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This work represents a new contribution to the knowledge on deep-sea ostracods from the western South Atlantic Ocean based on the core GL77 drilled in the Campos Basin (40°02′50″W; 21°12′22″S), 1287 m water depth. Radiocarbon dating and oxygen isotopic analyses in planktonic foraminifera indicate that the 275 cm interval studied of this core comprises the marine isotope stages 1, 2 and 3 (approximately 45 kyr). Forty ostracode species were identified, yet 19 of them are kept in open nomenclature due to either the absence of adult individuals or poor preservation. Thirteen of those species have been recorded previously in the Brazilian continental margin: Bythocypris kyamos , B. affinis , Cytheropteron inornatum, C. perlaria, K. coimbrai, K. morkhoveni, K. sinuosa, K. trinidadensis, Macrocypris adrecta, Microcythere dubia, M. cronini, Poseidonamicus pintoi and Saida ionia. A new Trachyleberididae species, Ambocythere circumporus nov. sp. is proposed, and Cobanocythere ? dubia is reassigned to the genus Microcythere . The stratigraphic distribution of the species in the core GL77 was compared to other studies on deep-sea assemblages carried out in the western Atlantic Ocean. The general species diversity pattern is a significant reduction during the Last Glacial Maximum (LGM) followed by conspicuous changes in Holocene assemblages caused by the appearance of species absent in the Pleistocene. The species Bythocypris kyamos, Cytheropteron perlaria and Saida ionia are restricted to the Marine Isotope Stage (MIS) 1. Poseidonamicus pintoi and Australoecia sp. are predominant and almost exclusive to the MIS 2 and 3. These data indicate the possibility of elaboration of an ostracod-based paleoclimatic zonation for the Quaternary of the south/southeast Brazilian margin. [ABSTRACT FROM AUTHOR] more...

Ostracods from the Turonian–Campanian interval of Jandaíra Formation (Potiguar Basin, NE Brazil) were analysed in terms of diversity, palaeocology and their potential application in sequence stratigraphy. Ternary plots of Cytheroidea, Cytherelloidea, Bairdioidea and Cypridoidea (CCBC plots) were assembled to determine the palaeobathymety purposes. Our results demonstrate the existence of four major palaeoenvironments, as follows: mixohaline/marine 1, marine 1, marine 2 and mixohaline/marine 2, which differ in the taxonomic composition, abundance and ecological preferences of their assemblages. In horizons where the fauna had consistent recovery, it was possible to infer system tracts and stratigraphic surfaces. The inferred sequence boundaries are indicated by important faunal changes, expressed mainly by reduction in diversity, differences in the assemblages' compositions and their ecological preferences; the maximum flooding surfaces (MFS) were marked by high diversity of marine stenohaline taxa. The results of this study reinforce the usefulness of ostracod assemblages in sequence stratigraphy interpretation in the marine and marginal marine successions. [ABSTRACT FROM AUTHOR] more...

• Sahune (Oxfordian, Late Jurassic) in south-eastern France Basin is newly described. • Carbonate bodies enclosed within Terres Noires Formation formed at cold seeps. • Associated fauna indicate seepage at bathyal depth ca. 1.500 m. • Several seep ostracod families have evolved at seeps since the Oxfordian. • Colonization of bathyal environments occurred earlier than thought. Hydrocarbon seeps represent some of the most extreme marine habitats but are also home to rich communities developed around chemosynthesis rather than photosynthesis. Here we describe the outcrop of Sahune (Drôme department, south-eastern France), that illustrates a new seeping site during the Late Jurassic (middle Oxfordian), as formally demonstrated by geochemical proxies. We report the associated fauna composed of foraminifers, radiolarians, crinoids, echinoids and ostracods that all point to seepage at bathyal depth. The foraminifer assemblage and the occurrence of the irregular echinoid Tithonia oxfordiana together point to a middle Oxfordian age. We provide an in-depth analysis of the ostracod community, which is the oldest so far reported in such environments. The new species Procytherura praecoquum may be cognate to the seepage site and could illustrate the oldest known example of pore clusters, sometimes proposed as representing ectosymbiosis. The Sahune assemblage demonstrates that cold seep ostracod communities were already a mixture of taxa from platform and deep-sea oligotrophic environments. The post-Jurassic diversification of ostracods at cold seeps was related to colonization events and diversification of families that have been inhabitants of such ecosystems at least since the Oxfordian. The Sahune record changes our current conception of the deep-sea colonization by the ostracods Tethysia and Procytherura that occurred earlier than traditionally considered. [ABSTRACT FROM AUTHOR] more...