stratigraphic intervals
   (System) †Devonian (419.2 - 358.9 Ma)
     (Series) †Lower (419.2 - 393.3 Ma)
       (Stage) †Emsian (407.6 - 393.3 Ma)
         1 (Biozone) †wenkenbachi Zone
         2 (Biozone) †zorgensis Zone