stratigraphic intervals
   (System) †Cretaceous (145.0 - 66.0 Ma)
     (Series) †Lower (145.0 - 100.5 Ma)
       (Subseries) †Neocomian
         (Stage) †Hauterivian (132.6 - 129.4 Ma)
           1 (Substage) †upper
           2 (Substage) †lower