"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)
         1 (Epoch) †Early Cretaceous Epoch (145.0 - 100.5 Ma)
         2 (Epoch) †Gulf Epoch