"global chronostratigraphic units"
   (Eon) Phanerozoic Eon (541.0 Ma - present)
     (Era) †Paleozoic Era (541.0 - 251.902 Ma)
       (Period) †Carboniferous Period (358.9 - 298.9 Ma)
         (Subperiod) †Pennsylvanian Sub-period (323.2 - 298.9 Ma)
           (Epoch) †Gzelian Epoch see Age Gzhelian Age (303.7 - 298.9 Ma)
             1 (Stage) †Klazminskian Stage
             2 (Stage) †Noginskian Stage