"global chronostratigraphic units"
   (Eon) Phanerozoic Eon (541.0 Ma - present)
     (Era) Cenozoic Era (66.0 Ma - present)
       1 (Sub-era) †Tertiary Sub-era (66.0 - 2.58 Ma) see Period Tertiary Period (66.0 - 2.58 Ma)
       2 (Sub-era) Quaternary Sub-era (2.58 Ma - present) see Period Quaternary Period (2.58 Ma - present)