# Giant prehistoric fish packed quite a bite



## Johnny Thunder (Feb 24, 2006)

Yikes

*Giant prehistoric fish packed quite a bite *
By Will Dunham
Tue Nov 28, 9:34 PM ET

It was the first super predator of the ancient seas and its fearsome, jagged jaws still inspire awe 400 million years later.

The armor-plated fish Dunkleosteus was a 33-foot-long (10 meters), four-ton (3,600-kg) monster that terrorized other marine life in the Devonian Period, which spanned 415 million to 360 million years ago.

While lacking true teeth, Dunkleosteus used two long, bony blades in its mouth to snap and crush nearly any creature unfortunate enough to encounter it.

Scientists at the Field Museum in Chicago and the University of Chicago decided to test Dunkleosteus's reputation for wielding some of the most powerful jaws ever on Earth, creating a biomechanical model to simulate its jaws.

They came away impressed.

In research published on Tuesday in Britain's Royal Society journal Biology Letters, they said the big fish's bite packed 11,000 pounds (5,000 kgs) of force.

The bony blades in its mouth, almost certainly enameled like teeth, concentrated the bite force into a small area at the tip at an astonishing force of 80,000 pounds (36,000 kg) per square inch, they said.

That, the scientists proclaimed, crowns Dunkleosteus as the all-time chomping champion of fish -- sorry, sharks.

"It kind of blows sharks out of the water as far as bite force goes," Mark Westneat, curator of fishes at the Field Museum and co-author of the paper, said in an interview. "A huge great white shark is probably only capable of biting at about half that bite force."

"It puts it with big crocodiles and alligators and big dinosaurs like Tyrannosaurus rex in terms of the most powerful biters ever," Westneat added.

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The researchers also determined that Dunkleosteus could open its mouth very rapidly -- in a 50th of a second -- which formed a suction force drawing prey into the gaping mouth. It is very rare for a fish to possess both a powerful and a fast bite, they said.

Dunkleosteus appeared on Earth about 175 million years before the first dinosaurs and was one of the first jawed vertebrates. It hailed from a group of fish called placoderms, which bore heavy bony armor on the head and neck.

This dominant predator ate just about anything it wanted. The menu included hard-shelled ammonoids with many tentacles, as well as other armored fish, researchers said.

It also probably dined on primitive sharks. In fact, sharks achieved greater size and diversity only after Dunkleosteus and its like went extinct for reasons unclear to scientists.

"Dunkleosteus was able to devour anything in its environment," said Philip Anderson of the University of Chicago, the study's lead author.

To gauge its bite force, Westneat and Anderson used a fossilized skull of the species Dunkleosteus terrelli to recreate its musculature. Their resulting biomechanical model showed the jaw's force and motion, with a skull driven by a unique mechanism based on four rotational joints.

A computer model was developed to simulate skull motions and bite forces.


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