Ostracods are microscopic, bivalved crustaceans that have a long fossil record in marine and non-marine habitats. The existence of deep-sea ostracod assemblages in today’s oceans have been known since the 19th century Challenger expedition. Benson (1975) first identified the inception of the modern deep-sea ostracod fauna following the establishment of a two-layered ocean about 38 Ma. In later papers (e.g. Benson et al., 1984) he and co-workers recognised 5 major faunal ‘events’ in deep-sea ostracod assemblages that reflected shifts in global climate conditions and re-adjustments of the oceans in response to major tectonic events such the opening and closure of key gateways. As more datasets have become available (via ODP and IODP programs) it has become apparent that these events are not recorded at all sites (e.g. Majoran & Dingle, 2002). This proposed project aims to (1) review the existing literature on deep-sea ostracods and develop a revised quantitative picture of diversity and faunal turnover in Cenozoic deep-sea ostracods, and (2) study additional intervals identified from the ODP/IODP archives. The new database will investigate the spatial pattern of ostracod evolution during key Cenozoic events and consider both palaeodepth and sediment composition as possible explanators of the inconsistencies in such data. Where possible, ostracod shell chemistry and stable-isotope composition will be utilised to support the research.