Thursday, November 30, 2006
Chicago, Illinois - It could bite a shark in two. It might have been the first "king of the beasts." And it could teach scientists a lot about humans, because it is in the sister group of all jawed vertebrates.
Dunkleosteus terrelli (info) lived 400 million years ago, grew up to 33 feet long and weighed up to four tons. Scientist have known for years that it was a dominant predator, but new embargoed research to be published in the Royal Society journal Biology Letters on November 29 reveals that the force of this predator's bite was remarkably powerful: 11,000 pounds. The bladed dentition focused the bite force into a small area, the fang tip, at an incredible force of 80,000 pounds per square inch.
Even more surprising is the fact that this fish 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. Usually a fish has either a powerful bite or a fast bite, but not both.
"The most interesting part of this work for me was discovering that this heavily armored fish was both fast during jaw opening and quite powerful during jaw closing," said Mark Westneat (homepage), Curator of Fishes at The Field Museum and co-author of the paper. "This is possible due to the unique engineering design of its skull and different muscles used for opening and closing. And it made this fish into one of the first true apex predators seen in the vertebrate fossil record." This formidable fish was a placoderms, a diverse group of armored fishes that dominated aquatic ecosystems during the Devonian, from 415 million to 360 million years ago. Dunkleosteus' bladed jaws suggest that it was among the first vertebrates to use rapid mouth opening and a powerful bite to capture and fragment evasive prey prior to ingestion.
Based on "Feeding mechanics and bite force modelling of the skull of Dunkleosteus terrelli, an ancient apex predator"
(link not working yet:
Placoderms are a diverse group of armoured fishes that dominated the aquatic ecosystems of the Devonian Period, 415-360million years ago. The bladed jaws of predators such as Dunkleosteus suggest that these animals were the first vertebrates to use rapid mouth opening and a powerful bite to capture and fragment evasive prey items prior to ingestion. Here, we develop a biomechanical model of force and motion during feeding in Dunkleosteus terrelli that reveals a highly kinetic skull driven by a unique four-bar linkage mechanism. The linkage system has a high-speed transmission for jaw opening, producing a rapid expansion phase similar to modern fishes that use suction during prey capture. Jaw closing muscles power an extraordinarily strong bite, with an estimated maximal bite force of over 4400N at the jaw tip and more than 5300N at the rear dental plates, for a large individual (6m in total length). This bite force capability is the greatest of all living or fossil fishes and is among the most powerful bites in animals.
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