During the Paleocene, the plankton community recovered its diversity after a severe diversity loss at the Cretaceous/Paleogene (K/Pg) boundary. In general, changes in Paleocene deep-sea ostracode fauna are poorly understood. It is still unclear how deep-sea ostracode fauna changed during compelling events such as the K/Pg boundary (66.04 Ma) and the Latest Danian Event (LDE: ~62.18 Ma), a transient Paleocene warming event. In this report, we describe a study on the latest Cretaceous-late Paleocene ostracodes from Integrated Ocean Drilling Program Site U1407, off Newfoundland, in the northwestern Atlantic. Thirty-four ostracode taxa were obtained from 202 discrete samples that were discretely collected from the interval between 66.3 and 57.3 Ma. Near the K/Pg boundary, 8% (2 of 24) of the Maastrichtian taxa became extinct. The extinction rate is estimated to be at most 0.12 E MSY-1, which is in the same range as the background-level extinction rate. Comparing the extinction rates between different ocean basins, the ostracode extinction at the K/Pg boundary displays striking geographical heterogeneity. Between the Maastrichtian and Danian, the ostracode fauna change from a biofacies dominated by shallow bathyal taxa to one dominated by deep bathyal taxa. During the LDE, ostracode fauna display an increase in their benthic ostracode accumulation rates and taxonomic diversity as well as an increase in the relative abundance of Krithe crassicaudata simultaneously with a decline in carbonate content. A similar change is commonly documented in fauna from the northeastern Atlantic during the Paleocene-Eocene Thermal Maximum (PETM; 56.0 Ma). In contrast to the PETM fauna, an extinction event is not recognized. After the Danian, the ostracode fauna indicate changes in water mass and minor environmental disturbances with possible development of corrosive water.
