Coiling directions in some Miocene planktonic Foraminifera

Abstract. We have measured the coiling directions of approximately 14 000 Miocene planktonic Foraminifera shells belonging to three lineages (Dentoglobigerina altispira, Paragloborotalia mayeri and Fohsella spp.) from sites in the Pacific (ODP Site 871) and Atlantic (ODP Site 925) oceans. Stratigraphic patterns in the preferred direction of coiling of these forms are assessed and their potential utility for biostratigraphic correlation is discussed. We find that all three lineages show a transition from approximately random coiling (although with a slight discernible sinistral bias in D. altispira) to sinistral predominance in both oceans, although the timing and pattern of change is different in each case.