New insights into the Barremian–lower Aptian calcareous nannofossils of the Mediterranean Tethys: Chronostratigraphic and paleobiogeographic implications

A detailed study of calcareous nannofossil assemblages from twelve uppermost lower Barremian–lower Aptian sections in the Subbetic Domain Betic Cordillera was performed. Seven new species (Crucibiscutum bastetanum, Crucibiscutum gracile, Chiastozygus lamprostauros, Cyclagelosphaera platyaspis, Lithraphidites aichmoides, pugio, and Rhagodiscus sicutclipeus) are described, one is emended (Lithraphidites magnus) taxonomic concept marker Hayesites irregularis discussed clarified. The stratigraphic ranges species, together with those other relevant taxa, determined correlated to standard ammonite biostratigraphy. Age estimates biostratigraphically biohorizons calculated using astrochronologically tuned cyclostratigraphic data. Five subzones proposed which enhance upper Barremian biostratigraphic resolution at a regional scale directly respect Tethyan zonation. Two described here used as markers for newly subzones. duration each subzone provided through astrochronological calibration. This allows refinement zonation Mediterranean–Atlantic province Realm. implications these results regarding extant definition use Barremian/Aptian boundary. morpho-evolutionary trends selected groups reviewed relation latest Barremian–Aptian paleogeographic changes, showing were prominent factor controlling nannoplankton evolution biogeographical distribution west European-Atlantic region.