"global chronostratigraphic units" (Eon) Phanerozoic Eon (541.0 Ma - present) (Era) †Mesozoic Era (252.17 - 66.0 Ma) (Period) †Jurassic Period (201.3 - 145.0 Ma) (Epoch) †Dogger Epoch (Stage) †Aalenian Stage (174.1 - 170.3 Ma)