It weighed 17,500 pounds (7,938 kilograms), was 40 feet (12.2 meters) long, and probably ate dinosaurs for dinner.
Sarcosuchus imperator, an ancient relative of modern alligators and crocodiles that roamed the Sahara Desert 110 million years ago, had jaws of steel that no prey—not even small dinosaurs—could pry open, according to researchers. Being trapped in the jaws of this monster—dubbed "SuperCroc" by paleontologists—would be equivalent to being trapped under the weight of a Mack Truck, explained Greg Erickson, a biologist at Florida State University.
Erickson and his colleagues extrapolated the bite force of SuperCroc from data they collected by provoking living alligators and crocodiles at a zoological park in Florida to chomp on a "bite bar." Basically a rod encased in leather, the instrument measures bite force strength in much the same way a bathroom scale measures weight.
In April 2002, Erickson and his colleagues took to the unbound lakes and rivers of central Florida to see if wild alligators bite with more force than those kept in captivity.
The original research—which was filmed for a National Geographic Special on SuperCroc that aired in December 2001 on the National Geographic Channel, and which will be repeated at 8 p.m. and 11 p.m. ET/PT, April 6, 2003 and 5 p.m. ET/PT April 12—was conducted at the St. Augustine Alligator Farm and Zoological Park in Florida.
There, Erickson and his colleagues Kent Vliet, a zoologist at the University of Florida in Gainesville, and Kristopher Lappin, a biologist at Northern Arizona University in Flagstaff, wrestled more than 60 crocodilians to shore long enough to induce them to chomp viciously on the seven-foot-long (two-meter-long) bite bar.
The bar has four piezoelectric sensors, shaped like washers, that are sandwiched between two steel plates. "When the animal bites the plates and squeezes them together, we get a reading," said Lappin. "The four sensors are wired together so that a bite anywhere on the plates will give an accurate reading of the force."
The trick is to get the crocodiles or alligators to bite the bar.
To do so, the researchers sling a rope around the creature's neck and pull it ashore, where Vliet jumps on the animal's back.
"I have to get onto the animal's back before we place the bite bar to try to prevent the animal from rolling when it does bite and possibly breaking our equipment," he said. Each bite bar costs up to U.S. $10,000, depending on size.
Once an animal is secured, Erickson and Lappin tap the snout, which induces the mouth to open so the researchers can insert the bite bar on the rear teeth. Alligators and crocodiles have nerves in their teeth, and when they feel the bar, they chomp down.
"It is pretty easy to make a judgment regarding motivation—a snap versus a slow close," said Lappin. "Most of the time, the animals clamp down with vigor."
For the largest of the living crocodilians—Alligator mississippiensis, or the American alligator—the researchers recorded a bite with 2,125 pounds (964 kilograms) of force.
"If an American alligator bit you, you would have to be able to bench press a small truck to escape, which explains why you simply can't pull apart an alligator's jaws," said Erickson.
The measured bite force of smaller alligators and crocodiles were basically proportional to their size, said Erickson, which allowed the researchers to scale up and estimate a bite force of 18,000 pounds (8,165 kilograms) for SuperCroc, or about the weight of a Mack Truck.
"SuperCroc is not different from crocodiles alive today, just bigger," said Erickson.
Vliet was not at all surprised by the tremendous bite forces of crocodilians:
"I made crude estimates of bite force years ago on large alligators and knew that the forces were large," he said. "I've also been bitten a few times and know from personal experience that the bites have a tremendous crushing force to them."
Into the Wild
Erickson and his colleagues are now preparing to take their research into the wild to see if they get different results.
An alligator bite provoked by the bite bar, they say, is sort of like the reflex that occurs when a doctor taps a patient's knee with a special hammer; the bite response is the same in gators regardless of location. But wild alligators might be in better shape and thus have stronger bites.
"Wild gators move around a lot, catch live prey, and eat hard prey items like turtles," said Vliet. "So the muscles utilized in biting may be better developed than those of captive alligators. Also, since bone density is influenced by nutrition as well as by muscles acting upon the bone, the bones of the head of wild alligators may be stronger than those of captive animals."