The Cenozoic (also Caenozoic or Cainozoic) Era (meaning "new life" (Greek καινός (kainos), "new", and ζωή (zoe), "life"), is the most recent of the three classic geological eras and covers the period from 65.5 million years ago to the present. It is marked by the Cretaceous–Tertiary extinction event at the end of the Cretaceous that saw the demise of the last non-avian dinosaurs and the end of the Mesozoic Era. The Cenozoic era is ongoing.
The Cenozoic Era is divided into two periods, the Paleogene
, and they are in turn divided into epochs
. The Paleogene consists of the Paleocene
, and Oligocene
epochs, and the Neogene consists of the Miocene
, 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).
, the Cenozoic is the era when the continents
moved into their current positions. Australia-New Guinea
split from Gondwana
and drifted north and, eventually, adjacent to South-east Asia
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
India collided with Asia between 55 and 45 million years ago; Arabia collided with Eurasia, closing the Tethys ocean, around .
The Cenozoic Era has been a period of long-term cooling. In the early Cenozoic, particulate ejecta from the K-T boundary
impact blocked incoming solar radiation . After the tectonic creation of Drake Passage
, when Australia fully detached from Antarctica during 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
. 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, eventually leading to the Last Glacial Maximum
The Cenozoic Era 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.
- British Caenozoic Fossils, 1975, The Natural History Museum, London.
- Geologic Time, by Henry Roberts.