02121nas a2200241   4500000000100000008004100001653002000042653002800062653002600090653002200116653001700138653001600155100002200171700002400193700001700217700001800234245017200252856005300424300002000477490000800497520136000505022001401865       2013                            d10abiostratigraphy10aCalcareous nannofossils10aHelicosphaera inversa10apaleobiogeography10apaleoecology10aPleistocene1 aPatrizia Maiorano1 aFrancesca Tarantino1 aMaria Marino1 aAngela Girone00aMarine Micropaleontology A paleoecological and paleobiogeographic evaluation of Helicosphaera inversa ( Gartner ) Theodoridis and the diachrony of its First Occurrence  uhttp://dx.doi.org/10.1016/j.marmicro.2013.08.001  a14\textendash240 v1043 a<p>The distribution pattern of Helicosphaera inversa (Gartner) Theodoridis is examined from a mid-latitude North Atlantic core (MD01-2446) and two Mediterranean cores (Ocean Drilling Program-ODP Site 975 and Core KC01B) through Marine Isotope Stage (MIS) 13 to 9. The earliest rare occurrences are observed from the uppermost part of MIS 12, while common and continuous abundances characterize MIS 11. The paleoenvironmental framework of the study cores suggests that the taxon thrived in warm surface waters. Correlation with new data from planktonic foraminifera also suggests that H. inversa may have only flourished within a limited salinity range. Comparison with previous findings highlights major diachrony in the FO of the taxon between low and mid-latitude records. It first occurred at lower latitude in the Pacific as early as 0.8 Ma, while in the mid-latitude North Atlantic regions, it is not recorded before 0.51 Ma. The distribution of the taxon in the North Atlantic Ocean also apparently varies in relation with surface water masses and hydrographic fronts. The results suggest that the FO of H. inversa is ecologically controlled and needs to be used with caution in worldwide stratigraphic correlation. Nevertheless, the distribution of the species within the Mediterranean Basin can produce an invaluable ecostratigraphical signal.</p>  a0377-8398