others—whose ages scientists know. Based on those comparisons, Sereno believes SuperCroc lived about 110 million years ago.

Gadoufaoua looked a bit different in those days. What is now a desert was a land of winding rivers. Plenty of trees grew along the banks. Huge fish swam the rivers, while various dinosaurs lived in the forests.

Five or more crocodile species, or types, lurked in the rivers. SuperCroc, Sereno says, was "the monster of them all."

WHAT DID SUPERCROC EAT?

"Anything it wanted," Sereno says. SuperCroc's narrow jaws held about 130 teeth. The teeth were short but incredibly strong. SuperCroc's mouth was "designed for grabbing prey—fish, turtles, and dinosaurs that strayed too close."

SuperCroc likely spent most of its life in the river. Water hid the creature's huge body. Only its eyes and nostrils poked above the surface.

After spotting a meal, the giant hunter moved quietly toward the animal. Then—wham! That huge mouth locked onto its prey. SuperCroc dragged the stunned creature into the water. There the animal drowned. Then it became food.

IS SUPERCROC'S NOSE SWOLLEN?

No, it's not. SuperCroc's long head is wider in front than in the middle. That shape is unique, or one of a kind. No other croc—living or extinct—has a snout quite like it.

At the front of SuperCroc's head is a big hole. That's where the nose would be. That empty space may have given the ancient predator a keen sense of smell. Or perhaps it helped SuperCroc make noise to communicate with other members of its species.

DID ANYTHING ATTACK SUPERCROC?

Dinosaurs surely fought back when SuperCroc grabbed them. But we don't know of any creatures that went after this huge reptile.

Just in case, though, SuperCroc wore serious armor. Huge plates of bone, called scutes (skoots), covered the animal's back. Hundreds of them lay just below the skin. A single scute from the back could be a foot long!

WHAT HAPPENED TO SUPERCROC?

The giant beast probably lived only a few million years. That raises a huge question: Why didn't SuperCroc survive?

Sereno suspects that SuperCrocs were fairly rare. After all, a monster that big needs plenty of room to make a living. Disease or disaster could have wiped out the species pretty quickly. But no one knows for sure what killed SuperCroc. That's a mystery for future scientists—maybe even you.

Text by Peter Winkler
This article appears on pages 4-8 of our March 2002 issue.

LINKS

SuperCroc's Home Page
Check out Paul Sereno's official site for this huge discovery.

SuperCroc at National Geographic
Check out our coverage of Sereno and his work.

Game: SuperCroc Brainteaser
Bite into some cold-blooded questions about this giant reptile.

World of the Crocodilians
Encounter SuperCroc's modern cousins via this interactive map.

Project Exploration
Paul Sereno invites students to join scientific expeditions.

National Geographic Explorers-in-Residence
Meet eight extraordinary people who live and work at the frontiers of science—from anthropology to zoology.