Prehistoric: Dunkleosteus

Dunkleosteus is a well-known prehistoric fish. Its name "(David) Dunkle" + osteus (οστεος, Greek for bone); meaning "Dunkle's Bone." Named after David Dunkle. David and Jay Terrell (former Museum Curator of Vertebrate Paleontology) discovered the first fossils in 1867. Living during the Late Devonian period, 380-360 million years ago. It weighed about 3.6 tonnes (4.0 short tons) and was up to 10 meters (33 feet) and was also carnivore/piscivore (hypercarnivorous apex predator (meaning its diet was made up 70% of meat, but also ate non-animal foods, such as fruits, fungi, and other plant materials.) and may have been the first apex predator. Its bony plates were up to 5cm thick, although it's pectoral fins were not armored for easier movement.

Dunkleosteus is in order of Arthrodire (Arthrodira), this order of extinct armored jawed fishes (class Placodermi) and was placed in the family Dinichthys. It was the largest of the known species and had the strongest bite of 11,000 pounds (due to the strong jaw muscles) after the C. megalodon, after studying a biomechanical model and scientists at the Field Museum of Natural History and the University of Chicago. The head and thorax had heavy armor, the rest of the body was "naked" without any armor. There is a lack of fear fossils, and mostly it's armored head are found. Because of the armor paleontologists likely say that it was slow, but had powerful muscles to swim.

It had two pairs of sharp-like bony plates, instead of teeth. It could open its mouth in one-fiftieth of a second. Many fish do the same kind of technique. Discovery of unhealed armor bite marks strongly suggested that they cannibalized each other, only when the opportunity was available. Fossils of Dunkleosteus are found with boluses (in the digestion and is a mixture of food and saliva) of other fish and half-digested eaten remains of other fish, because the fossil record shows that it might have had a routine of regurgitated prey bones (instead of digesting them).
When morphological studies were done on the inferognathals (jaw bone) of a juvenile, the adult Dunkleosteus suggest that it went through a change in the jaw morphology and the diet as it aged. The adults aging had more flexible jaws (better to hold struggling prey) and to protect from breakage or injury from other armored prey or enemies. Juveniles had rigid jaws like Coccosteus ("seed bone" and was an extinct genus of arthrodire placoderm).

There are three to four species of Dunkleosteus known so far.
D. raveria, D. amblyodoratus, D. terralli, and D. marsaisi. D. terralli is the largest known species, although Titanichthys was equally as large (8-10 meters).

Posted on April 4, 2019 10:28 PM by backyardcreature