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The Cenozoic Era (pronounced /ˌsiːnəˈzoʊɪk/, /ˌsɛn-/); sometimes Caenozoic Era or Cainozoic Era (in the United Kingdom), meaning "new life" (Greek καινός (kainos), "new", and ζωή (zoe), "life"), is the most recent of the three classic geological eras. It covers the 65.5 million years since the Cretaceous–Tertiary extinction event at the end of the Cretaceous that marked the demise of the last non-avian dinosaurs and the end of the Mesozoic Era. The Cenozoic era is ongoing.

The Cenozoic is divided into two periods, the Paleogene and Neogene, and they are in turn divided into epochs. The Paleogene consists of the Paleocene, Eocene, and Oligocene epochs, and the Neogene consists of the Miocene, Pliocene, Pleistocene, and Holocene epochs, the last of which is ongoing. Historically, the Cenozoic has been divided into periods (or sub-eras) named the Tertiary (Paleocene through Pliocene) and Quaternary (Pleistocene and Holocene).

Geologically, the Cenozoic is the era when continents moved into their current positions. Australia-New Guinea split from Gondwana and drifted north and, eventually, adjacent to South-east Asia; Antarctica moved into its current position over the South Pole; the Atlantic Ocean widened and, later in the era, South America became attached to North America.

The Cenozoic was a period of long-term cooling. In the early Cenozoic, particulate ejecta from the K-T boundary impact blocked incoming solar radiation^{[citation needed]}. After the tectonic creation of Drake Passage, and Australia fully detached from Antarctica in the Oligocene, the climate cooled significantly due to the advent of the Antarctic Circumpolar Current which brought cool deep Antarctic water to the surface. Warm conditions returned in the Miocene due to uncovered gas hydrates releasing carbon dioxide.^{[citation needed]} When South America became attached to North America creating the Isthmus of Panama, the Arctic region cooled due to the strengthening of the Humboldt and Gulf Stream currents^{[citation needed]}, eventually leading to the Last Glacial Maximum.

This short section requires expansion.

Mammals are the dominant creatures of Cenozoic.

The Cenozoic is the age of new life. During the Cenozoic, mammals diverged from a few small, simple, generalized forms into a diverse collection of terrestrial, marine, and flying animals. The Cenozoic is just as much the age of savannas, or the age of co-dependent flowering plants and insects. Birds also evolved substantially in the Cenozoic.

Monte Bolca is an important lagerstätte near Verona, Italy, containing excellently preserved fish and other fossils of Eocene age.

• Geologic Time Scale
• K-T Boundary

Wikimedia Commons has media related to:

Cenozoic

Wikisource has the text of the 1911 Encyclopædia Britannica article Cainozoic.

• British Caenozoic Fossils, 1975, The Natural History Museum, London.
• Geologic Time, by Henry Roberts.