Ancient predator had strongest bite of any fish, rivaling bite of large alligators and T. rex

Ancient predator had strongest bite of any fish, rivaling bite of large alligators and T. rex

A photograph of the Dunkleosteus terrelli fossil skull upon which this study was based. Scientists created a biomechanical model to simulate the jaw's function. From that they determined muscle mass and bite force. This ancient fish had a bite that exerted 11,000 pounds of force, the strongest bite of any fish ever, and one of the strongest bites of any animal, rivaling the bite of large alligators and Tyrannosaurus rex. 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. Credit: Photograph by Michael LaBarbera, courtesy of The Field Museum
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 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, 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.

To determine the bite force, scientists used the fossilized skull of a Dunkleosteus terrelli to recreate the musculature of the ancient fish. This biomechanical model showed the jaw..s force and motion, and revealed a highly kinetic skull driven by a unique mechanism based on four rotational joints working in harmony. The extinct fish had the strongest bite of any fish ever, and one of the strongest bites of any animal, rivaling the bites of large alligators and Tyrannosaurus rex.

Thus Dunkleosteus was able to feast on armored aquatic animals that also lived during the Devonian, including sharks, arthropods, ammonoids, and others protected by cuticle, calcium carbonate, or dermal bone.

..Dunkleosteus was able to devour anything in its environment,.. said Philip Anderson, at the Department of Geophysical Sciences at the University of Chicago and lead author of the research. The bladed jaws, capable of ripping apart prey larger than its own mouth, is a feature sharks didn..t develop until 100 million years later.

..Overall, this study shows how useful mechanical engineering theory can be in studying the behavior of fossil animals,.. he added. ..We cannot actually watch these animals feed or interact, but we can understand the range of possible behaviors by examining how the preserved parts are shaped and connected to each other...

Source: Field Museum
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Genome Of Ancient Fish Could Reveal Evolutionary Mysteries, Stanford Scientists Say

STANFORD, Calif. A prehistoric fish that until 1938 was thought to be extinct has caught the eye of geneticists at the Stanford University School of Medicine who hope to sequence the ancient genome to learn how animals evolved to live on land. The 5-foot, 130-pound fish in question, called the coelacanth, ekes out an existence in cool, deep-water caves off the Comoro Islands in the Indian Ocean and northern Indonesia. Its lobed fins, skeleton structure and large, round scales are practically unchanged from its fossilized ancestors. This resemblance is what makes it an attractive target for sequencing, according to work published in this week's online issue of Genome Research.

Genetics professor Richard Myers, PhD, co-authored the paper, which makes the case for sequencing the coelacanth genome. "It's just making an argument that if we want to understand this level of evolution, this is what we need to do," he said. The next step is convincing a funding agency, such as the National Institutes of Health or the Department of Energy, to add the coelacanth to a list of high priority organisms to sequence.

Geneticists often compare gene sequences between species to learn how traits evolved. To learn what makes a mammal a mammal, for instance, they may compare a gene sequence in humans, mice, dogs, chickens and frogs to see what sequences the mammals share and that frogs and chickens lack. If all the mammals have one sequence in common, it is likely to be important for making milk, growing hair or other features unique to mammals.

This type of analysis has been all but impossible for learning how land animals crawled ashore and developed limbs and lungs. The problem is this: as fish evolved they went through a flurry of genetic alterations, making fish species almost as different from each other as they are from land animals. Given this vast diversity, a sequence in land animals that's missing in one of the fish species is not necessarily involved in land animal biology, according to James Noonan, PhD, who did the coelacanth work as a graduate student at Stanford with Myers, the Stanford W. Ascherman, MD, FACS Professor in Genetics. That genetic difference may just be the result of random changes in that particular fish.

In contrast, the coelacanth seems to have changed very little--physically or genetically--since one wayward branch of the fish family headed for land roughly 360 million years ago. Because it has changed so little the coelacanth is ideal for genetic comparisons. Any genetic feature found in all land animals but lacking in the coelacanth could represent a change that makes living on land possible.

Noonan said that coelacanth's close relative, the lungfish, could also fill in the genetic gap between land animals and fish, but the coelacanth has one practical advantage: "The lungfish genome is enormous," said Noonan, who is now a postdoctoral fellow at the Lawrence Berkeley National Laboratory. At 35 times the size of the human genome, sequencing the lungfish is an unlikely proposition. In contrast, the coelacanth genome is smaller than that of either humans or mice.

To make his case for the coelacanth, Noonan sequenced a group of coelacanth genes called the protocadherin gene cluster. He chose this region because it is extremely variable between different species, making it easy to see differences and similarities. This region has 54 genes in humans and 97 genes in the zebrafish, whose genome has been sequenced. He found that the coelacanth had 49 genes in the cluster, much like humans and other land animals. What's more, humans and coelacanths both have subgroups of these genes that zebrafish lack. "The coelacanth is evolving very slowly, that's what makes them interesting," Noonan said.

Although it isn't known why coelacanths evolve so slowly, Noonan suggested that their lifespan might be at issue. Where most fish reproduce quickly and have short generation times, the coelacanth reproduces slowly and gives birth to live young. This means that the coelacanth has had fewer generations of offspring to accumulate mutations.

The fact that coelacanth is available for sequencing is a lucky accident. They were thought to be extinct until 1938 when museum curator Marjorie Courtaney-Latimer discovered a specimen in a fisherman's catch near Cape Town, South Africa. In 1998 a honeymooning researcher found a second population off the coast of Indonesia.

Last year Myers and David Kingsley, PhD, professor of developmental biology, successfully recommended that a fish called the stickleback be added to the list of organisms to be sequenced by the National Human Genome Research Institute at the NIH. Myers said he, Noonan and other researchers who contributed to the article in Genome Research will be submitting the coelacanth for consideration soon.

Other Stanford researchers at the Stanford Human Genome Center who contributed to this work include Jane Grimswood, finishing group leader; Jeremy Schmutz, informatics group leader, and Mark Dickson, production sequence group leader