Dunkleosteus
Dunkleosteus is an extinct genus of large armored, jawed fishes that existed during the Late Devonian period, about 382–358 million years ago. It consists of ten species, some of which are among the largest placoderms to have ever lived: D. terrelli, D. belgicus, D. denisoni, D. marsaisi, D. magnificus, D. missouriensis, D. newberryi, D. amblyodoratus, and D. raveri. The largest and most well known species is D. terrelli, which grew up to 8.79 m (28.8 ft) long[1] and 4 t (4.4 short tons)[2][unreliable source?] in weight. Dunkleosteus could quickly open and close its jaw, like modern-day suction feeders, and had a bite force of 6,000 N (612 kgf; 1,349 lbf) at the tip and 7,400 N (755 kgf; 1,664 lbf) at the blade edge. Numerous fossils of the various species have been found in North America, Poland, Belgium, and Morocco.
The genus name combines David Dunkle's surname with the Greek word ὀστέον (ostéon 'bone'), literally meaning 'Dunkle's-bone'.
Dunkleosteus was named in 1956 to honour David Dunkle (1911–1982), former curator of vertebrate paleontology at the Cleveland Museum of Natural History. The type species D. terrelli was originally described in 1873 as a species of Dinichthys, its specific epithet chosen in honor of Jay Terrell, the fossil's discoverer.[3]
Dunkleosteus is an arthrodire originally placed in the family Dinichthyidae, which is composed mostly of large, carnivorous fish like Gorgonichthys. Anderson (2009) suggests, because of its primitive jaw structure, Dunkleosteus should be placed outside the family Dinichthyidae, perhaps close to the base of the clade Pachyosteomorpha, near Eastmanosteus. Carr and Hlavin (2010) resurrect Dunkleosteidae and place Dunkleosteus, Eastmanosteus, and a few other genera from Dinichthyidae within it.[4] Dinichthyidae, in turn, is left a monospecific family.[5]
The type species, D. terrelli, is the largest, best-known species of the genus, measuring 8.79 m (28.8 ft) in length. It has a rounded snout. D. terrelli's fossil remains are found in Upper Frasnian to Upper Famennian Late Devonian strata of the United States (Huron and Cleveland Shale of Ohio, the Conneaut of Pennsylvania, Chattanooga Shale of Tennessee, Lost Burro Formation, California, and possibly Ives breccia of Texas[6]) and Europe.
D. belgicus (?) is known from fragments described from the Famennian of Belgium. The median dorsal plate is characteristic of the genus, but, a plate that was described as a suborbital is anterolateral.[6]
