A Cenozoic time-scale — some implications for regional geology and paleobiogeography



Recent data generally substantiate the most recent incarnation of the Cenozoic time-scale (Berggren, 1969c). Newly obtained dates in the type section of the Chattian (Upper Oligocene) support a previous suggestion that a hiatus may separate the top of the stratotype Chattian from the base of the stratotype Aquitanian. The Orbulina Datum is placed at 16 my and the Globigerina nepenthes at 13.5 my. The junction of Eurasia and Africa in the early Miocene (ca. 18 my ago) and of Europe and Africa in the middle Miocene (ca. 15 my ago) markedly affected the Tethyan paleogeography and, concomitantly, the biogeographic dis tribution of larger and smaller Foraminifera, as well as various land mammal groups, including hominoids.