Coral Fossils

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Carboniferous Coral and Brachiopod Reef.jpg
Phylum Brachiopoda - Spiriferella sp.; Phylum Cnidaria, Class Anthozoa - Barbouria sp. (Coral) Age: Lower Pennsylvanain Location: Ely Formation, Millard County, Utah

Corals (Phylum Cnidaria, formerly called Coelenterata) are solitary or colonial, filter-feeding and predatory animals that build a skeleton of calcium carbonate. The cnidaria also includes such soft-bodied forms such as jellyfish. Corals range from Ordovician to Recent and are prominent fossils in Ordovician through Devonian rocks in Ohio. They are somewhat rare in Mississippian and Pennsylvanian rocks. In particular, Silurian and Devonian carbonate rocks in Ohio contain an abundant and diverse coral fauna. At least 70 species are known from Devonian rocks in the state.

Corals in Paleozoic rocks in the state are of two forms. Solitary, or rugose corals are cone-shaped or irregular tube-shaped and contained a single coral animal. The pointed end of the coral was anchored to the sea bottom and the animals food-gathering tentacles were present on the open end. Sometimes rugose corals are called horn corals because of their resemblance to a cow horn. Most specimens are an inch or two in length.

Colonial, or tabulate, corals consist of many identical coral animals that build a skeletal structure of calcium carbonate. Some individual coral “heads” can be up to three feet in diameter. “These organisms were major reef builders during the Silurian and Devonian and can be found in abundance. Common genera are Favosites, which is sometimes called a honeycomb coral because of its resemblance to honeycombs, and Halysites, which is commonly called a chain coral because the individual corallites are linked in chain-like fashion.

See Also



  1. Babcock, L. E., 1996. "Phylum Cnidaria," in Fossils of Ohio, edited by R. M. Feldmann and Merrianne Hackathorn. Ohio Division of Geological Survey Bulletin 70, p. 70-89.