​The Cenozoic Era is the current geolgoic era of the Phanerozoic Eon and extends from 65.5 Ma to the present. The Cenozoic Eon is divided into three geologic periods that include the Paleogene, Neogene and Quaternary. Cenozoic is derived from the Greek terms for recent cen and animal zo (Borror, 1988, pp. 23 & 111). The Cenozoic is best known for the appearance and diversification of modern mammal and bird orders. Grasslands first appear in the Cenozoic and greatly influenced the evolution of many mammals. Many flowering plants and insects evolved to be codependent. Humans first appear during the latter part of this Era.