|Nickname(s)||Age of Mammals|
K-Pg extinction event.
|Lower boundary GSSP||El Kef Section, El Kef, Tunisia|
36°09′13″N 8°38′55″E / 36.1537°N 8.6486°E
|Lower GSSP ratified||1991|
|Upper boundary definition||N/A|
|Upper boundary GSSP||N/A|
|Upper GSSP ratified||N/A|
The Cenozoic (
The Cenozoic is also known as the Age of Mammals because the terrestrial animals that dominated both hemispheres were mammals – the eutherians (placentals) in the northern hemisphere and the metatherians (marsupials, now mainly restricted to Australia and to some extent South America) in the southern hemisphere. The extinction of many groups allowed mammals and birds to greatly diversify so that large mammals and birds dominated life on Earth. The continents also moved into their current positions during this era.
The climate during the early Cenozoic was warmer than today, particularly during the Paleocene–Eocene Thermal Maximum. However, the Eocene to Oligocene transition and the Quaternary glaciation dried and cooled Earth.
Cenozoic derives from the Greek words kainós (καινός 'new') and zōḗ (ζωή 'life'). The name was proposed in 1840 by the British geologist John Phillips (1800–1874), who originally spelled it Kainozoic. The era is also known as the Cænozoic, Caenozoic, or Cainozoic (/ˌkaɪ.nəˈzoʊ.ɪk, ˌkeɪ-/).
In name, the Cenozoic (lit. 'new life') is comparable to the preceding Mesozoic ('middle life') and Paleozoic ('old life') Eras, as well as to the Proterozoic ('earlier life') Eon.
The Cenozoic is divided into three periods: the
The Paleogene spans from the extinction of non-avian dinosaurs, 66 million years ago, to the dawn of the Neogene, 23.03 million years ago. It features three
The Neogene spans from 23.03 million to 2.58 million years ago. It features 2 epochs: the Miocene, and the Pliocene.
India collided with Asia 55 to 45 million years ago creating the Himalayas; Arabia collided with Eurasia, closing the Tethys Ocean and creating the Zagros Mountains, around 35 million years ago.
The break-up of Gondwana in
In the Cretaceous, the climate was hot and humid with lush forests at the poles, there was no permanent ice and sea levels were around 300 metres higher than today. This continued for the first 10 million years of the Paleocene, culminating in the Paleocene–Eocene Thermal Maximum about 55.5 million years ago. Around 50 million years ago Earth entered a period of long term cooling. This was mainly due to the collision of India with Eurasia, which caused the rise of the Himalayas: the upraised rocks eroded and reacted with CO2 in the air, causing a long-term reduction in the proportion of this greenhouse gas in the atmosphere. Around 35 million years ago permanent ice began to build up on Antarctica. The cooling trend continued in the Miocene, with relatively short warmer periods. When South America became attached to North America creating the Isthmus of Panama around 2.8 million years ago, the Arctic region cooled due to the strengthening of the Humboldt and Gulf Stream currents, eventually leading to the glaciations of the Quaternary ice age, the current interglacial of which is the Holocene Epoch. Recent analysis of the geomagnetic reversal frequency, oxygen isotope record, and tectonic plate subduction rate, which are indicators of the changes in the heat flux at the core mantle boundary, climate and plate tectonic activity, shows that all these changes indicate similar rhythms on million years' timescale in the Cenozoic Era occurring with the common fundamental periodicity of ~13 Myr during most of the time.
Early in the Cenozoic, following the
During the Cenozoic,
In the earlier part of the Cenozoic, the world was dominated by the
The Cenozoic is full of mammals both strange and familiar, including
- ^ "Cenozoic". Lexico UK English Dictionary. Oxford University Press. Archived from the original on 23 November 2021.
- ^ "Cenozoic". Merriam-Webster Dictionary.
- ^ "Cenozoic". Online Etymology Dictionary.
- ^ Phillips, John (1840). "Palæozoic series". Penny Cyclopaedia of the Society for the Diffusion of Useful Knowledge. Vol. 17. London, England: Charles Knight and Co. pp. 153–154. From pp. 153–154: "As many systems or combinations of organic forms as are clearly traceable in the stratified crust of the globe, so many corresponding terms (as Palæozoic, Mesozoic, Kainozoic, &c.) may be made, ... "
- ^ Wilmarth, Mary Grace (1925). Bulletin 769: The Geologic Time Classification of the United States Geological Survey Compared With Other Classifications, accompanied by the original definitions of era, period and epoch terms. Washington, D.C., U.S.A.: U.S. Government Printing Office. p. 8.
- ^ The evolution of the spelling of "Cenozoic" is reviewed in:
- Harland, W. Brian; Armstrong, Richard L.; Cox, Allen V.; Craig, Lorraine E.; Smith, David G.; Smith, Alan G. (1990). "The Chronostratic Scale". A Geologic Time Scale 1989. Cambridge, England, U.K.: Cambridge University Press. p. 31. ISBN 9780521387651.
- Phillips, John (1841). Figures and Descriptions of the Palæozoic Fossils of Cornwall, Devon, and West Somerset; ... London, England, U.K.: Longman, Brown, Green, & Longmans. p. 160.
- Harland, W. Brian; Armstrong, Richard L.; Cox, Allen V.; Craig, Lorraine E.; Smith, David G.; Smith, Alan G. (1990). "The Chronostratic Scale". A Geologic Time Scale 1989. Cambridge, England, U.K.: Cambridge University Press. p. 31.
- ^ "Cainozoic". Dictionary.com Unabridged (Online). n.d.
- ^ "Cainozoic". Oxford English Dictionary (2nd ed.). 1989.
- S2CID 206544776.
- S2CID 130110536.
- S2CID 11207255.
- ^ Royal Tyrrell Museum (28 March 2012), Lamniform sharks: 110 million years of ocean supremacy, archived from the original on 7 August 2013, retrieved 12 July 2017
- ^ University of California. "Eocene Epoch". University of California.
- S2CID 205248384. Retrieved 19 January 2023.
- ^ University of California. "Eocene Climate". University of California.
- ^ National Geographic Society (24 January 2017). "Eocene". National Geographic.
- ^ University of California. "Oligocene". University of California.
- ^ "Neogene". Encyclopædia Britannica.
- ^ University of California. "Miocene". University of California.
- ^ University of California. "Pliocene". University of California.
- ^ Jonathan Adams. "Pliocene climate". Oak Ridge National Library. Archived from the original on 25 February 2015.
- ^ University of California. "Pleistocene". University of California. Archived from the original on 24 August 2014. Retrieved 25 April 2015.
- ^ University of California. "Holocene". University of California.
- ^ "Sixth Extinction extinctions". Scientific American.
- ^ IUCN (3 November 2009). "Sixth Extinction". IUCN.
- PMID 26601195.
- ISBN 978-1-8479-2435-3.
- ^ "How the Isthmus of Panama Put Ice in the Arctic". Oceanus Magazine.
- ^ "The Cenozoic Era". ucmp.berkeley.edu.
- Prothero, Donald R. (2006). After the Dinosaurs: The Age of Mammals. Bloomington, Indiana: Indiana University Press. ISBN 978-0-253-34733-6.