stratigraphic intervals
   (System) †Jurassic (201.3 - 145.0 Ma)
     (Series) †Middle (174.1 - 163.5 Ma)
       1 (Stage) †Callovian (166.1 - 163.5 Ma)
       2 (Stage) †Bathonian (168.3 - 166.1 Ma)
       3 (Stage) †Bajocian (170.3 - 168.3 Ma)
       4 (Stage) †Aalenian (174.1 - 170.3 Ma)