What Ohio’s fossils record: a trilobite, an armoured fish and two vanished seas
Ohio has two official fossils, and between them they cover more than a hundred million years of the seas that once covered the state.
Ohio was under water for a long time, and the state has written two of its fossils into law.
The older is a trilobite. Section 5.071 of the Ohio Revised Code adopts “Isotelus, a genus of extinct marine arthropod of the class Trilobita, that lived in the seas that covered Ohio during the Ordovician period, about four hundred forty million years ago”. The specimen behind the designation is not a small one: the largest known complete trilobite was found at Huffman Dam in Montgomery County.
The younger and larger is the state fossil fish. Section 5.078 adopts “Dunkleosteus terrelli, a species of extinct arthrodire placoderm fish that lived in the seas that covered parts of Ohio during the Late Devonian period, about three hundred fifty-nine to three hundred eighty-two million years ago”. Dunkleosteus was an armoured predator, and the Cleveland shale it is found in is one of the reasons the species is known at all.
The two designations sit about eighty million years apart, and both describe the same basic fact: the ground Ohio now farms was sea floor, twice over, long before the ice arrived.
The ice is the other half of the story. The glaciers that reached into Ohio flattened the north and west and stopped short of the south-east, which is why the state’s hill country is where it is and its flattest farmland is where it is. Ohio History Central describes this in terms of physiographic regions, including the Central Lowlands and the Appalachian Plateau.
Ohio’s state gem stone belongs to the same story. Section 5.07 adopts Ohio Flint, “a crypto-crystalline variety of quartz” — the stone quarried at Flint Ridge and worked across a wide area of eastern North America for thousands of years.
Read the invertebrate fossil statute: https://codes.ohio.gov/ohio-revised-code/section-5.071
Read the fossil fish statute: https://codes.ohio.gov/ohio-revised-code/section-5.078