"global chronostratigraphic units"
Count: 5e; †118;85e
   (Eon) Phanerozoic Eon (541.0 Ma - present)
  Count: [*†*] 4e; †114;63e
     (Era) Cenozoic Era (66.0 Ma - present)
    Count: [*†*] 3e; †16;9e
       (Sub-era) †Tertiary Sub-era (66.0 - 2.58 Ma) see Period Tertiary Period (66.0 - 2.58 Ma)
      Count: [†*] †16;7e
         (Period) †Paleogene Period (66.0 - 23.03 Ma)
        Count: [†*] †8;3e
           (Epoch) †Oligocene Epoch (33.9 - 23.03 Ma)
          Count: [†*] †2
             (Stage) †Chattian Stage (27.82 - 23.03 Ma)
            Count: -