Resumen de On the size change of benthic foraminifers of the Bathyal zone during the Oligocene-Quaternary interval
A detailed study of the eleven most abundant benthic foraminiferal species found in the Oligocene through Quaternary deposits of eight reliable DSDP sites (504 samples) located in the bathyal zone of the Atlantic and Pacific oceans revealed that Oligocene specimens are considerably smaller than Quaternary ones, and that increase of the mean size since the Oligocene went more or less gradually until the Pliocene inclusively. Quaternary specimens, however, showed a decrease in size in several sites with respect to Pliocene specimens, although they still were considerably larger than their conspecific individuals recovered in Oligocene beds. One possible explanation of this phenomenon are favorable life conditions in the bathyal zone for the majority of the foraminiferal species during the entire Oligocene-Pliocene interval.
