Ancient Shark's Bite More Powerful Than T. Rex's

A CAT scan of a great white shark. CREDIT: Stephen Wroe et al.

The most powerful bite of all time has been found — that of the prehistoric giant shark Megalodon, which makes that of T. rex look puny.

The giant shark Megalodon, which means "Big Tooth" in Greek, may have grown to more than 50 feet long and weighed up to 110 tons (100 metric tons), at least 30 times as heavy as the largest of its living relatives, the great white shark.

Fossil evidence suggests Megalodon "made a living hunting and killing large whales by biting off their tails and flippers," said researcher Stephen Wroe, a biomechanist and paleontologist at the University of New South Wales in Sydney, Australia.

The researchers used sophisticated computational techniques to analyze the bites of the great white shark and Megalodon, using the kind of software that engineers use to simulate "everything from wingnuts to bridges to space shuttles," Wroe explained.

The 3-D digital models that he and his colleagues developed, based on X-rays of an 8-foot-long male great white, recreate the skull, jaws, muscles of the shark as nearly 2 million tiny connected parts. "It takes a lot of computing power to analyze something as relatively simple as a set of jaws, since you're dealing with all sorts of complex shapes in biology," Wroe said.

There have been many past attempts to figure out just how powerful the bites of great whites are. These seem to have greatly underestimated the power of these sharks, as they typically only dangled small prey in front of the predators. "If it's a relatively small target, and if they are at all unsure what it is they may be biting into — it might be a lump of bone or steel — then it's highly unlikely that you're going to see anything like their maximum bite force," Wrote said.

It turns out the largest great whites have a bite force of up to a whopping 2 tons (1.8 metric tons). That is more than three times that of the bite of an African lion and more than 20 times that of a human. "It's the biggest bite force known for any living animal so far, although it's certainly possible that the killer whale or possibly the larger crocodiles have more powerful bites," Wroe said.

As powerful as great whites are, it turns out their giant extinct cousins greatly surpassed them, generating six to 10 times more bite force, arguably making them the most fearsome predators to ever have lived. In comparison, their estimates for a Tyrannosaurus rex suggest this great "tyrant lizard" was no match for the extinct shark. The dinosaur had a maximum bite force of some 3.1 metric tons, "greater than for a living white shark, but puny compared to 'Big Tooth,'" Wroe said.

"I have to say that I am pretty impressed with just how complex and sophisticated the feeding apparatus of the shark is," Wroe added. "With all the mammalian predators I've looked at, a lot of the muscle force going into the bite is actually lost. The shark has a much more efficient lever system going on."

The fearsome power these hunters could bring to bear makes perfect sense given their lifestyles. "These sharks go after large prey that can hurt them, and they'd rather not get hurt, so they attack with a single horrendously traumatizing bite and then swim back and wait for their prey to die of blood loss," Wroe explained. Other creatures that may hunt with a similar approach include monitor lizards and the allosaur-like dinosaurs.

The bites of these sharks are perhaps especially remarkable, given that they do not have any bones in their skeletons, which are instead made of cartilage, the same kind of tissue making up human ears.

"Even though cartilage is vastly more elastic than bone, cartilage did not result in much lower bite force at all, maybe 5 percent or less," Wroe said. The very flexibility of this system could help explain why they have such effective bites, he added.

Still, pound for pound, the bites of these sharks are not especially powerful. "Most if not all cats and a lot of dog species have more powerful bites, pound for pound," Wroe told LiveScience. "But because these sharks are so big, you have these giant bite forces."

As powerful as the bites of these sharks are, their ability to inflict killer damage on their prey is most likely due to the exquisite design of their formidable teeth. "Their teeth are very sharp, and serrated more or less like steak knives, so they don't need that much force to puncture and tear out flesh," Wroe explained. "And they have a conveyer belt of these teeth — they keep on growing rows and rows of them, so the teeth fall out and are replaced well before they go blunt."

Admittedly, "estimating the bite force in a big dead fish is a tad esoteric," Wroe said, but the methods he and his colleagues used to analyze the jaws of these predators are now helping design better ways to reconstruct people's faces after trauma. "The way in which we model the jaws of a shark are exactly how we'd model the face of a human," Wroe explained.

Their work could also help design better shark-proof equipment. "Large sharks actually do a considerable amount of damage to underwater communications systems," Wroe said.

The scientists are currently investigating a wide range of living and extinct creatures, including giant marine reptiles, terror birds, extinct hominids such as Australopithecus africanus (a close relative of modern humans) and Paranthropus, long commonly known to anthropologists as the Nutcracker Man for its huge jaws. "You can get amazing details about the ecology and evolution of an animal by understanding how it feeds, which is after all a very important part of what animals do," Wroe said.

Wroe and his colleagues will detail their findings in a forthcoming issue of the Journal of Zoology.

The research was funded by the Australian Research Council, University of New South Wales Internal Strategic Initiatives and Australia and Pacific Science Foundation.

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