"global chronostratigraphic units"
   (Eon) Phanerozoic Eon (541.0 Ma - present)
     (Era) †Mesozoic Era (252.17 - 66.0 Ma)
       1 (Period) †Triassic Period (251.902 - 201.3 Ma)
       2 (Period) †Jurassic Period (201.3 - 145.0 Ma)
       3 (Period) †Cretaceous Period (145.0 - 66.0 Ma)