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Devonian World

An Ancient Jaws

Edited from BBC News, 29 November 2006

A prehistoric 'Jaws' which roamed the seas 400 million years ago had the most powerful bite of any known fish.

The extinct creature, Dunkleosteus terrelli, could bring its jaws together with a remarkable force of 5,000 Newtons. This performance surpasses all living fish, including today's great white shark, and puts it up with some of the most powerful bites in all known animals.

US researchers Mark Westneat and Philip Anderson told the Biology Journal of the Royal Society that higher bite forces had only been reported for some large alligators and dinosaurs. Tyrannosaurus rex, for example, could clamp down on its meal with a crushing force of 13,000 Newtons; but a modern spotted hyena, by comparison, exerts a force of only 2,000 Newtons when it cracks bones in its mouth.

The team developed its biomechanical model of Dunkleosteus by studying the fossil remains of the fish, which probably grew up to ten metres in length. The scientists said the way its teeth were organised in the jaw meant that it could focus its bite into a small area - the fang tip - with the incredible pressure of nearly 150 million Pascals.

Even more surprising is the fact that Dunkleosteus could also open its mouth very quickly - in just one fiftieth of a second - which created a strong suction force, pulling fast prey into its mouth.

A Devonian-era Jaws

This heavily armoured fish was both fast during jaw opening and quite powerful during jaw closing, according to Westneat, curator of fish at the Field Museum in Chicago.

This was possibly due to the unique engineering design of its skull and different muscles being used for opening and closing. Usually, a fish has either a powerful bite or a fast bite, but not both. The formidable fish was a placoderm, a diverse group of armoured fish which dominated aquatic ecosystems during the Devonian period, between 415 million to 360 million years ago.

Dunkleosteus was surrounded by possible prey which all required a really high bite force, according to Anderson, working out of the University of Chicago. There were free-swimming, fast animals which all had a hard armour; most of the other fish were other placoderms which had the same hard, bony covering. And then there were large molluscs with hard shells and really large crustaceans. The seas of the Devonian were as busy as those of today.



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