Gonzalvo Ballobar, C.Molina, Eustoquio2019-06-032019-06-031992http://hdl.handle.net/10272/16339The quantitative study of the planktic Foraminifera from the Eocene/Oligocene boundary stratotype at Massignano (Apennines, Italy) has been accomplished for the first time, This study allow us to establish the fauna/ changes in the assemblages, showing a progressive decline of the surface dwellers, which are the more tipicai Eocene species that disappear during the Late Eocene. The faunal change is gradual, it accelerates at the Eocene/Oligocene boundary, but there is not evidence of mass extinction. Nevertheless, these extinctions represent about 40% of the total species that lived during the Late Eocene and were partially replaced by oportunistic species. Besides, the quantitative study provides a base for a more rigorous biostratigraphyspaAtribución-NoComercial-SinDerivadas 3.0 Españahttp://creativecommons.org/licenses/by-nc-nd/3.0/es/Planktic ForaminiferaBiostratigraphyChronostratigraphyPaleoecologyEoceneOligocenejournal articleopen access