The Paleocene (pronunciation: /ˈpæliəˌsiːn, ˈpæ-, -lioʊ-/; symbol Pε) or Palaeocene, the "old recent", is a geologic epoch that lasted from about 66 to 56 million years ago. It is the first epoch of the Paleogene Period in the modern Cenozoic Era. As with many geologic periods, the strata that define the epoch's beginning and end are well identified, but the exact ages remain uncertain.