The extinction of the Hantkeninidae, a planktonic family of foraminifera became generally accepted as marking the Eocene-Oligocene boundary; in 1998 Massignano in Umbria, central Italy, was designated the Global Boundary Stratotype Section and Point (GSSP).
في كومنز صور وملفات عن: العصر الإيوسيني مقياس زمني جيولوجي حفرة ميسيل The extinction of the Hantkeninidae, a planktonic family of منخربات became generally accepted as marking the Eocene-Oligocene boundary; in 1998 Massignano in أومبريا, central Italy, was designated the Global Boundary Stratotype Section and Point (GSSP).