GIS-BASED MAPPING OF BRACHIOPOD SPECIES RANGES IN THE TYPE CINCINNATIAN

Sea-level fluctuations during the Cincinnatian Series (Late Ordovician) instigated a series of faunal turnover events in the Cincinnati, Ohio region including species invasions, species range fluctuations, and species migrations due to habitat tracking. These strata have been extensively studied in terms of their biodiversity, paleoecology, and sequence stratigraphy. Previous paleobiogeography analyses of these units, however, have not considered biogeographic patterns at the level of individual species at fine spatial or temporal scales. The excellent preservation and history of intensive sampling within the tri-state (Ohio, Kentucky, Indiana) area provide an excellent framework in which to study paleobiogeographic changes using Geographic Information System (GIS) methods.

GIS was used to reconstruct species ranges both spatially and temporally (at the level of formation member) for articulate brachiopod species from the Fairview through the Whitewater Formations (Maysville to Richmondian Stages). Data for brachiopod range reconstruction included collections from three museums (Cincinnati Museum Center, Limper Geology Museum of Miami University, and Orton Geological Museum of Ohio State University). Geographic distribution and migration patterns of brachiopod species were examined graphically in order to quantify the timing and extent of range expansions and contractions, as well as their relationship to events such as regional sea-level fluctuations.

The geographic area of brachiopod species ranges was statistically correlated with regional sea level; species ranges increased during transgressions and vice versa. Additional inspection of ranges of individual species through multiple time slices allowed discernment of a clear pattern of habitat tracking. Range maps clearly display the migration of brachiopod species in response to lateral movement of their ecologically preferred environment up and down the Cincinnati ramp system through time.