The 'Orbulina' is probably a dependable time line at the base of the Burdigalian [Miocene] in deposits of deep-water origin within tropical and warm-temperate areas. 'Orbulina' developed in post-Burdigalian time in temperate areas. Faunal evidence and potassium/argon dates corroborate the approximate correlation of the Saucesian stage of California with the Burdigalian stage of Europe. Orbulina universa is shown to be a final spherical chamber associated with different species and genera of globigerinids.

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