Giant fish had monster bite

Dec 2 2006

Paris - An armoured fish the size of a small bus that dominated the seas more than 360 million years ago had a bite which makes the great white shark look like a nibbler, a new study says.

The mighty predator, Dunkleosteus terreli, was a placoderm - a group of fishes that had articulated armoured plates which covered their body.

A pair of American scientists who made a computerised model of the skull of a Dunkleosteus say the fish had an extraordinary system of muscles and joints that enabled it to open and close its bladed jaw at terrifying speed and with enormous force.

It could open its jaws and snap them tight in as little as a fiftieth of a second, helped by a suction that drew its helpless prey into its maw.

And it could exert a force of over 4 400 newtons at the razor-edged double fangs at the tip of its jaws and at least 5 300 newtons at its rear dental plates, roughly twice that of a great white shark.

"This bite force capability is the greatest of all living or fossil fishes and is among the most powerful bites in animals," say Philip Anderson of the University of Chicago and Mark Westneat of the Field Museum of Natural History, also in Chicago.

"The only reports of higher bite forces are those found in some extremely large alligators and dinosaurs."

Their paper appears in Biology Letters, published by Britain's Royal Society.

Dunkleosteus lived in the Late Devonian period, between 415 and 360 million years ago, and probably grew to a length of 10 metres.

It gorged on other armoured fishes and primitive sharks, so mobility and jaw strength were vital for it.

The model was based on an adult measuring six metres long and weighed a ton.

The creature with the biggest bite force is believed to have been the Tyrannosaurus rex, which by some estimates could exert a bone-crushing 13 400 newtons, although this figure is debated.