Editing Oligocene (section)

===Flora===
The Oi1 event of the Eocene-Oligocene transition covered the continent of Antarctica with ice sheets, leaving ''[[Nothofagus]]'' and mosses and ferns clinging to life around the periphery of Antarctica in tundra conditions.{{sfn|Francis|Marenssi|Levy|Hambrey|2008}}

[[Angiosperm]]s continued their expansion throughout the world as tropical and sub-[[tropical forest]]s were replaced by [[temperate deciduous forest]]s. Open [[plain]]s and [[desert]]s became more common and [[grass]]es expanded from their water-bank habitat in the Eocene moving out into open tracts.{{sfn|Torsvik|Cocks|2017|p=255}} The decline in pCO2 favored [[C4 photosynthesis]],<ref>{{cite journal |last1=Christin |first1=Pascal-Antoine |last2=Besnard |first2=Guillaume |last3=Samaritani |first3=Emanuela |last4=Duvall |first4=Melvin R. |last5=Hodkinson |first5=Trevor R. |last6=Savolainen |first6=Vincent |last7=Salamin |first7=Nicolas |title=Oligocene CO2 Decline Promoted C4 Photosynthesis in Grasses |journal=Current Biology |date=January 2008 |volume=18 |issue=1 |pages=37–43 |doi=10.1016/j.cub.2007.11.058|pmid=18160293 |hdl=2262/82791 |s2cid=16946058 |hdl-access=free }}</ref> which is found only in angiosperms and is particularly characteristic of grasses.<ref>{{cite journal | vauthors = Sage RF | title = A portrait of the C4 photosynthetic family on the 50th anniversary of its discovery: species number, evolutionary lineages, and Hall of Fame | journal = Journal of Experimental Botany | volume = 67 | issue = 14 | pages = 4039–56 | date = July 2016 | pmid = 27053721 | doi = 10.1093/jxb/erw156 | doi-access = free }}</ref> However, even at the end of the period, grass was not quite common enough for modern [[savanna]]s.{{sfn|Torsvik|Cocks|2017|p=255}}

In North America, much of the dense forest was replaced by patchy scrubland with riparian forests.{{sfn|Prothero|2005|p=475}}<ref name="Late Eocene and Oligocene paleosols"/> Subtropical species dominated with [[cashew]]s<ref>{{cite journal |last1=Méndez-Cárdenas |first1=Juliana P. |last2=Cevallos-Ferriz |first2=Sergio R.S. |last3=Calvillo-Canadell |first3=Laura |last4=Rodríguez-Yam |first4=Gabriel A. |last5=Borja |first5=Amparo M. |last6=Martínez-Cabrera |first6=Hugo I. |title=Loxopterygium wood in Coayuca de Andrade, Oligocene of Puebla, Mexico |journal=[[Review of Palaeobotany and Palynology]] |date=August 2014 |volume=207 |pages=38–43 |doi=10.1016/j.revpalbo.2014.04.004|bibcode=2014RPaPa.207...38M }}</ref> and [[lychee]] trees present,<ref>{{cite journal |last1=Buerki |first1=Sven |last2=Forest |first2=Félix |last3=Stadler |first3=Tanja |last4=Alvarez |first4=Nadir |date=July 2013 |title=The abrupt climate change at the Eocene–Oligocene boundary and the emergence of South-East Asia triggered the spread of sapindaceous lineages |journal=[[Annals of Botany]] |volume=112 |issue=1 |pages=151–160 |doi=10.1093/aob/mct106 |pmc=3690995 |pmid=23723259}}</ref> and temperate woody plants such as [[rose]]s, [[beech]]es,<ref>{{cite journal |last1=Denk |first1=Thomas |last2=Grimm |first2=Guido W. |date=December 2009 |title=The biogeographic history of beech trees |url=https://www.sciencedirect.com/science/article/abs/pii/S0034666709001353 |journal=[[Review of Palaeobotany and Palynology]] |volume=158 |issue=1–2 |pages=83–100 |bibcode=2009RPaPa.158...83D |doi=10.1016/j.revpalbo.2009.08.007 |access-date=15 December 2023 |via=Elsevier Science Direct}}</ref> and [[pine]]s{{sfn|Torsvik|Cocks|2017|p=254}} were common. The [[legume]]s spread,<ref>{{cite journal |last1=Herendeen |first1=Patrick S. |last2=Dilcher |first2=David L. |title=Fossil mimosoid legumes from the Eocene and Oligocene of southeastern North America |journal=[[Review of Palaeobotany and Palynology]] |date=March 1990 |volume=62 |issue=3–4 |pages=339–361 |doi=10.1016/0034-6667(90)90094-Y|bibcode=1990RPaPa..62..339H }}</ref> while [[Cyperaceae|sedge]]s<ref>{{cite journal |last1=Escudero |first1=Marcial |last2=Hipp |first2=Andrew L. |last3=Waterway |first3=Marcia J. |last4=Valente |first4=Luis M. |title=Diversification rates and chromosome evolution in the most diverse angiosperm genus of the temperate zone (Carex, Cyperaceae) |journal=Molecular Phylogenetics and Evolution |date=June 2012 |volume=63 |issue=3 |pages=650–655 |doi=10.1016/j.ympev.2012.02.005|pmid=22366369 }}</ref> and [[fern]]s continued their ascent.<ref>{{cite journal |last1=Devore |first1=M.L. |last2=Pigg |first2=K.B. |title=Floristic composition and comparison of middle Eocene to late Eocene and Oligocene floras in North America |journal=Bulletin of Geosciences |date=22 March 2010 |pages=111–134 |doi=10.3140/bull.geosci.1135|doi-access=free }}</ref>

In Europe, floral assemblages became increasingly affected by strengthening seasonality as it related to wildfire activity.<ref>{{Cite journal |last1=Uhl |first1=Dieter |last2=Spiekermann |first2=Rafael |last3=Wuttke |first3=Michael |last4=Poschmann |first4=Markus J. |last5=Jasper |first5=André |date=1 February 2022 |title=Wildfires during the Paleogene (late Eocene–late Oligocene) of the Neuwied Basin (W-Germany) |url=https://www.sciencedirect.com/science/article/pii/S0034666721001895 |journal=[[Review of Palaeobotany and Palynology]] |volume=297 |pages=104565 |doi=10.1016/j.revpalbo.2021.104565 |bibcode=2022RPaPa.29704565U |s2cid=244364779 |issn=0034-6667 |access-date=15 December 2023 |via=Elsevier Science Direct}}</ref>

In [[Pakistan]], the flora consisted mainly of dry but dense forests.<ref>{{Cite journal |last=Martin |first=C. |last2=Bentaleb |first2=I. |last3=Antoine |first3=P.-O. |date=15 October 2011 |title=Pakistan mammal tooth stable isotopes show paleoclimatic and paleoenvironmental changes since the early Oligocene |url=https://www.sciencedirect.com/science/article/abs/pii/S0031018211003932 |journal=[[Palaeogeography, Palaeoclimatology, Palaeoecology]] |language=en |volume=311 |issue=1-2 |pages=19–29 |doi=10.1016/j.palaeo.2011.07.010 |access-date=6 January 2025 |via=Elsevier Science Direct}}</ref> In northern China, there was a progressive ascendance of open, grassy environments.<ref>{{Cite journal |last=Gomes Rodrigues |first=Helder |last2=Marivaux |first2=Laurent |last3=Vianey-Liaud |first3=Monique |date=1 November 2012 |title=Expansion of open landscapes in Northern China during the Oligocene induced by dramatic climate changes: Paleoecological evidence |url=https://www.sciencedirect.com/science/article/abs/pii/S0031018212004269 |journal=[[Palaeogeography, Palaeoclimatology, Palaeoecology]] |language=en |volume=358-360 |pages=62–71 |doi=10.1016/j.palaeo.2012.07.025 |access-date=6 January 2025 |via=Elsevier Science Direct}}</ref> The Ha Long megafossil flora from the Dong Ho Formation of Oligocene age shows that the Oligocene flora of what is now [[Vietnam]] was very similar to its present flora.<ref>{{cite journal |last1=Huang |first1=Jian |last2=Spicer |first2=Robert A. |last3=Li |first3=Shu-Feng |last4=Liu |first4=Jia |last5=Do |first5=Truong Van |last6=Nguyen |first6=Hung Ba |last7=Zhou |first7=Zhe-Kun |last8=Su |first8=Tao |date=1 May 2022 |title=Long-term floristic and climatic stability of northern Indochina: Evidence from the Oligocene Ha Long flora, Vietnam |url=https://www.sciencedirect.com/science/article/abs/pii/S0031018222001006 |journal=[[Palaeogeography, Palaeoclimatology, Palaeoecology]] |volume=593 |page=110930 |doi=10.1016/j.palaeo.2022.110930 |bibcode=2022PPP...59310930H |s2cid=247368063 |access-date=13 February 2023}}</ref>

Kelps make their first appearance in the fossil record during the earliest Oligocene.<ref>{{Cite journal |last1=Kiel |first1=Steffen |last2=Goedert |first2=James L. |last3=Huynh |first3=Tony L. |last4=Krings |first4=Michael |last5=Parkinson |first5=Dula |last6=Romero |first6=Rosemary |last7=Looy |first7=Cindy V. |date=16 January 2024 |title=Early Oligocene kelp holdfasts and stepwise evolution of the kelp ecosystem in the North Pacific |journal=[[Proceedings of the National Academy of Sciences of the United States of America]] |language=en |volume=121 |issue=4 |pages=e2317054121 |doi=10.1073/pnas.2317054121 |issn=0027-8424 |pmc=10823212 |pmid=38227671 }}</ref>