The Museum has some of the world’s best fossil specimens of Dunkleosteus terrelli (or "Dunk," as he's known in the Museum), including the giant armored skull on display in Kirtland Hall. Dunk was one of the fiercest creatures alive in the Devonian “Age of Fishes,” about 360 million years ago. Up to 20 feet in length and weighing as much as two tons, this predator was capable of snapping a prehistoric shark in two with its razor-sharp, self-sharpening jawbones. These long-extinct fishes lived in the Cleveland area, which was covered by a shallow sea. A rich variety of fossil fish from the Late Devonian have been uncovered in the Cleveland Shale, which is made up of sediment left behind by this prehistoric ocean. Dunkleosteus is named for former Museum curator of vertebrate paleontology Dr. David Dunkle.