stratigraphic intervals
   (System) †Triassic (251.902 - 201.3 Ma)
     (Series) †Upper (237 - 201.3 Ma)
       (Stage) †Norian (227 - 208.5 Ma)
         1 (Substage) †upper see Substage Sevatian Substage
         2 (Substage) †middle see Substage Alaunan Substage
         3 (Substage) †lower see Substage Lacian Substage