"global chronostratigraphic units" (Eon) Phanerozoic Eon (541.0 Ma - present) (Era) †Paleozoic Era (541.0 - 251.902 Ma) (Period) †Permian Period (298.9 - 251.902 Ma) (Epoch) †Zechstein Epoch (Stage) †Wordian Stage (266.9 - 264.28 Ma)