Editing Oligocene (section)

==Biosphere==
[[File:Turtle Cove mural - Roger Witter.jpg|thumb|300px|Restoration of ''[[Nimravus]]'' (far left) and other animals from the [[Turtle Cove Formation]]]]
The early Eocene climate was very warm, with [[crocodilians]] and temperate plants thriving north of the [[Arctic Circle]]. The cooling trend that began in the middle Eocene continued into the Oligocene, bringing both poles well below freezing for the first time in the [[Phanerozoic]]. The cooling climate, together with the opening of some land bridges and the closing of others, led to a profound reorganization of the biosphere and loss of taxonomic diversity. Land animals and marine organisms reached a Phanerozoic low in diversity by the late Oligocene, and the temperate forests and jungles of the Eocene were replaced by forest and scrubland. The closing of the Tethys Seaway destroyed its tropical biota.{{sfn|Prothero|2005|pp=473–477}}

===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>

===Fauna===
[[File:Ancient Mammal at Denver Museum of Nature and Science.jpg|thumb|Life restoration of ''[[Daeodon]]'']]
[[File:Paraceratherium_transouralicum.jpg|thumb|''[[Paraceratherium]]'' restored next to ''[[Hyaenodon]]'']]

Most extant mammal families had appeared by the end of the Oligocene. These included primitive three-toed horses, rhinoceroses, camels, deer, and peccaries. Carnivores such as [[canidae|dogs]], [[nimravids]], bears, weasels, and raccoons began to replace the [[creodonts]] that had dominated the Paleocene in the Old World. Rodents and rabbits underwent tremendous diversification due to the increase in suitable habitats for ground-dwelling seed eaters, as habitats for squirrel-like nut- and fruit-eaters diminished. The primates, once present in Eurasia, were reduced in range to Africa and South America.{{sfn|Prothero|2005|p=476}} Many groups, such as [[equid]]s,<ref>{{cite book |last1=Floyd |first1=Andrea E. |title=Equine podiatry |date=2007 |publisher=Elsevier Saunders |location=Philadelphia, Pa. |isbn=9781416064596 |chapter=Evolution of the equine digit and its relevance to the modern horse}}</ref> [[entelodont]]s, [[rhino]]s, [[merycoidodont]]s, and [[camelid]]s, became more able to run during this time, adapting to the plains that were spreading as the Eocene rainforests receded.<ref>{{cite book |last1=Prothero |first1=Donald R. |title=Horns, tusks, and flippers : the evolution of hoofed mammals |date=2002 |publisher=Johns Hopkins University Press |location=Baltimore |isbn=9780801871351 |page=19 |url=https://books.google.com/books?id=kWpQX-sfsLgC&q=running |access-date=10 August 2021 |chapter=Cloven hooves}}</ref> [[Brontotheriidae|Brontotheres]] died out in the Earliest Oligocene, and [[creodonts]] died out outside [[Africa]] and the [[Middle East]] at the end of the period. [[Multituberculates]], an ancient lineage of primitive mammals that originated back in the [[Jurassic]], also became extinct in the Oligocene, aside from the [[gondwanathere]]s.<ref>{{cite journal |last1=Prothero |first1=Donald R. |title=North American mammalian diversity and Eocene–Oligocene extinctions |journal=[[Paleobiology (journal)|Paleobiology]] |date=1985 |volume=11 |issue=4 |pages=389–405 |doi=10.1017/S0094837300011696|bibcode=1985Pbio...11..389P |s2cid=87346202 }}</ref>

The Eocene-Oligocene transition in Europe and Asia has been characterized as the Grande Coupure.<ref>{{Cite journal |last1=Mennecart |first1=Bastien |last2=Aiglstorfer |first2=Manuela |last3=Li |first3=Yikun |last4=Li |first4=Chunxiao |last5=Wang |first5=ShiQi |date=6 September 2021 |title=Ruminants reveal Eocene Asiatic palaeobiogeographical provinces as the origin of diachronous mammalian Oligocene dispersals into Europe |journal=[[Scientific Reports]] |language=en |volume=11 |issue=1 |pages=17710 |doi=10.1038/s41598-021-96221-x |issn=2045-2322 |doi-access=free |pmid=34489502 |pmc=8421421 |bibcode=2021NatSR..1117710M }}</ref> The lowering of sea levels closed the Turgai Strait across the Obik Sea, which had previously separated Asia from Europe. This allowed Asian mammals, such as [[rhinoceroses]] and [[ruminants]], to enter Europe and drive endemic species to extinction.{{sfn|Prothero|2005|p=476}} Lesser faunal turnovers occurred simultaneously with the Oi2 event and towards the end of the Oligocene.<ref>{{cite journal |last1=Barberà |first1=X. |last2=Cabrera |first2=L. |last3=Marzo |first3=M. |last4=Parés |first4=J.M. |last5=Agustı́ |first5=J. |title=A complete terrestrial Oligocene magnetobiostratigraphy from the Ebro Basin, Spain |journal=Earth and Planetary Science Letters |date=April 2001 |volume=187 |issue=1–2 |pages=1–16 |doi=10.1016/S0012-821X(01)00270-9|bibcode=2001E&PSL.187....1B |url=http://doc.rero.ch/record/16006/files/PAL_E3760.pdf }}</ref> There was significant diversification of mammals in Eurasia, including the giant [[indricotheres]], that grew up to {{convert|6|m|sigfig=1|sp=us}} at the shoulder and weighed up to 20 tons. ''[[Paraceratherium]]'' was one of the largest land mammals ever to walk the Earth.<ref>{{cite book | last = Prothero | first = D. | title = Rhinoceros Giants: The Palaeobiology of Indricotheres| publisher = Indiana University Press | year = 2013 | location = Indiana | isbn = 978-0-253-00819-0 |url=https://books.google.com/books?id=fbyn88ExO9IC&pg=PA87 |pages=87–106}}</ref> However, the indricotheres were an exception to a general tendency for Oligocene mammals to be much smaller than their Eocene counterparts.{{sfn|Torsvik|Cocks|2017|p=255}} The earliest deer, giraffes, pigs, and cattle appeared in the mid-Oligocene in Eurasia.{{sfn|Prothero|2005|p=476}} The first [[felid]], ''[[Proailurus]]'', originated in Asia during the late Oligocene and spread to Europe.<ref name =Mott>{{cite web| last = Mott| first = Maryann| title = Cats Climb New Family Tree| publisher = National Geographic News| date = January 11, 2006 | url = http://news.nationalgeographic.com/news/2006/01/0111_060111_cat_evolution.html| access-date = 2006-07-15 |url-status=dead |archive-url=https://web.archive.org/web/20071012220411/http://news.nationalgeographic.com/news/2006/01/0111_060111_cat_evolution.html |archive-date=Oct 12, 2007 }}</ref>
[[File:Paraphysornis BW-2r.jpg|thumb|Life restoration of ''[[Paraphysornis]]'']]
There was only limited migration between Asia and North America.{{sfn|Prothero|2005|p=476}} The cooling of central North America at the Eocene-Oligocene transition resulted in a large turnover of [[gastropod]]s, [[amphibian]]s, and [[reptile]]s. Mammals were much less affected.<ref name="Large temperature drop across the E"/> Crocodilians and pond turtles replaced by dry land tortoises. Molluscs shifted to more drought-tolerant forms.{{sfn|Prothero|2005|p=475}} The [[White River Fauna]] of central North America inhabited a semiarid prairie home and included entelodonts like ''[[Archaeotherium]]'', camelids (such as ''[[Poebrotherium]]''), running [[rhino]]ceratoids, three-toed equids (such as ''[[Mesohippus]]''), [[nimravids]], [[protoceratidae|protoceratid]]s, and early [[canid]]s like ''[[Hesperocyon]]''.<ref>{{cite book |last1=Benton |first1=Rachel C. |last2=Terry | first2=Dennis O. Jr. |last3=Evanoff |first3=Emmett |last4=McDonald |first4=Hugh Gregory |title=The White River Badlands: Geology and Paleontology |publisher=Indiana University Press |date=2015 |location=Bloomington |isbn=9780253016089 |url=https://books.google.com/books?id=ZcFtCQAAQBAJ |access-date=10 August 2021}}</ref> Merycoidodonts, an endemic American group, were very diverse during this time.<ref>{{cite book |last1=Saarinen |first1=Juha |last2=Mantzouka |first2=Dimitra |last3=Sakala |first3=Jakub |title=Nature through Time |chapter=Aridity, Cooling, Open Vegetation, and the Evolution of Plants and Animals During the Cenozoic |series=Springer Textbooks in Earth Sciences, Geography and Environment |date=2020 |pages=83–107 |doi=10.1007/978-3-030-35058-1_3|isbn=978-3-030-35057-4 |s2cid=226435040 }}</ref>

[[File:Aegyptopithecus NT.jpg|thumb|''[[Aegyptopithecus]]'' is an early fossil [[Catarrhini|catarrhine]] that predates the divergence between [[hominoids]] ([[ape]]s) and [[Old World monkey]]s]]
Australia and South America became geographically isolated and developed their own distinctive endemic fauna. These included the New World and Old World monkeys. The South American continent was home to animals such as [[Pyrotheria|pyrothere]]s and [[Astrapotheria|astrapothere]]s, as well as [[litoptern]]s and [[notoungulate]]s. [[Sebecosuchian]]s, [[Phorusrhacidae|terror birds]], and carnivorous [[metathere]]s, like the [[Borhyaenidae|borhyaenids]] remained the dominant predators.<ref>{{cite journal |last1=Flynn |first1=John J |last2=Wyss |first2=André R |last3=Croft |first3=Darin A |last4=Charrier |first4=Reynaldo |title=The Tinguiririca Fauna, Chile: biochronology, paleoecology, biogeography, and a new earliest Oligocene South American Land Mammal 'Age' |journal=Palaeogeography, Palaeoclimatology, Palaeoecology |date=June 2003 |volume=195 |issue=3–4 |pages=229–259 |doi=10.1016/S0031-0182(03)00360-2|bibcode=2003PPP...195..229F |doi-access=free }}</ref>

Africa was also relatively isolated and retained its endemic fauna. These included [[mastodont]]s, hyraxes, arsinoitheres, and other archaic forms.{{sfn|Prothero|2005|p=476}} [[Egypt]] in the Oligocene was an environment of lush forested deltas.<ref>{{cite book |last1=Benton |first1=M. J. |title=Cowen's history of life |date=2019 |publisher=John Wiley & Sons Ltd |location=Hoboken, NJ |isbn=9781119482215 |edition=Sixth |page=306}}</ref> Nevertheless, the Early Oligocene saw a major reduction in the diversity of many Afro-Arabian mammal clades, including hyaenodonts, primates, and hystricognath and anomaluroid rodents.<ref>{{Cite journal |last1=de Vries |first1=Dorien |last2=Heritage |first2=Steven |last3=Borths |first3=Matthew R. |last4=Sallam |first4=Hesham M. |last5=Seiffert |first5=Erik R. |date=7 October 2021 |title=Widespread loss of mammalian lineage and dietary diversity in the early Oligocene of Afro-Arabia |journal=[[Communications Biology]] |language=en |volume=4 |issue=1 |page=1172 |doi=10.1038/s42003-021-02707-9 |issn=2399-3642 |doi-access=free |pmid=34621013 |pmc=8497553 }}</ref>

During the Oligocene, the Tethyan marine biodiversity hotspot collapsed as the Tethys Ocean contracted. The seas around Southeast Asia and Australia became the new dominant hotspot of marine biodiversity.<ref>{{cite journal |last1=Cowman |first1=P. F. |last2=Bellwood |first2=D. R. |date=10 October 2011 |title=Coral reefs as drivers of cladogenesis: expanding coral reefs, cryptic extinction events, and the development of biodiversity hotspots |journal=[[Journal of Evolutionary Biology]] |volume=24 |issue=12 |pages=2543–2562 |doi=10.1111/j.1420-9101.2011.02391.x |pmid=21985176 |doi-access=free }}</ref> At sea, 97% of marine snail species, 89% of clams, and 50% of echinoderms of the Gulf Coast did not survive past the earliest Oligocene. New species evolved, but the overall diversity diminished. Cold-water mollusks migrated around the Pacific Rim from Alaska and Siberia.{{sfn|Prothero|2005|p=476}} The marine animals of Oligocene oceans resembled today's fauna, such as the [[bivalves]]. Calcareous [[Cirratulidae|cirratulids]] appeared in the Oligocene.<ref name=Vinn2009>{{cite journal | author = Vinn, O. | year = 2009 | title = The ultrastructure of calcareous cirratulid (Polychaeta, Annelida) tubes | journal = Estonian Journal of Earth Sciences | volume = 58 | issue = 2 | pages = 153–156 | url = http://www.kirj.ee/public/Estonian_Journal_of_Earth_Sciences/2009/issue_2/earth-2009-2-153-156.pdf | access-date = 2012-09-16 | doi = 10.3176/earth.2009.2.06 | doi-access = free }}</ref>

The Oligocene saw the emergence of parrotfishes, as the centre of marine biodiversity shifted from the Central Tethys eastward into the [[Indo-Pacific]].<ref>{{cite journal |last1=Siqueira |first1=Alexandre C. |last2=Bellwood |first2=David R. |last3=Cowman |first3=Peter F. |date=4 June 2019 |title=Historical biogeography of herbivorous coral reef fishes: The formation of an Atlantic fauna |url=https://onlinelibrary.wiley.com/doi/abs/10.1111/jbi.13631 |journal=[[Journal of Biogeography]] |volume=46 |issue=7 |pages=1611–1624 |doi=10.1111/jbi.13631 |bibcode=2019JBiog..46.1611S |s2cid=195431434 |access-date=9 May 2023}}</ref> The fossil record of marine mammals is a little spotty during this time, and not as well known as the Eocene or Miocene, but some fossils have been found. The [[baleen whale]]s and [[toothed whales]] had just appeared, and their ancestors, the [[Archaeoceti|archaeocete]] [[cetacean]]s began to decrease in diversity due to their lack of echolocation, which was very useful as the water became colder and cloudier. Other factors to their decline could include climate changes and competition with today's modern cetaceans and the [[requiem shark]]s, which also appeared in this epoch. Early [[desmostylia]]ns, like ''[[Behemotops]]'', are known from the Oligocene. [[Pinnipeds]] appeared near the end of the epoch from an [[otter]]-like ancestor.<ref>{{cite web| last = Handwerk| first = Brian| title = Seal with "Arms" Discovered| publisher = National Geographic News| date = 2009-03-22| url = http://news.nationalgeographic.com/news/2009/04/090422-seal-evolution-missing-link.html| archive-url = https://web.archive.org/web/20090425125042/http://news.nationalgeographic.com/news/2009/04/090422-seal-evolution-missing-link.html| url-status = dead| archive-date = April 25, 2009| access-date = 2014-12-31}}</ref>

<gallery>
File:NMNH-USNMV15917Poebrotherium.jpg|''[[Poebrotherium]]''
File:Merycoidodon Skull Oligocene Left Side.jpg|''[[Merycoidodon]]''
File:Hoplophoneus primaevus (fossil false sabertooth cat) (Middle Oligocene; Nebraska, USA) 3 (32791323412).jpg|''[[Hoplophoneus]]''
File:Mesohippus barbouri Harvard.jpg|''[[Mesohippus]]''
File:Paraceratherium transouralicum skull.jpg|''[[Paraceratherium]]''
File:Paleoparadoxia Natural History Museum of Los Angeles County 20110330.jpg|''[[Paleoparadoxia]]''
File:Protoceras skeleton.jpg|''[[Protoceras]]''
File:Archaeotherium mortoni.JPG|''[[Archaeotherium]]''
File:Janjucetus hunderi skull.jpg|''[[Janjucetus]]''
</gallery>