Coccolithophorids and Related Nannoplanktons from the Cretaceous-Tertiary Sequence of Khasi Hills, Assam

This paper reports for the first time the occurrence in India of fossil Coccolithophores and related nannoplanktons from the Cretaceous-Tertiary sequence of Assam. This study has been undertaken to see whether the Cretaceous-Tertiary boundary can be established on the basis of this group of microfossils, and whether or not the same can be applied successfully for delimiting biostratigraphic zones. A short account of the method of preparation and study, taxonomy and systematic descriptions of the forms studied with their synonymies is given. One new species (?) Coccolithus reticulatus and following forms, Coccolithus grandis, Coccolithites sp. Braarudosphaera bigelowi, Marthasteritts tribrachiatus, M jurcatus, M. inconspicuus, and Lucianorhabdus cayeuxi are reported.