-This study presents the taxonomy of benthic foraminifera, ostracods, and radiolarians of a sedimentary succession within the Lachman Crags Member, Santa Marta Formation (upper Santonian-lower Campanian), northwestern James Ross Island. Twenty-seven benthic foraminiferal species, six ostracod species, and six radiolarian species were identifi ed. Calcareous microfossils occurrences are restricted to few stratigraphic levels described as tuffaceous sandstones cemented by calcium carbonate, while siliceous microfossils and agglutinated foraminifera also occur in different lithofacies. This suggests a preservational bias in the occurrences of microfossils within the studied section, possibly related to the presence/absence of calcium carbonate cement. The benthic foraminiferal fauna presents a low degree of endemism with the dominance of cosmopolitan taxa (e.g. Gyroidinoides globosus (Hagenow), Gavelinella sandidgei (Brotzen). Consistent occurrences of G. globosus suggest the dominance of deep-neritic to upper-bathyal paleodepths. The ostracod genera identifi ed herein have already been reported for the Cretaceous of the Gondwana region and suggest deposition on a shelf with warm water temperature and normal salinity. The studied radiolarian fauna, the fi rst one described for the James Ross Island region, can be considered Late Cretaceous in age, also presenting the dominance of robust (dissolution resistant) cosmopolitan taxa.

-The ODP, Site 1001B (Leg 165), located in the Caribbean Sea, presents a well preserved sedimentary succession ranging from the Cretaceous to the Neogene that consists predominantly of pelagic limestone. The main objective of this article is to study taxonomically the Maastrichtian radiolarian and the Maastrichtian-early Danian ostracode faunas recovered in the studied site and to compare them to faunas previously described elsewhere. Despite the discontinuity of the occurrences and the scarcity of specimens, 45 radiolarian species and seven ostracode species assigned to six genera, were identified. The radiolarians were recovered only in the cores 21R and 20R and correspond to a typical Upper Cretaceous fauna, containing even species considered as index fossils such as Orbiculiforma renillaeformis (Campbell & Clark) Pessagno. The seven ostracode taxa occur in the Maastrichtian-early Danian interval. The single specimen of Paleoabyssocythere sp. here recorded could not be ascribed to none of the described species and possibly constitutes a new taxon. The presence of the ostracode association Paleoabyssocythere-Krithe-Bairdoppilata-Cytherella suggests deposition in a bathyal or outer shelf environment.