This is a museum quality cast of the lower right jaw of the fearsome prehistoric fish called Dunkeosteus. This jaw cast is approx. 23 inches long, and is composed of high strength gypsum cement. Shown in numerous books, and featured on the cover of "Fossils of Ohio," this king of prehistoric fish lived long before the dinosaurs, about 380 million years ago. Knick-named "terrible Fish", Dunkelosteus was the largest member of the arthrodire order of placoderms or "armored fish" and probably grew to over 20 feet in length. It had a massive skull made of thick boney plates. Some of these plates which served as jaws (including the one featured in this auction) lacked true teeth, but featured sharp beveled edges that acted like self-sharpening cleavers, allowing it to sever its prey in half with one powerful bite. Its torso and tail remains are largely unknown, but are presumed to have been shaped somewhat like a large shark Dunkleosteus terrelli swam in a large, shallow sea that covered much what is now northern Ohio during Devonian times. Its fossils have been found in the grey shales of northern Ohio, along with remains of prehistoric sharks, on which it probably fed. Similar but somewhat smaller species are known from Africa and Europe. Dunkleosteus. which translates "Dunkle's bones," was named for the former Curator of Vertebrate Paleontology at the Cleveland Museum of Natural History, Dr. David Dunkle, who studied this formidable creature. Photos at top show both sides of the jaw cast, and the entire skull. This cast would make a wonderful addition to any fossil collection, a great display item, and very interesting conversation piece.