SIGNIFICANCE OF THE BRADYINIDAE AND PARAJANISCHEWSKINA N. GEN. FOR BIOSTRATIGRAPHIC CORRELATIONS OF THE LATE VISEAN (MISSISSIPPIAN) IN WESTERN PALEOTETHYAN BASINS

摘要

Members of the Bradyinidae in some British and Irish upper Visean sections have been analyzed, especially the first occurrence of "Janischewskina" in the basal Brigantian stratotype, at the Janny Wood section (northern England). Most specimens of "Janischewskina" illustrated from the British sections show a distinctive keriothecal wall in some of the final septa that is the basis for creating Parajanischewskina brigantiensis n. gen. n. sp. The genera of the family Bradyinidae are considered excellent markers for the zonation of the late Visean in western Paleotethyan basins. Thus, Bradyina first occurs near the end of the late Asbian, Parajanischewskina at the beginning of the Brigantian, Parabradyina in the middle part of the early Brigantian, and Janischewskina at the beginning of the late Brigantian.