Bite me !

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

The armour-plated fish Dunkleosteus was a 10 metre long, 3600kg monster that terrorised 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' 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 5000kg of force.

The bony blades in its mouth, almost certainly enamelled like teeth, concentrated the bite force into a small area at the tip at an astonishing force of 36,000kg 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.

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.