"global chronostratigraphic units" (Eon) Phanerozoic Eon (541.0 Ma - present) (Era) †Mesozoic Era (252.17 - 66.0 Ma) (Period) †Cretaceous Period (145.0 - 66.0 Ma) (Epoch) †Gulf Epoch (Stage) †Santonian Stage (86.3 - 83.6 Ma)