Marine Communities

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Rocks that formed in a sea covered Oklahoma during the Ordovician Period, about 455 million years ago.

Although Oklahoma is now a land-locked state far from the coast, it was covered by shallow seas at times in the past. Most of Oklahoma's fossils were animals that lived in these seas. Click below to learn about communities from the Cambrian, Ordovician, Silurian-Carboniferous and Cretaceous periods.