neogene

In ICS terminology, from upper (later, more recent) to lower (earlier):

The Pliocene Epoch is subdivided into two ages:

• Piacenzian Age, preceded by
• Zanclean Age

The Miocene Epoch is subdivided into six ages:

• Messinian Age, preceded by
• Tortonian Age
• Serravallian Age
• Langhian Age
• Burdigalian Age
• Aquitanian Age

In different geophysical regions of the world, other regional names are also used for the same or overlapping ages and other timeline subdivisions.

The terms Neogene System (formal) and Upper Tertiary System (informal) describe the rocks deposited during the Neogene Period.

The continents in the Neogene were very close to their current positions. The Isthmus of Panama formed, connecting North and South America. The Indian subcontinent continued to collide with Asia, forming the Himalayas. Sea levels fell, creating land bridges between Africa and Eurasia and between Eurasia and North America.

The global climate became more seasonal and continued an overall drying and cooling trend which began during the Paleogene. The Early Miocene was relatively cool;{{Cite journal |last1=Scotese |first1=Christopher R. |last2=Song |first2=Haijun |last3=Mills |first3=Benjamin J.W. |last4=van der Meer |first4=Douwe G. |date=April 2021 |title=Phanerozoic paleotemperatures: The earth's changing climate during the last 540 million years |url=https://www.researchgate.net/publication/348351275 |journal=Earth-Science Reviews |volume=215 |pages=103503 |bibcode=2021ESRv..21503503S |doi=10.1016/j.earscirev.2021.103503 |issn=0012-8252 |archive-url=https://web.archive.org/web/20210108000000/http://dx.doi.org/10.1016/j.earscirev.2021.103503 |archive-date=8 January 2021 |s2cid=233579194 |access-date=17 July 2023}} [https://eprints.whiterose.ac.uk/169823/ Alt URL] Early Miocene mid-latitude seawater and continental thermal gradients were already very similar to those of the present.{{cite journal |last1=Goedert |first1=Jean |last2=Amiot |first2=Romain |last3=Arnaut-Godet |first3=Florent |last4=Cuny |first4=Gilles |last5=Fourel |first5=François |last6=Hernandez |first6=Jean-Alexis |last7=Pedreira-Segade |first7=Ulysse |last8=Lécuyer |first8=Christophe |date=1 September 2017 |title=Miocene (Burdigalian) seawater and air temperatures estimated from the geochemistry of fossil remains from the Aquitaine Basin, France |url=https://www.sciencedirect.com/science/article/abs/pii/S0031018216307568 |journal=Palaeogeography, Palaeoclimatology, Palaeoecology |volume=481 |pages=14–28 |doi=10.1016/j.palaeo.2017.04.024 |bibcode=2017PPP...481...14G |access-date=30 November 2022|url-access=subscription }} During the Middle Miocene, Earth entered a warm phase known as the Middle Miocene Climatic Optimum (MMCO), which was driven by the emplacement of the Columbia River Basalt Group.{{cite journal |last1=Kasbohm |first1=Jennifer |last2=Schoene |first2=Blair |date=19 September 2018 |title=Rapid eruption of the Columbia River flood basalt and correlation with the mid-Miocene climate optimum |journal=Science Advances |volume=4 |issue=9 |pages=eaat8223 |doi=10.1126/sciadv.aat8223 |pmid=30255148 |pmc=6154988 |bibcode=2018SciA....4.8223K }} Around 11 Ma, the Middle Miocene Warm Interval gave way to the much cooler Late Miocene. The ice caps on both poles began to grow and thicken, a process enhanced by positive feedbacks from increased formation of sea ice.{{cite journal |last1=DeConto |first1=Robert |last2=Pollard |first2=David |last3=Harwood |first3=David |date=24 August 2007 |title=Sea ice feedback and Cenozoic evolution of Antarctic climate and ice sheets |journal=Paleoceanography and Paleoclimatology |volume=22 |issue=3 |pages=1–18 |doi=10.1029/2006PA001350 |doi-access=free |bibcode=2007PalOc..22.3214D }} Between 7 and 5.3 Ma, a decrease in global temperatures termed the Late Miocene Cooling (LMC) ensued, driven by decreases in carbon dioxide concentrations.{{cite journal |last1=Tanner |first1=Thomas |last2=Hernández-Almeida |first2=Iván |last3=Drury |first3=Anna Joy |last4=Guitián |first4=José |last5=Stoll |first5=Heather |date=10 December 2020 |title=Decreasing Atmospheric CO2 During the Late Miocene Cooling |url=https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2020PA003925 |journal=Paleoceanography and Paleoclimatology |volume=35 |issue=12 |doi=10.1029/2020PA003925 |bibcode=2020PaPa...35.3925T |s2cid=230534117 |access-date=17 March 2023|url-access=subscription }} During the Pliocene, from about 5.3 to 2.7 Ma, another warm interval occurred, being known as the Pliocene Warm Interval (PWI), interrupting the longer-term cooling trend. The Pliocene Thermal Maximum (PTM) occurred between 3.3 and 3.0 Ma. During the Pliocene, Green Sahara phases of wet conditions in North Africa were frequent and occurred about every 21 kyr, being especially intense when Earth's orbit's eccentricity was high.{{Cite journal |last1=Lupien |first1=Rachel |last2=Uno |first2=Kevin |last3=Rose |first3=Cassaundra |last4=deRoberts |first4=Nicole |last5=Hazan |first5=Cole |last6=de Menocal |first6=Peter |last7=Polissar |first7=Pratigya |date=9 October 2023 |title=Low-frequency orbital variations controlled climatic and environmental cycles, amplitudes, and trends in northeast Africa during the Plio-Pleistocene |journal=Communications Earth & Environment |language=en |volume=4 |issue=1 |page=360 |doi=10.1038/s43247-023-01034-7 |issn=2662-4435 |doi-access=free |bibcode=2023ComEE...4..360L }} The PWI had similar levels of atmospheric carbon dioxide to contemporary times and is often seen as an analogous climate to the projected climate of the near future as a result of anthropogenic global warming.{{Cite journal |last1=Burke |first1=K. D. |last2=Williams |first2=J. W. |last3=Chandler |first3=M. A. |last4=Haywood |first4=A. M. |last5=Lunt |first5=D. J. |last6=Otto-Bliesner |first6=B. L. |date=26 December 2018 |title=Pliocene and Eocene provide best analogs for near-future climates |journal=Proceedings of the National Academy of Sciences of the United States of America |language=en |volume=115 |issue=52 |pages=13288–13293 |doi=10.1073/pnas.1809600115 |doi-access=free |issn=0027-8424 |pmc=6310841 |pmid=30530685 |bibcode=2018PNAS..11513288B }} Towards the end of the Pliocene, decreased heat transport towards the Antarctic resulting from a weakening of the Indonesian Throughflow (ITF) cooled the Earth, a process that exacerbated itself in a positive feedback as sea levels dropped and the ITF diminished and further limited the heat transported southward by the Leeuwin Current.{{Cite journal |last1=De Vleeschouwer |first1=David |last2=Auer |first2=Gerald |last3=Smith |first3=Rebecca |last4=Bogus |first4=Kara |last5=Christensen |first5=Beth |last6=Groeneveld |first6=Jeroen |last7=Petrick |first7=Benjamin |last8=Henderiks |first8=Jorijntje |last9=Castañeda |first9=Isla S. |last10=O'Brien |first10=Evan |last11=Ellinghausen |first11=Maret |last12=Gallagher |first12=Stephen J. |last13=Fulthorpe |first13=Craig S. |last14=Pälike |first14=Heiko |date=October 2018 |title=The amplifying effect of Indonesian Throughflow heat transport on Late Pliocene Southern Hemisphere climate cooling |url=https://linkinghub.elsevier.com/retrieve/pii/S0012821X18304412 |journal=Earth and Planetary Science Letters |language=en |volume=500 |pages=15–27 |doi=10.1016/j.epsl.2018.07.035 |bibcode=2018E&PSL.500...15D |access-date=13 April 2024 |via=Elsevier Science Direct|url-access=subscription }} By the end of the period the first of a series of glaciations of the current Ice Age began.{{cite book |last1=Benn |first1=Douglas I. |title=Glaciers & glaciation |date=2010 |publisher=Hodder Education |location=London |isbn=9780340905791 |pages=15–21 |edition=2nd}}

Marine and continental flora and fauna have a modern appearance. The reptile group Choristodera went extinct in the early part of the period, while the amphibians known as Allocaudata disappeared at the end of it. Neogene also marked the end of the reptilian genera Langstonia and Barinasuchus, terrestrial predators that were the last surviving members of Sebecosuchia, a group related to crocodiles. The oceans were dominated by large carnivores like megalodons and livyatans, and 19 million years ago about 70% of all pelagic shark species disappeared.[https://www.discovermagazine.com/environment/almost-20-million-years-ago-sharks-nearly-went-extinct-nobody-knows-why Almost 20 Million Years Ago, Sharks Nearly Went Extinct] Mammals and birds continued to be the dominant terrestrial vertebrates, and took many forms as they adapted to various habitats. Ungulates in North America became noticeably more cursorial and increased their stride lengths across the Oligocene-Miocene boundary, likely in response to the increased habitat openness during the Miocene.{{Cite journal |last1=Levering |first1=David |last2=Hopkins |first2=Samantha |last3=Davis |first3=Edward |date=15 January 2017 |title=Increasing locomotor efficiency among North American ungulates across the Oligocene-Miocene boundary |url=https://www.sciencedirect.com/science/article/pii/S0031018216307738 |journal=Palaeogeography, Palaeoclimatology, Palaeoecology |language=en |volume=466 |pages=279–286 |doi=10.1016/j.palaeo.2016.11.036 |bibcode=2017PPP...466..279L |access-date=13 February 2022 |via=Elsevier Science Direct|url-access=subscription }} An explosive radiation of ursids took place at the Miocene-Pliocene boundary.{{Cite journal |last1=Krause |first1=Johannes |last2=Unger |first2=Tina |last3=Noçon |first3=Aline |last4=Malaspinas |first4=Anna-Sapfo |last5=Kolokotronis |first5=Sergios-Orestis |last6=Stiller |first6=Mathias |last7=Soibelzon |first7=Leopoldo |last8=Spriggs |first8=Helen |last9=Dear |first9=Paul H |last10=Briggs |first10=Adrian W |last11=Bray |first11=Sarah CE |last12=O'Brien |first12=Stephen J |last13=Rabeder |first13=Gernot |last14=Matheus |first14=Paul |last15=Cooper |first15=Alan |last16=Slatkin |first16=Montgomery |last17=Pääbo |first17=Svante |last18=Hofreiter |first18=Martin |date=28 July 2008 |title=Mitochondrial genomes reveal an explosive radiation of extinct and extant bears near the Miocene-Pliocene boundary |journal=BMC Evolutionary Biology |language=en |volume=8 |issue=1 |page=220 |doi=10.1186/1471-2148-8-220 |doi-access=free |issn=1471-2148 |pmc=2518930 |pmid=18662376 |bibcode=2008BMCEE...8..220K }} The first hominins, the ancestors of humans, may have appeared in southern Europe and migrated into Africa.{{cite web|url=https://phys.org/news/2017-05-scientists-million-year-old-pre-human-balkans.html|title=Scientists find 7.2-million-year-old pre-human remains in the Balkans|website=Phys.org|access-date=17 December 2017}}{{cite web|url=https://www.researchgate.net/blog/post/9-7-million-year-old-teeth-fossils-raise-questions-about-human-origin|title=9.7 million-year-old teeth found in Germany resemble those of human ancestors in Africa|website=ResearchGate|access-date=17 December 2017}} The first humans (belonging to the species Homo habilis) appeared in Africa near the end of the period.

About 20 million years ago gymnosperms in the form of some conifer and cycad groups started to diversify and produce more species due to the changing conditions.[https://www.floridamuseum.ufl.edu/science/gymnosperm-origin-evolution/ DNA duplication linked to the origin and evolution of pine trees and their relatives] In response to the cooler, seasonal climate, tropical plant species gave way to deciduous ones and grasslands replaced many forests. Grasses therefore greatly diversified, and herbivorous mammals evolved alongside it, creating the many grazing animals of today such as horses, antelope, and bison. Ice age mammals like the mammoths and woolly rhinoceros were common in Pliocene. With lower levels of {{CO2}} in the atmosphere, {{C4}} plants expanded and reached ecological dominance in grasslands during the last 10 million years. Also Asteraceae (daisies) went through a significant adaptive radiation.{{cite journal | doi=10.1038/s41467-021-27897-y | title=The rise of grasslands is linked to atmospheric CO2 decline in the late Palaeogene | year=2022 | last1=Palazzesi | first1=Luis | last2=Hidalgo | first2=Oriane | last3=Barreda | first3=Viviana D. | last4=Forest | first4=Félix | last5=Höhna | first5=Sebastian | journal=Nature Communications | volume=13 | issue=1 | page=293 | pmid=35022396 | pmc=8755714 | bibcode=2022NatCo..13..293P }} Eucalyptus fossil leaves occur in the Miocene of New Zealand, where the genus is not native today, but have been introduced from Australia.{{cite web|url=https://mikepole.wordpress.com/2014/09/22/eucalyptus-fossils-in-new-zealand-the-thin-end-of-the-wedge/|title=Eucalyptus fossils in New Zealand – the thin end of the wedge – Mike Pole|date=22 September 2014}}

The Neogene traditionally ended at the end of the Pliocene Epoch, just before the older definition of the beginning of the Quaternary Period; many time scales show this division.

However, there was a movement amongst geologists (particularly marine geologists) to also include ongoing geological time (Quaternary) in the Neogene, while others (particularly terrestrial geologists) insist the Quaternary to be a separate period of distinctly different record. The somewhat confusing terminology and disagreement amongst geologists on where to draw what hierarchical boundaries is due to the comparatively fine divisibility of time units as time approaches the present, and due to geological preservation that causes the youngest sedimentary geological record to be preserved over a much larger area and to reflect many more environments than the older geological record.{{cite book |last1=Tucker |first1=M.E. |author-link1=Tucker, M. E. |title=Sedimentary petrology : an introduction to the origin of sedimentary rocks |date=2001 |publisher=Blackwell Science |location=Osney Nead, Oxford, UK |isbn=978-0-632-05735-1 |edition=3rd |language=en}} By dividing the Cenozoic Era into three (arguably two) periods (Paleogene, Neogene, Quaternary) instead of seven epochs, the periods are more closely comparable to the duration of periods in the Mesozoic and Paleozoic Eras.

The International Commission on Stratigraphy (ICS) once proposed that the Quaternary be considered a sub-era (sub-erathem) of the Neogene, with a beginning date of 2.58 Ma, namely the start of the Gelasian Stage. In the 2004 proposal of the ICS, the Neogene would have consisted of the Miocene and Pliocene Epochs.Lourens, L., Hilgen, F., Shackleton, N.J., Laskar, J., Wilson, D., (2004) "The Neogene Period". In: Gradstein, F., Ogg, J., Smith, A.G. (Eds.), Geologic Time Scale, Cambridge University Press, Cambridge. The International Union for Quaternary Research (INQUA) counterproposed that the Neogene and the Pliocene end at 2.58 Ma, that the Gelasian be transferred to the Pleistocene, and the Quaternary be recognized as the third period in the Cenozoic, citing key changes in Earth's climate, oceans, and biota that occurred 2.58 Ma and its correspondence to the Gauss-Matuyama magnetostratigraphic boundary.[http://www.inqua.tcd.ie/documents/QP%2016-1.pdf Clague, John et al. (2006) "Open Letter by INQUA Executive Committee"] {{webarchive|url=https://web.archive.org/web/20060923053134/http://www.inqua.tcd.ie/documents/QP%2016-1.pdf |date=2006-09-23 }} Quaternary Perspective, the INQUA Newsletter International Union for Quaternary Research 16(1){{cite journal |last1=Clague |first1=John |display-authors=etal|title=Open Letter by INQUA Executive Committee |journal=Quaternary Perspective, the INQUA Newsletter |date=2006 |volume=16 |issue=1 |url=http://www.inqua.tcd.ie/documents/QP%2016-1.pdf |access-date=2006-09-23 |doi=10.1016/j.quaint.2006.06.001|archive-url=https://web.archive.org/web/20060923053134/http://www.inqua.tcd.ie/documents/QP%2016-1.pdf |archive-date=2006-09-23|publisher=International Union for Quaternary Research|issn=1040-6182|pages=158–159}} In 2006 ICS and INQUA reached a compromise that made Quaternary a sub-era, subdividing Cenozoic into the old classical Tertiary and Quaternary, a compromise that was rejected by International Union of Geological Sciences because it split both Neogene and Pliocene in two.{{cite web|url=http://www.stratigraphy.org/report06.pdf|title=ICS: Consolidated Annual Report for 2006|website=Stratigraphy.org|access-date=15 June 2007}}

Following formal discussions at the 2008 International Geological Congress in Oslo, Norway,{{cite web|url=http://www.33igc.org/coco/LayoutPage.aspx|title=Geoparks and Geotourism – Field Excursion of South America|website=33igc.org|access-date=17 December 2017}} the ICS decided in May 2009 to make the Quaternary the youngest period of the Cenozoic Era with its base at 2.58 Mya and including the Gelasian Age, which was formerly considered part of the Neogene Period and Pliocene Epoch.{{cite web|url=http://www.quaternary.stratigraphy.org.uk/correlation/GSAchron09.jpg|title=See the 2009 version of the ICS geologic time scale|website=Quaternary.stratigraphy.org.uk|access-date=17 December 2017}} Thus the Neogene Period ends bounding the succeeding Quaternary Period at 2.58 Mya.

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{{Wikisource portal|Cenozoic#Neogene}}

• {{cite web |title=Digital Atlas of Neogene Life for the Southeastern United States |url=http://geosun.sjsu.edu/~jhendricks/AtlasTemp/neogene.html |publisher=San Jose State University |access-date=21 September 2018 |archive-url=https://web.archive.org/web/20130423191403/http://geosun.sjsu.edu/~jhendricks/AtlasTemp/neogene.html |archive-date=2013-04-23}}

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