Abstract

The framebuilding fauna of an Early Silurian (Aeronian, Llandoverian), Brassfield Formation reef from west-central Ohio is examined in detail. Brassfield reefs are among the very few Silurian reefs of the midcontinental United States that are not dolomitized. Species-level taxa identified in the framebuilding fauna include two favositid corals, two proporid corals, two halysitid corals, two colonial rugosan corals, and at least four stromatoporoids.

Favositids, halysitids, crinoid holdfasts, and bryozoans are distributed fairly evenly across the reef; colonial rugosans and solitary rugosans are more abundant along the windward side of the reef; and stromatoporoids are more abundant on the leeward side. The Brassfield reef fauna resembles that from the Jupiter Formation (Aeronian), Anticosti Island, and the Manitoulin Formation (Aeronian), Manitoulin Island; however, there are differences in total diversity and composition. Paleogeographic positioning, local water depth, and access to open-ocean circulation are inferred as reasons for the differences among the Aeronian reefs.

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