Systematic taxonomy of exceptionally well-preserved planktonic foraminifera from the Eocene/Oligocene boundary of Tanzania

The Eocene-Oligocene Transition is associated with dramatic climatic change, and disruption and extinction in both marine and terrestrial ecosystems. The diverse assemblages and exceptional state of preservation of planktonic foraminifera in three drilled core-holes through the Eocene/Oligocene boundary in Tanzania (Tanzania Drilling Project Sites 11, 12, and 17) are utilized to illustrate test morphologies and revise species concepts. The taxonomy and phylogenetic relationships of fourteen genera and thirty-five species are discussed and illustrated in thirty plates. Detailed investigations of wall textures and surface ornamentation clarify the species-level and higher taxonomy of the group; three new species are named to fully document the observed range of variation. Evidence for spine holes were found in several species of Dentoglobigerina, and the wall texture, apertural system and symmetry of Cribrohantkenina and its evolutionary origins are discussed. This monograph is intended as a contribution towards the wider goal of updating the taxonomy of all Paleogene planktonic foraminifera by the Paleogene Planktonic Foraminifera Working Group. The extensive illustration and discussion of taxonomic concepts will enable others to form a clearer picture of assemblage variation through the Eocene-Oligocene transition in more typical, less well-preserved material. The monograph will also contribute to a solid foundation for geochemical proxy work based on planktonic foraminifera for this important phase in Earth’s climate history