Dunkleosteus

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Dunkleosteus
Dunkleosteus-fig4b-Ferron-Martinez-Perez-Botella-2017.jpg
Scientific classification

Dunkleosteus was a large Placoderm (arthropod fish) that lived in the late Devonian period, about 380–360 million years ago. It grew to 10 metres (33 feet), and was the top predator of its time and one of the top predators of the Paleozoic era.

Description

Dunkelosteus belongs to the Placodermi, a family of armour-plated fishes. More precisely, it was an arthodire - one of the more advanced members of the placoderm fish.

Dunkelosteus was probably the largest member of the placoderms, and the largest animal up to that time, which would stay that way until the evolution of the dinosaurs. The Placodermi first started appearing in the Silurian, and all of them were extinct by the late Devonian. There are no modern descendants.

Dunkleosteus had one of the most powerful bite of any fish, well ahead of all modern-day sharks, including the Great White shark.

Dunkleosteus could concentrate a force of up to 8,000 pounds (3,628 kg) per square inch at the tip of its mouth, effectively placing Dunkleosteus in the league of Tyrannosaurus rex and modern crocodiles as having the most powerful known bite. Dunkleosteus could also open its mouth in one-fiftieth of a second, which would have caused a powerful suction that pulled the prey into its mouth, a food-capture technique reinvented by many of the most advanced teleost fishes today. Due to its heavily armoured nature, Dunkleosteus was likely a relatively slow (albeit powerful) swimmer. By Devonian standards, Dunkleosteus was one of the most highly evolved animals. It was one of the earliest jawed fishes. Instead of actual teeth, Dunkleosteus possessed two long, bony blades that were extensions of its jaw that could slice through flesh and snap and crush bones and almost anything else. These plates also sharpened themselves every time the fish closed its mouth.

It was a vicious, gluttonous hunter, and probably ate whatever hapless creature it could overpower. The discovery of Dunkleosteus armor with unhealed bite marks strongly suggest that they cannibalized each other when the opportunity arose. Frequently, fossils of Dunkleosteus are found with boluses of fish bones, semi-digested and partially eaten remains of other fish. As a result, the fossil record indicates that it may have routinely regurgitated prey bones rather than digesting them.

Cladoselache did not prey on Dunkleosteus, it was the other way around. It is commonly thought, and commonly said that placoderms, such as Dunkleosteus, were outcompeted by the smaller, swifter fishes, such as the early shark Cladoselache. However, this assessment fails to take into account that predatory placoderms would have inhabited different ecological niches than the early sharks during the Devonian period. As such, claiming that Cladoselache was a more efficient predatory fish than Dunkleosteus because the former was apparently faster than the latter would be akin to saying that the orca is a superior marine predator than the swordfish because orcas have teeth. Dunkleosteus may have also been one of the first animals to internalize egg fertilization, and thus sexually reproduce in the manner that most mammals do today.

Although Placoderms only existed for 50 million years, their mark on the fossil record is quite visible. They were a pioneer in the later scenes of the Paleozoic, and were vital to the success of the vertebrates. The Placoderms died out in the late Devonian for reasons that are still not well understood.

Dunkleosteus remains have been found in late Devonian strata in Morocco, Belgium, Poland, and North America.

Mouth

Dunkleosteus may have had a skin covering its teeth making it resemble a beluga whale.

References

http://www.livescience.com/1161-prehistoric-fish-powerful-jaws.html

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