Cenozoic Era

Cenozoic Era, third of the major eras of Earth’s history, beginning about 66 million years ago and extending to the present. It was the interval of time during which the continents assumed their modern configuration and geographic positions and during which Earth’s flora and fauna evolved toward those of the present.

geologic time

The term Cenozoic, originally spelled Kainozoic, was introduced by English geologist John Phillips in an 1840 Penny Cyclopaedia article to designate the most recent of the three major subdivisions of the Phanerozoic Eon. Derived from the Greek for recent life, it reflects the sequential development and diversification of life on Earth from the Paleozoic (ancient life) through the Mesozoic (middle life). Today, the Cenozoic is internationally accepted as the youngest of the three subdivisions of the fossiliferous part of Earth history.

The Cenozoic Era is generally divided into three periods: the Paleogene (66 million to 23 million years ago), the Neogene (23 million to 2.6 million years ago), and the Quaternary (2.6 million years ago to the present); however, the era has been traditionally divided into the Tertiary and Quaternary periods. The designations Tertiary and Quaternary, however, are relics of early attempts in the late 18th century at formulating a stratigraphic classification that included the now wholly obsolete terms Primary and Secondary. In 1856 Austrian geologist Moritz Hörnes introduced the terms Paleogene and Neogene, the latter encompassing rocks equivalent to those described by Scottish geologist Charles Lyell as Miocene and older and newer Pliocene (which included what he later called the Pleistocene). Subsequent investigators have determined that the designation Neogene correctly applies to the rock systems and corresponding time intervals delineated by Lyell, though some authorities prefer to exclude the Pleistocene from the Neogene. The Paleogene encompasses the Paleocene, Eocene, and Oligocene epochs. (The terms Paleocene and Oligocene were coined subsequent to Lyell’s work and inserted in the lower part of the Cenozoic stratigraphic scheme.) The Neogene spans the Miocene and Pliocene epochs, and the Quaternary includes the Pleistocene and Holocene epochs.