Bryozoans from the Saluda Dolomite show nicely how environmental stress (elevated paleosalinity) reduced faunal biodiversity. Three Saluda localities near historic Madison yielded 19 bryozoan species, largely ramose trepostomes. Most are rare in the lower Saluda, but Homotrypa cincinnatiensis is abundant and Rhombotrypa quadrata and Heterotrypa subfrondosa are common therein, while Batostomella delicutula appears sparsely near the top of the formation. Moving upward in the Saluda, bryozoan species diversity (47 in the Liberty Formation below) drops to 17 low in the lower Saluda, five high in the lower Saluda, and zero above that, before abruptly recovering to 57 in the Whitewater Formation above. This trend indicates steadily rising paleosalinity during the early history of the Saluda lagoon, followed later by abrupt ending of hypersaline conditions therein.
This document was last modified on January 3, 2007.