View source for Cenozoic

{{Short description|Third era of the Phanerozoic Eon}}
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{{Infobox geologic timespan
| name                         = Cenozoic
| color                        = Cenozoic
| top_bar                      = phanerozoic
| time_start                   = 66.0
| time_end                     = 0
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| image_outcrop                = File:Torre Sant'Andrea.jpg
| caption_outcrop              = Rock deposits from the Cenozoic Era ([[Torre Sant'Andrea]], [[Salento]], [[Italy]])<ref name="SAndrea_GeolMap">{{Cite map |year=1968 |title =Gallipoli |scale = 1:100,000 |publisher=Dipartimento per il Servizio Geologico d'Italia |series=Carta Geologica d'Italia (Scala 1:100.000) |edition=2nd |sheet=:Foglio 214 |url=https://sgi.isprambiente.it/geologia100k/mostra_foglio.aspx?numero_foglio=214 |access-date=31 May 2025}}</ref>
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| timeline                     = Cenozoic
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<!--Etymology-->
| name_formality               = Formal
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| nicknames                    = Age of Mammals
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<!--Usage Information--> 
| celestial_body               = Earth
| usage                        = Global ([[International Commission on Stratigraphy|ICS]])
| timescales_used              = ICS Time Scale
| formerly_used_by             =
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<!--Definition-->
| chrono_unit                  = Era
| strat_unit                   = Erathem
| proposed_by                  =
| timespan_formality           = Formal
| lower_boundary_def           = [[Iridium]] enriched layer associated with a major meteorite impact and subsequent [[K-Pg extinction event]].
| lower_gssp_location          = El Kef Section, [[El Kef]], [[Tunisia]]
| lower_gssp_coords            = {{Coord|36.1537|N|8.6486|E|display=inline}}
| lower_gssp_accept_date       = 1991
| upper_boundary_def           = N/A
| upper_gssp_location          = N/A
| upper_gssp_accept_date       = N/A
}}
The '''Cenozoic Era''' (also known as '''Caenozoic''', '''Kainozoic''' or '''Neozoic''' Era) ({{IPAc-en|ˌ|s|iː|n|ə|ˈ|z|oʊ|.|ɪ|k|,_|ˌ|s|ɛ|n|-|}} {{respell|SEE|nə|ZOH|ik|,_|SEN|ə|-}};{{refn|{{Cite dictionary |url=http://www.lexico.com/definition/Cenozoic |archive-url=https://web.archive.org/web/20211123175940/https://www.lexico.com/definition/Cenozoic |archive-date=23 November 2021 |title=Cenozoic |dictionary=[[Lexico]] UK English Dictionary |publisher=[[Oxford University Press]]}} }}{{refn|{{MW|Cenozoic}}}} {{lit|new life}}) is Earth's current geological [[Era (geology)|era]], representing the last 66{{nbsp}}million years of Earth's history. It is characterized by the dominance of  [[mammal]]s, [[Insect|insects]], [[bird]]s and [[flowering plant|angiosperm]]s (flowering plants). It is the latest of three geological eras of the [[Phanerozoic]] [[Eon (geology)|Eon]], preceded by the [[Mesozoic]] and [[Paleozoic]]. The Cenozoic started with the [[Cretaceous–Paleogene extinction event]], when many species, including the non-avian [[dinosaurs]], became extinct in an event attributed by most experts to the impact of a large asteroid or other celestial body, the [[Chicxulub impactor]].

The Cenozoic is also known as the '''Age of Mammals''' because the terrestrial animals that dominated both hemispheres were mammals{{snds}}the [[eutheria]]ns ([[placental]]s) in the Northern Hemisphere and the [[metatheria]]ns ([[marsupial]]s, 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.

==Nomenclature==
{{wikt|Cenozoic|Caenozoic}}
''Cenozoic'' derives from the [[Ancient Greek]] words {{lang|grc-Latn|kainós}} ({{wikt-lang|grc|καινός}}, 'new') and {{lang|grc-Latn|zōḗ}} ({{wikt-lang|grc|ζωή}}, 'life').<ref name="OnlineEtymologyDict">{{cite dictionary|title=Cenozoic|url=http://www.etymonline.com/index.php?term=Cenozoic&allowed_in_frame=0|dictionary=[[Online Etymology Dictionary]]}}</ref> The name was proposed in 1840 by the British geologist [[John Phillips (geologist)|John Phillips]] (1800–1874), who originally spelled it ''Kainozoic''.<ref>{{cite book |last1=Phillips |first1=John |title=Penny Cyclopaedia of the Society for the Diffusion of Useful Knowledge |volume= 17 |date=1840 |publisher=Charles Knight and Co. |location=London, England |pages=153–154 |chapter-url=https://babel.hathitrust.org/cgi/pt?id=hvd.hn4zr7;view=1up;seq=163 |chapter=Palæozoic series}}  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, ... "</ref><ref>{{cite book |last1=Wilmarth |first1=Mary Grace |title=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 |date=1925 |publisher=U.S. Government Printing Office |location=Washington, D.C., U.S. |page=8 |url=https://books.google.com/books?id=my7x_PBkpm4C&pg=PA8}}</ref><ref>The evolution of the spelling of "Cenozoic" is reviewed in: 
* {{cite book |last1=Harland |first1=W. Brian |last2=Armstrong |first2=Richard L. |last3=Cox |first3=Allen V. |last4=Craig |first4=Lorraine E. |last5=Smith |first5=David G. |last6=Smith |first6=Alan G. |title=A Geologic Time Scale 1989 |date=1990 |publisher=Cambridge University Press |location=Cambridge, England, U.K. |page=31 |chapter-url=https://books.google.com/books?id=xbKJV6LSeggC&pg=PA31 |chapter=The Chronostratic Scale|isbn=978-0-521-38765-1 }}
Although John Phillips originally spelled it as "Kainozoic" in 1840, he spelled it "Cainozoic" a year later:
* {{cite book |last1=Phillips |first1=John |title=Figures and Descriptions of the Palæozoic Fossils of Cornwall, Devon, and West Somerset; ... |date=1841 |publisher=Longman, Brown, Green, & Longmans |location=London, England, U.K. |page=[https://archive.org/details/figuresanddescr00philgoog/page/n174 160] |url=https://archive.org/details/figuresanddescr00philgoog}}</ref> The era is also known as the ''Cænozoic'', ''Caenozoic'', or ''Cainozoic'' ({{IPAc-en|ˌ|k|aɪ|.|n|ə|ˈ|z|oʊ|.|ɪ|k|,_|ˌ|k|eɪ|-}}).{{refn|{{cite Dictionary.com|Cainozoic}}}}<ref>{{cite encyclopedia |title=Cainozoic |encyclopedia=[[Oxford English Dictionary]] |edition=2nd |year=1989}}</ref>

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.

==Divisions==
The Cenozoic is divided into three periods: the [[Paleogene]], [[Neogene]], and [[Quaternary]]; and seven [[Epoch (geology)|epoch]]s: the [[Paleocene]], [[Eocene]], [[Oligocene]], [[Miocene]], [[Pliocene]], [[Pleistocene]], and [[Holocene]]. The Quaternary Period was officially recognised by the [[International Commission on Stratigraphy]] in June 2009.<ref name="Gibbard-2010">{{cite journal | year = 2010 | last1 = Gibbard | first1 = P. L. | last2 = Head | first2 = M. J. | last3 = Walker | first3 = M. J. C. | title = Formal ratification of the Quaternary System/Period and the Pleistocene Series/Epoch with a base at 2.58 Ma | journal = Journal of Quaternary Science | volume = 25 | issue = 2 | pages = 96–102 | bibcode = 2010JQS....25...96G | doi = 10.1002/jqs.1338| doi-access = free }}</ref> In 2004, the [[Tertiary Period]] was officially replaced by the Paleogene and Neogene Periods. The common use of epochs during the Cenozoic helps [[palaeontologist]]s better organise and group the many significant events that occurred during this comparatively short interval of time. Knowledge of this era is more detailed than any other era because of the relatively young, well-preserved rocks associated with it.

===Paleogene===
The [[Paleogene]] spans from the extinction of non-avian dinosaurs, 66 million years ago, to the dawn of the Neogene, 23.03&nbsp;million years ago. It features three [[epoch (geology)|epoch]]s: the [[Paleocene]], [[Eocene]] and [[Oligocene]].  [[File:Basilosaurus.jpg|thumb|left|''[[Basilosaurus]]'']]

The [[Paleocene Epoch]] lasted from 66 million to 56&nbsp;million years ago. Modern placental mammals originated during this time.<ref name="O'Leary-2013">{{cite journal |last1=O'Leary |first1=Maureen A. |last2=Bloch |first2=Jonathan I. |last3=Flynn |first3=John J. |last4=Gaudin |first4=Timothy J. |last5=Giallombardo |first5=Andres |last6=Giannini |first6=Norberto P. |last7=Goldberg |first7=Suzann L. |last8=Kraatz |first8=Brian P. |last9=Luo |first9=Zhe-Xi |last10=Meng |first10=Jin |last11=Ni |first11=Michael J. |last12=Novacek |first12=Fernando A. |last13=Perini |first13=Zachary S. |last14=Randall |first14=Guillermo |last15=Rougier |first15=Eric J. |last16=Sargis |first16=Mary T. |last17=Silcox |first17=Nancy b. |last18=Simmons |first18=Micelle |last19=Spaulding |first19=Paul M. |last20=Velazco |first20=Marcelo |last21=Weksler |first21=John r. |last22=Wible |first22=Andrea L. |title=The Placental Mammal Ancestor and the Post–K-Pg Radiation of Placentals |date=8 February 2013 |journal=[[Science (journal)|Science]] |volume=339 |pages=662–667 |doi=10.1126/science.1229237 |pmid=23393258 |issue=6120 |last23=Cirranello |first23=A. L. |bibcode=2013Sci...339..662O |hdl=11336/7302 |s2cid=206544776 |hdl-access=free }}</ref> The devastation of the [[K–Pg extinction event]] included the extinction of large [[Herbivore|herbivores]], which permitted the spread of dense but usually species-poor forests.<ref name="Williams-2009">{{cite journal|first1=C. J.|last1=Williams|first2=B. A.|last2=LePage|first3=A. H.|last3=Johnson|first4=D. R.|last4=Vann|year=2009|title=Structure, Biomass, and Productivity of a Late Paleocene Arctic Forest|journal= Proceedings of the Academy of Natural Sciences of Philadelphia|volume=158|issue=1|pages=107–127|doi=10.1635/053.158.0106|bibcode=2009PANSP.158..107W |s2cid=130110536}}</ref><ref>{{cite journal |last1=Johnson |first1=Kirk R. |last2=Ellis |first2=Beth |title=A Tropical Rainforest in Colorado 1.4 Million Years After the Cretaceous-Tertiary Boundary |journal=Science |date=28 June 2002 |volume=296 |issue=5577 |pages=2379–2383 |doi=10.1126/science.1072102|pmid=12089439 |bibcode=2002Sci...296.2379J |s2cid=11207255 }}</ref> The Early Paleocene saw the recovery of Earth. The continents began to take their modern shape, but all the continents and the subcontinent of India were separated from each other. [[Afro-Eurasia]] was separated by the [[Tethys Sea]], and the Americas were separated by the strait of Panama, as the [[Isthmus of Panama|isthmus]] had not yet formed. This epoch featured a general warming trend, with jungles eventually reaching the poles. The oceans were dominated by sharks<ref>{{Citation|last=Royal Tyrrell Museum|title=Lamniform sharks: 110 million years of ocean supremacy|date=28 March 2012|url=https://www.youtube.com/watch?v=e4p9EWuVxYQ| archive-url=https://web.archive.org/web/20130807114000/http://www.youtube.com/watch?v=e4p9EWuVxYQ&gl=US&hl=en| archive-date=7 August 2013 |access-date=12 July 2017}}</ref> as the large reptiles that had once predominated were extinct. Archaic mammals filled the world such as [[creodonts]] (extinct carnivores, unrelated to existing [[Carnivora]]).

The [[Eocene Epoch]] ranged from 56 million years to 33.9&nbsp;million years ago. In the Early-Eocene, species living in dense forest were unable to evolve into larger forms, as in the Paleocene. Among them were early primates, whales and horses along with many other early forms of mammals. At the top of the food chains were huge birds, such as [[Paracrax]]. Carbon dioxide levels were approximately 1,400 [[Parts per million|ppm]].<ref>{{cite journal |last1=Anagnostou |first1=Eleni |last2=John |first2=Eleanor H. |last3=Edgar |first3=Kirsty M. |last4=Foster |first4=Gavin L. |last5=Ridgwell |first5=Andy |last6=Inglis |first6=Gordon N. |last7=Pancost |first7=Richard D. |last8=Lunt |first8=Daniel J. |last9=Pearson |first9=Paul N. |date=25 April 2016 |title=Changing atmospheric CO2 concentration was the primary driver of early Cenozoic climate |url=https://www.nature.com/articles/nature17423?error=cookies_not_supported&code=0e2a9a94-0fff-4718-853e-0a344e2fa5d0 |journal=[[Nature (journal)|Nature]] |volume=533 |issue=7603 |pages=380–384 |doi=10.1038/nature17423 |pmid=27111509 |s2cid=205248384 |access-date=19 January 2023|hdl=1983/799fc7ff-ff17-41b7-8dcc-cae1b66c5734 |hdl-access=free |url-access=subscription }}</ref> The temperature was 30 degrees Celsius with little temperature gradient from pole to pole. In the Mid-Eocene, the [[Antarctic Circumpolar Current]] between Australia and Antarctica formed. This disrupted ocean currents worldwide and as a result caused a global cooling effect, shrinking the jungles. This allowed mammals to grow to mammoth proportions, such as whales which, by that time, had become almost fully aquatic. Mammals like ''[[Andrewsarchus]]'' were at the top of the food-chain. The Late Eocene saw the rebirth of seasons, which caused the expansion of savanna-like areas, along with the evolution of [[grasses]].<ref>{{cite web|url=http://www.ucmp.berkeley.edu/tertiary/eocene.php|title=Eocene Climate|author=University of California|work=University of California}}</ref><ref>{{cite web|url=http://science.nationalgeographic.com/science/prehistoric-world/paleogene/|archive-url=https://web.archive.org/web/20100508003008/http://science.nationalgeographic.com/science/prehistoric-world/paleogene/|archive-date=8 May 2010|title=Eocene|author=National Geographic Society|work=National Geographic|date=24 January 2017}}</ref> The end of the Eocene was marked by the [[Eocene–Oligocene extinction event]],<ref>{{cite journal |last1=Retallack |first1=Gregory J. |last2=Orr |first2=William N. |last3=Prothero |first3=Donald Ross |last4=Duncan |first4=Robert A. |last5=Kester |first5=Paul R. |last6=Ambers |first6=Clifford P. |date=1 July 2004 |title=Eocene–Oligocene extinction and paleoclimatic change near Eugene, Oregon |url=https://pubs.geoscienceworld.org/gsa/gsabulletin/article-abstract/116/7-8/817/2099/Eocene-Oligocene-extinction-and-paleoclimatic |journal=[[Geological Society of America Bulletin]] |volume=116 |issue=7–8 |pages=817–839 |doi=10.1130/B25281.1 |bibcode=2004GSAB..116..817R |access-date=16 April 2023|url-access=subscription }}</ref><ref>{{cite journal |last1=Prothero |first1=Donald Ross |title=The Late Eocene-Oligocene Extinctions |date=May 1994 |url=https://www.annualreviews.org/doi/abs/10.1146/annurev.ea.22.050194.001045?journalCode=earth |journal=[[Annual Review of Earth and Planetary Sciences]] |volume=22 |pages=145–165 |doi=10.1146/annurev.ea.22.050194.001045 |bibcode=1994AREPS..22..145P |access-date=16 April 2023|url-access=subscription }}</ref><ref name="Ivany-2000">{{Cite journal |last1=Ivany |first1=Linda C. |last2=Patterson |first2=William P. |last3=Lohmann |first3=Kyger C. |title=Cooler winters as a possible cause of mass extinctions at the Eocene/Oligocene boundary |journal=[[Nature (journal)|Nature]] |volume=407 |issue=6806 |pages=887–890 |doi=10.1038/35038044|pmid=11057663|year=2000|hdl=2027.42/62707 |url=https://deepblue.lib.umich.edu/bitstream/2027.42/62707/1/407887a0.pdf |bibcode=2000Natur.407..887I |s2cid=4408282 |hdl-access=free}}</ref> the European face of which is known as the [[Grande Coupure]].<ref>{{cite journal |last1=Zhang |first1=R. |last2=Kravchinsky |first2=V.A. |last3=Yue |first3=L. |date=21 May 2012 |title=Link between Global Cooling and Mammalian Transformation across the Eocene–Oligocene Boundary in the Continental Interior of Asia |url=https://link.springer.com/article/10.1007/s00531-012-0776-1 |journal=[[International Journal of Earth Sciences]] |volume=101 |issue=8 |pages=2193–2200 |doi=10.1007/s00531-012-0776-1 |bibcode=2012IJEaS.101.2193Z |s2cid=55409146 |access-date=4 August 2023 |url-access=subscription }}</ref><ref>{{Cite journal |pmid=10588762 |date=December 1999 |author1=Köhler, M |author2=Moyà-Solà, S |title=A finding of Oligocene primates on the European continent |url=https://www.researchgate.net/publication/12712095 |volume=96 |issue=25 |pages=14664–7 |issn=0027-8424 |pmc=24493 |journal=[[Proceedings of the National Academy of Sciences of the United States of America]] |doi=10.1073/pnas.96.25.14664 |bibcode=1999PNAS...9614664K |doi-access=free |access-date=28 July 2023}}</ref>

The [[Oligocene]] spans from 33.9&nbsp;million to 23.03&nbsp;million years ago. The Oligocene featured the expansion of grasslands which had led to many new species to evolve, including the first elephants, cats, dogs, marsupials and many other species still prevalent today. Many other species of plants evolved in this period too. A cooling period featuring seasonal rains was still in effect. Mammals still continued to grow larger and larger.<ref>{{cite web|url=http://www.ucmp.berkeley.edu/tertiary/oligocene.php|title=Oligocene|author=University of California|work=University of California}}</ref>

===Neogene===
The [[Neogene]] spans from 23.03&nbsp;million to 2.58&nbsp;million years ago.  It features two epochs: the Miocene, and the Pliocene.<ref>{{cite encyclopedia|url=https://www.britannica.com/EBchecked/topic/408872/Neogene-Period|title=Neogene|encyclopedia=Encyclopædia Britannica|date=9 August 2024 }}</ref>

The [[Miocene Epoch]] spans from 23.03 to 5.333&nbsp;million years ago and is a period in which [[grasses]] spread further, dominating a large portion of the world, at the expense of forests. [[Kelp]] forests evolved, encouraging the evolution of new species, such as [[sea otter]]s. During this time, [[Perissodactyla]] thrived, and evolved into many different varieties. [[Apes]] evolved into 30 species. The [[Tethys Sea]] finally closed with the creation of the [[Arabian Peninsula]], leaving only remnants as the [[Black Sea|Black]], [[Red Sea|Red]], [[Mediterranean Sea|Mediterranean]] and [[Caspian Sea]]s. This increased aridity. Many new plants evolved: 95% of modern [[Spermatophyte|seed plants]] families were present by the end of the Miocene.<ref>{{cite web|url=http://www.ucmp.berkeley.edu/tertiary/miocene.php|title=Miocene|author=University of California|work=University of California}}</ref>

The [[Pliocene Epoch]] lasted from 5.333 to 2.58&nbsp;million years ago. The Pliocene featured dramatic climatic changes, which ultimately led to modern species of flora and fauna. The Mediterranean Sea dried up for several million years (because the [[ice age]]s reduced sea levels, disconnecting the [[Atlantic Ocean|Atlantic]] from the Mediterranean, and evaporation rates exceeded inflow from rivers). ''[[Australopithecus]]'' evolved in [[Africa]], beginning the human branch. The [[Isthmus of Panama]] formed, and animals migrated between [[North America|North]] and [[South America]] during the [[great American interchange]], wreaking havoc on local ecologies. Climatic changes brought: [[savanna]]s that are still continuing to spread across the world; Indian [[monsoon]]s; [[desert]]s in central [[Asia]]; and the beginnings of the [[Sahara]] desert. The world map has not changed much since, save for changes brought about by the [[glaciations]] of the Quaternary, such as the [[Great Lakes]], [[Hudson Bay]], and the [[Baltic Sea]].<ref>{{cite web|url=http://www.ucmp.berkeley.edu/tertiary/pliocene.php|title=Pliocene|author=University of California|work=University of California}}</ref><ref>{{cite web|url=http://www.esd.ornl.gov/projects/qen/pliocene.html|title=Pliocene climate|first=Jonathan |last=Adams|work=Oak Ridge National Library|archive-url=https://web.archive.org/web/20150225011508/http://www.esd.ornl.gov/projects/qen/pliocene.html|archive-date=25 February 2015}}</ref>

===Quaternary===
The [[Quaternary]] spans from 2.58&nbsp;million years ago to present day, and is the shortest geological period in the [[Phanerozoic Eon]]. It features modern animals, and dramatic changes in the climate. It is divided into two epochs: the Pleistocene and the Holocene.

[[File:Ice age fauna of northern Spain - Mauricio Antón.jpg|thumb|Megafauna of Pleistocene Europe ([[mammoth]]s, [[Panthera spelaea|cave lions]], [[woolly rhino]], [[reindeer]], [[Wild horse|horses]])]]
The [[Pleistocene]] lasted from 2.58&nbsp;million to 11,700 years ago. This epoch was marked by [[ice ages]] as a result of the cooling trend that started in the Mid-Eocene. There were at least four separate glaciation periods marked by the advance of ice caps as far south as 40° N in mountainous areas. Meanwhile, Africa experienced a trend of [[desiccation]] which resulted in the creation of the [[Sahara desert|Sahara]], [[Namib Desert|Namib]], and [[Kalahari Desert|Kalahari]] deserts. Many animals evolved including [[mammoth]]s, [[giant ground sloths]], [[dire wolves]], sabre-toothed cats, and ''[[Homo sapiens]]''. 100,000 years ago marked the end of one of the worst droughts in Africa, and led to the expansion of primitive humans. As the Pleistocene drew to a close, a major extinction wiped out much of the world's megafauna, including some of the hominid species, such as [[Neanderthal]]s. All the continents were affected, but Africa to a lesser extent. It still retains many large animals, such as hippos.<ref>{{cite web|url=http://www.ucmp.berkeley.edu/quaternary/pleistocene.php|title=Pleistocene|author=University of California|work=University of California|access-date=25 April 2015|archive-url=https://web.archive.org/web/20140824111711/http://www.ucmp.berkeley.edu/quaternary/pleistocene.php|archive-date=24 August 2014}}</ref>

The [[Holocene]] began 11,700 years ago and lasts to the present day. All recorded history and "the [[Human history]]" lies within the boundaries of the Holocene Epoch.<ref>{{cite web|url=http://www.ucmp.berkeley.edu/quaternary/holocene.php|title=Holocene|author=University of California|work=University of California}}</ref> Human activity is blamed for a mass extinction that began roughly 10,000 years ago, though the species becoming extinct have only been recorded since the [[Industrial Revolution]]. This is sometimes referred to as the "[[Sixth Extinction]]". It is often cited that over 322 recorded species have become extinct due to human activity since the Industrial Revolution,<ref>{{cite web|url=http://www.scientificamerican.com/article/fact-or-fiction-the-sixth-mass-extinction-can-be-stopped/|title=Sixth Extinction extinctions|work=Scientific American}}</ref><ref>{{cite web|url=http://www.iucn.org/?4143/Extinction-crisis-continues-apace|title=Sixth Extinction|author=IUCN|work=IUCN|date=3 November 2009}}</ref> but the rate may be as high as 500 vertebrate species alone, the majority of which have occurred after 1900.<ref>{{cite journal|title=Accelerated modern human–induced species losses: Entering the sixth mass extinction|author=Ceballos et al. (2015)|volume=1|issue=5|article-number=e1400253|journal=Science Advances|pmid=26601195|year=2015|doi=10.1126/sciadv.1400253|pmc=4640606|bibcode=2015SciA....1E0253C}}</ref>

==Tectonics==
[[Geology|Geologically]], the Cenozoic is the era when the [[continent]]s moved into their current positions. [[Australia (continent)|Australia-New Guinea]], having split from [[Pangea]] during the early [[Cretaceous]], drifted north and, eventually, collided with [[South-east Asia|Southeast Asia]]; [[Antarctica]] moved into its current position over the [[South Pole]]; the [[Atlantic Ocean]] widened and, later in the era (2.8&nbsp;million years ago), [[South America]] became attached to [[North America]] with the [[isthmus of Panama]].

India collided with Asia {{Ma|55|45}} creating the Himalayas; Arabia collided with Eurasia, closing the [[Tethys Ocean]] and creating the [[Zagros Mountains]], around {{Ma|35}}.<ref name="Allen-2008">{{cite journal| first1 = M. B.| first2 = H. A. | title = Arabia-Eurasia collision and the forcing of mid Cenozoic global cooling| last2 = Armstrong  | url =  http://dro.dur.ac.uk/14557/1/14557.pdf| journal = Palaeogeography, Palaeoclimatology, Palaeoecology | volume = 265 | issue = 1–2| pages = 52–58 | year = 2008| last1 = Allen | doi = 10.1016/j.palaeo.2008.04.021 | bibcode = 2008PPP...265...52A }}</ref>

The break-up of Gondwana in [[Late Cretaceous]] and Cenozoic times led to a shift in the river courses of various large African rivers including the [[Congo River|Congo]], [[Niger River|Niger]], [[Nile]], [[Orange River|Orange]], [[Limpopo River|Limpopo]] and [[Zambezi River|Zambezi]].<ref>{{cite journal |last1=Goudie |first1=A.S.|author-link=Andrew Goudie (geographer) |year=2005 |title=The drainage of Africa since the Cretaceous |journal=[[Geomorphology (journal)|Geomorphology]] |volume=67 |issue= 3–4|pages=437–456 |doi= 10.1016/j.geomorph.2004.11.008|bibcode=2005Geomo..67..437G}}</ref>

==Climate==
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&nbsp;million years of the Paleocene, culminating in the [[Paleocene–Eocene Thermal Maximum]] about {{Ma|55.5}}. Around {{Ma|50}}, 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 {{Ma|35}}, permanent ice began to build up on Antarctica.<ref>{{cite book|last=Dartnell |first=Lewis |author-link=Lewis Dartnell |title=Origins:How the Earth Made Us |publisher=Bodley Head |location =London, UK|pages=9–10, 40 |year=2018|isbn=978-1-8479-2435-3 }}</ref> 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 {{Ma|2.8}}, the Arctic region cooled due to the strengthening of the [[Humboldt Current|Humboldt]] and [[Gulf Stream]] currents,<ref>{{cite web|url=http://www.whoi.edu/oceanus/viewArticle.do?id=2508|title=How the Isthmus of Panama Put Ice in the Arctic|work=Oceanus Magazine}}</ref> eventually leading to the glaciations of the [[Quaternary glaciation|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.<ref>{{cite journal | last1 = Chen | first1 = J. | last2 = Kravchinsky | first2 = V.A. | last3 = Liu | first3 = X. | year = 2015 | title = The 13 million year Cenozoic pulse of the Earth | journal = Earth and Planetary Science Letters | volume = 431 | pages = 256–263 | doi = 10.1016/j.epsl.2015.09.033 | bibcode=2015E&PSL.431..256C}}</ref> The levels of carbonate ions in the ocean fell over the course of the Cenozoic.<ref>{{Cite journal |last1=Boudreau |first1=Bernard P. |last2=Luo |first2=Yiming |date=15 September 2017 |title=Retrodiction of secular variations in deep-sea CaCO3 burial during the Cenozoic |journal=[[Earth and Planetary Science Letters]] |volume=474 |pages=1–12 |doi=10.1016/j.epsl.2017.06.005 |issn=0012-821X |doi-access=free }}</ref>

==Life==
[[File:Paleotherium magnum.jpg|thumb|left|Restoration of ''[[Palaeotherium]]'', a [[Paleogene]] relative of horses that lived in subtropical climates of Europe during the [[Eocene]]]]
Early in the Cenozoic, following the [[Cretaceous-Paleogene Extinction Event|K-Pg event]], the planet was dominated by relatively small fauna, including small mammals, birds, reptiles, and amphibians. From a geological perspective, it did not take long for mammals to greatly diversify in the absence of the dinosaurs that had dominated during the Mesozoic.<ref>{{Cite journal |last1=Shupinski |first1=Alex B. |last2=Wagner |first2=Peter J. |last3=Smith |first3=Felisa A. |last4=Lyons |first4=S. Kathleen |date=3 July 2024 |title=Unique functional diversity during early Cenozoic mammal radiation of North America |journal=[[Proceedings of the Royal Society B: Biological Sciences]] |language=en |volume=291 |issue=2026 |article-number=20240778 |doi=10.1098/rspb.2024.0778 |issn=1471-2954 |pmc=11286128 |pmid=38955231 }}</ref> Birds also diversified rapidly; some flightless birds grew larger than humans. These species are sometimes referred to as "[[terror bird]]s", and were formidable predators. Mammals came to occupy almost every available [[ecological niche|niche]] (both marine and [[terrestrial animal|terrestrial]]), and some also grew very large, attaining sizes not seen in most of today's terrestrial mammals. The ranges of many Cenozoic bird clades were governed by latitude and temperature and have contracted over the course of this era as the world cooled.<ref>{{cite journal |last1=Saupe |first1=Erin E. |last2=Farnsworth |first2=Alexander |last3=Lunt |first3=Daniel J. |last4=Sagoo |first4=Navjit |last5=Pham |first5=Karen V. |last6=Field |first6=Daniel J. |date=10 June 2019 |title=Climatic shifts drove major contractions in avian latitudinal distributions throughout the Cenozoic |journal= Proceedings of the National Academy of Sciences|volume=116 |issue=26 |pages=12895–12900 |doi=10.1073/pnas.1903866116 |pmid=31182570 |pmc=6601418 |doi-access=free |bibcode=2019PNAS..11612895S }}</ref>

During the Cenozoic, [[Mammal evolution#Expansion of ecological niches in the Mesozoic|mammals proliferated]] from a few small, simple, generalised forms into a diverse collection of [[Terrestrial animal|terrestrial]], [[Marine mammal|marine]], and [[bat|flying]] animals, giving this period its other name, the Age of Mammals. The Cenozoic is just as much the age of [[savanna]]s, the age of co-dependent [[flowering plant]]s and [[insect]]s, and the age of birds.<ref>{{Cite web|url=https://ucmp.berkeley.edu/cenozoic/cenozoic.php|title=The Cenozoic Era|website=ucmp.berkeley.edu}}</ref> [[Grasses]] also played a very important role in this era, shaping the evolution of the birds and mammals that fed on them.  One group that diversified significantly in the Cenozoic as well were the [[snake]]s. Evolving in the Cenozoic, the variety of snakes increased tremendously, resulting in many [[colubrids]], following the evolution of their current primary prey source, the [[rodent]]s.

In the earlier part of the Cenozoic, the world was dominated by the [[Gastornithidae|gastornithid]] birds, terrestrial [[crocodylian]]s like ''[[Pristichampsus]]'', large sharks such as [[Otodus]], and a handful of primitive large mammal groups like [[uintathere]]s, [[Mesonychia|mesonychians]], and [[pantodont]]s. But as the forests began to recede and the climate began to cool, other mammals took over.

The Cenozoic is full of mammals both strange and familiar, including [[chalicothere]]s, [[creodont]]s, [[whale]]s, [[primate]]s, [[entelodont]]s, [[sabre-toothed cat]]s, [[mastodon]]s and [[mammoth]]s, [[three-toed horse]]s, giant [[rhinoceros]] like ''[[Paraceratherium]]'', the rhinoceros-like [[brontothere]]s, various bizarre groups of mammals from South America, such as the vaguely elephant-like [[pyrotheria|pyrothere]]s and the dog-like marsupial relatives called [[borhyaenidae|borhyaenids]] and the [[monotreme]]s and marsupials of Australia. Mammal evolution in the Cenozoic was predominantly shaped by climatic and geological processes.<ref>{{Cite journal |last1=Feijó |first1=Anderson |last2=Ge |first2=Deyan |last3=Wen |first3=Zhixin |last4=Cheng |first4=Jilong |last5=Xia |first5=Lin |last6=Patterson |first6=Bruce D. |last7=Yang |first7=Qisen |date=6 December 2022 |title=Mammalian diversification bursts and biotic turnovers are synchronous with Cenozoic geoclimatic events in Asia |journal=[[Proceedings of the National Academy of Sciences of the United States of America]] |language=en |volume=119 |issue=49 |article-number=e2207845119 |doi=10.1073/pnas.2207845119 |doi-access=free |issn=0027-8424 |pmc=9894185 |pmid=36442115 |bibcode=2022PNAS..11907845F }}</ref><ref>{{Cite journal |last1=Juhn |first1=Mark S. |last2=Balisi |first2=Mairin A. |last3=Doughty |first3=Evan M. |last4=Friscia |first4=Anthony R. |last5=Howenstine |first5=Aidan O. |last6=Jacquemetton |first6=Christiane |last7=Marcot |first7=Jonathan |last8=Nugen |first8=Sarah |last9=Van Valkenburgh |first9=Blaire |date=30 September 2024 |title=Cenozoic climate change and the evolution of North American mammalian predator ecomorphology |journal=[[Paleobiology (journal)|Paleobiology]] |volume=50 |issue=3 |language=en |pages=452–461 |doi=10.1017/pab.2024.27 |bibcode=2024Pbio...50..452J |issn=0094-8373 |doi-access=free }}</ref>

Cenozoic [[Calcareous nannofossils|calcareous nannoplankton]] experienced rapid rates of speciation and reduced species longevity, while suffering prolonged declines in diversity during the Eocene and Neogene. [[Diatom|Diatoms]], in contrast, experienced major diversification over the Eocene, especially at high latitudes, as the world's oceans cooled.<ref>{{Cite journal |last=Bown |first=Paul R. |date=1 October 2005 |title=Calcareous nannoplankton evolution: a tale of two oceans |url=https://pubs.geoscienceworld.org/micropress/micropal/article-abstract/51/4/299/139808/Calcareous-nannoplankton-evolution-a-tale-of-two |journal=Micropaleontology |language=en |volume=51 |issue=4 |pages=299–308 |doi=10.2113/gsmicropal.51.4.299 |bibcode=2005MiPal..51..299B |issn=0026-2803 |access-date=8 January 2024 |via=GeoScienceWorld|url-access=subscription }}</ref> Diatom diversification was particularly concentrated at the Eocene-Oligocene boundary. A second major pulse of diatom diversification occurred over the course of the Middle and Late Miocene.<ref>{{Cite journal |last1=Falkowski |first1=Paul G. |last2=Katz |first2=Miriam E. |last3=Knoll |first3=Andrew H. |last4=Quigg |first4=Antonietta |last5=Raven |first5=John A. |last6=Schofield |first6=Oscar |last7=Taylor |first7=F. J. R. |date=16 July 2004 |title=The Evolution of Modern Eukaryotic Phytoplankton |url=https://www.science.org/doi/10.1126/science.1095964 |journal=[[Science (journal)|Science]] |language=en |volume=305 |issue=5682 |pages=354–360 |doi=10.1126/science.1095964 |pmid=15256663 |bibcode=2004Sci...305..354F |issn=0036-8075 |access-date=8 March 2024|url-access=subscription }}</ref>

==See also==
{{Portal|Earth sciences}}
* [[Cretaceous–Paleogene boundary]] (K–T boundary)
* [[Geologic time scale]]
* [[Late Cenozoic Ice Age]]

==References==
{{Reflist}}

==Further reading==
* {{cite book|title=After the Dinosaurs: The Age of Mammals|first= Donald R.|last= Prothero|location= Bloomington, Indiana|publisher= Indiana University Press|year= 2006 |isbn=978-0-253-34733-6}}

==External links==
{{Wikisource1911Enc|Cainozoic}}
{{Commons category|Cenozoic}}
* [http://museum.wa.gov.au/explore/dinosaur-discovery/age-mammals Western Australian Museum – The Age of the Mammals]
* [https://ghkclass.com/ghkC.html?cenozoic Cenozoic (chronostratigraphy scale)]

{{Geological history|p|c}}
{{Authority control}}

[[Category:Cenozoic| ]]
[[Category:Geological eras]]
[[Category:1840s neologisms]]