stratigraphic intervals
   (System) †Devonian (419.2 - 358.9 Ma)
     (Series) †Upper (382.7 - 358.9 Ma)
       (Stage) †Frasnian (382.7 - 372.2 Ma)
         1 (Substage) †P. gigas + P. triangularis Zones
         2 (Biozone) †A. triangularis Zone
         3 (Biozone) †A. asymmetricus Zone