358 years ago, a shallow sea teeming with marine life covered Northeast Ohio. Dunkleosteus terrelli, the largest predator and one of the fiercest creatures alive in the Devonian “Age of Fishes,” ruled the subtropical waters. Up to 20 feet in length and weighing more than 1 ton, this arthrodire fish was capable of chopping prehistoric sharks into chum! Dunkleosteus had a massive skull made of thick, bony plates, and 2 sets of fang-like protrusions near the front of powerful, self-sharpening jawbones.

In 1966, the Ohio Department of Transportation (ODOT) began construction on Interstate 71 in the shale-rich Big Creek Valley—a treasure trove of sediment and fossil material. Under the leadership of then-Director William Scheele, a team of Museum researchers led by Bill Hlavin worked in collaboration with ODOT to excavate an immense volume of fossil-bearing shale concretions from the construction site. A rich variety of fossil fish and plants from the Late Devonian were uncovered, and continue to be found in the Cleveland Shale today.

The Museum has some of the world’s best-preserved Dunkleosteus terrelli fossils, including the giant armored skull on display in Kirtland Hall of Prehistoric Life, nicknamed “Dunk." Dunkleosteus terrelli is named for former Museum Curator of Vertebrate Paleontology Dr. David Dunkle and Jay Terrell, who discovered the first fossils of the “terrible fish” in 1867. Ohio lawmakers designated Dunk the official state fossil fish in 2021.


  • Title: Dunkleosteus terrelli
  • Date: 1931-08-03
  • Type: Natural object
  • Taxonomy: Animalia, Chordata, Placodermi, Arthodira, Dunkleosteidae, Dunkleosteus
  • Specimen Number: CMNH 6090
  • Rock Unit: Cleveland Shale
  • Preparation: mount
  • Geological Period: Paleozoic, Devonian, Late, Famennian
  • Geography: Ohio, United States
  • Department: Vertebrate Paleontology
  • Collector: Peter A. Bungart & F. G. Sheperd
  • Age: 360-358.9 million years

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