older of the two stratigraphic divisions of the Cenozoic Era spanning the interval between 65.5 million and 23 million years ago. Paleogene is Greek meaning “ancient-born” and includes the Paleocene (Paleocene Epoch) (Palaeocene) Epoch (65.5 million to 55.8 million years ago), the Eocene (Eocene Epoch) Epoch (55.8 million to 33.9 million years ago), and the Oligocene Epoch (33.9 million to 23 million years ago). The term Paleogene was devised in Europe to emphasize the similarity of marine fossils found in rocks of the first three Cenozoic epochs, as opposed to the later fossils of the Neogene Period (23 million years ago to the present). In North America, the Cenozoic has traditionally been divided only into the Tertiary Period (65.5 million to 2.6 million years ago) and the Quaternary Period (Quaternary) (2.6 million years ago to the present), but the designations Paleogene and Neogene are gaining more widespread usage.