The Cenozoic (also Cænozoic or Cainozoic) Era (pronounced /ˌsiːnɵˈzoʊɪk/, /ˌsɛnəˈzoʊɪk/) (meaning "new life" (Greek καινός (kainos), "new", and ζωή (zoe), "life"), is the most recent of the three classic geological eras and covers the period from 65.5 million years ago to the present. It is marked by the Cretaceous–Tertiary extinction event at the end of the Cretaceous that saw the demise of the last non-avian dinosaurs and the end of the Mesozoic Era. The Cenozoic era is ongoing.The Cenozoic Era is divided into two periods, the Tertiary (also sometimes referred to in terms of a Neogene Period or the Paleogene Period) , and Quaternary [4] . The Quaternary was officially recognized by the International Commission on Stratigraphy in June 2009.