Temporal and spatial distribution of ostracodes across the Pennsylvanian–Permian boundary interval in eastern North America

Ostracodes recovered from eastern North American coal measures in the Appalachian, Illinois, and Maritimes Basins have the potential to resolve the temporal and spatial relationships of the strata deposited during the Pennsylvanian–Permian boundary interval. The ostracode associations include: (1) a Pennsylvanian (Virgilian; Gzhelian) marine association dominated Hollinella cushmani with abundant brachiopods and foraminifera exclusive to the GIL 30 Core in Kentucky (Illinois Basin); (2) a latest Pennsylvanian (Virgilian; Gzhelian) brackish association dominated by Geisina upsoni (Kellet), Cavellina nebrascensis (Geintz), and Velatomorpha fittsi (Kellet) exclusive to the GIL 30 Core in Kentucky (Illinois Basin); and (3) an uppermost Permian (Asselian/Sakmarian) association of nonmarine taxa dominated by Whipplella cuneiformis (Holland), Whipplella parvula (Holland), Paleodarwinula hollandi (Scott), and Haworthina bulleta (Harris and Lalicker) that occurs in the uppermost continental facies of both the Illinois and Dunkard Basins. A comparable nonmarine association of Paleodarwinula hollandi and Whipplella bretonensis (Copeland) occurs in the Bolsovian to Cantabrian (Moscovian to Kasimovian) coal measures of the Maritimes Basin of Atlantic Canada. The data presented herein provides new information about the withdrawal of marine waters from several major Late Paleozoic basins in eastern North America. Mid-continental marine influence persisted into the latest Pennsylvanian to earliest Permian during deposition in the eastern Illinois Basin on the western Appalachian coastal plain. The uppermost nonmarine association of nonmarine Ostracoda in both the Illinois Basin and Dunkard Basin indicates a synchronous development of aquatic freshwater faunas during Lower Permian times. With increasing geographic isolation of the eastern North American basins, the dispersal and radiation of Ostracoda in these basins was apparently facilitated by brood rearing as demonstrated by the dominance of the Platycopina and Darwinulocopina.