From Ohio History Central
Without question, the best-known and most popular fossil organisms are the dinosaurs. Many people wonder if dinosaurs have been found in Ohio or lived in Ohio. During the Mesozoic Era, when dinosaurs and other reptiles were the dominant forms of life, Ohio was above sea level as an upland land mass. Undoubtedly, dinosaurs roamed the Ohio land but erosion, rather than deposition was the dominant geologic force. Dinosaur remains that may have been entombed in lake or river sediments were destroyed during the 300-million-year long interval of erosion that removed huge amounts of rock. Therefore, unless an isolated deposit of Mesozoicrocks is discovered in Ohio, no dinosaur remains will ever be found in the state.
- Hansen, M. C., 1996. "Phylum Chordata--Vertebrate Fossils," in Fossils of Ohio, edited by R. M. Feldmann and Merrianne Hackathorn. Ohio Division of Geological Survey Bulletin 70, p. 288-369.