stratigraphic intervals
   (System) †Jurassic (201.3 - 145.0 Ma)
     (Series) †Lower (201.3 - 174.1 Ma)
       1 (Stage) †Toarcian (182.7 - 174.1 Ma)
       2 (Stage) †Pliensbachian (190.8 - 182.7 Ma)
       3 (Stage) †Sinemurian (199.3 - 190.8 Ma)
       4 (Stage) †Hettangian (201.3 - 199.3 Ma)