In this study, we employ ecological niche modeling, a quantitative method of analyzing ecological biogeographic patterns, which has been shown to be successful in studies of modern biota. Quantitative paleobiogeographic analyses require a large, densely sampled outcrop belt, well-defined stratigraphy, and large quantities of paleontological information on species occurrences throughout the outcrop belt. The Cincinnati Arch possesses these parameters making it an attractive field area for a paleobiogeographic study. The geographic distribution of several Cincinnatian (Late Ordovician) articulate brachiopod species ranges was modeled using GIS (Geographic Information Systems) and GARP (Genetic Algorithm using Rule-set Prediction). Data used to construct this model was obtained from field work, published literature and unpublished theses and dissertations. Environmental parameters obtained from this data, such as inferred water depth, percent silt, and biofacies, were utilized in the ecological niche model.
Niche modeling analyses accurately predicted several brachiopod species ranges in the Cincinnatian Series. Geographic range of those species contracted during the relative drop in sea level. Niche modeling analysis of species across multiple time slices demonstrate habitat tracking as a result of the regression. Results show that for shallow marine fauna a drastic decrease in geographic area caused by a relative sea level drop has negative effects on biogeographic diversity patterns.
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