The Cenozoic of the Americas does not have a zonation based on Larger Benthic Foraminifera (LBF) unlike the Tethys where there is a shallow-water benthic zonation. Although there were faunal exchanges, the different evolutionary patterns between the Americas and the Tethys require separate zonations. We have calibrated LBF, stratigraphic distributions and events in the Americas using calcareous nannoflora (Paleocene-Eocene), planktic foraminifers (Oligocene-Miocene) and published strontium (Sr) isotope values. We define 29 zones spanning the Paleocene to Recent based on changing LBF assemblages and evolving lineages, with some zonal boundaries related to global or local palaeoenvironmental events. This will allow correlation across carbonate platforms in the tropical Americas at a higher resolution than previously possible.
Mıtchell et al. (Thu,) studied this question.