Paleogene

First period of the Cenozoic Era

The Paleogene Period (IPA: PAY-lee-ə-jeen, -⁠lee-oh-, PAL-ee-; also spelled Palaeogene or Palæogene) is a geologic period and system that spans 43 million years from the end of the Cretaceous Period 66 Ma (million years ago) to the beginning of the Neogene Period 23.04 Ma. It is the first period of the Cenozoic Era, the tenth period of the Phanerozoic and is divided into the Paleocene, Eocene, and Oligocene epochs. The earlier term Tertiary Period was used to define the time now covered by the Paleogene and subsequent Neogene periods; despite no longer being recognized as a formal stratigraphic term, Tertiary sometimes remains in informal use.

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