Editing Bear (section)

===Evolution===
[[File:Plithocyon armagnacensis.JPG|thumb|left|''[[Plithocyon|Plithocyon armagnacensis]]'' skull, a member of the extinct subfamily Hemicyoninae from the [[Miocene]]]]

The earliest members of Ursidae belong to the extinct subfamily Amphicynodontinae, including ''[[Parictis]]'' (late [[Eocene]] to early middle [[Miocene]], 38–18&nbsp;[[Mya (unit)|Mya]]) and the slightly younger ''Allocyon'' (early [[Oligocene]], 34–30&nbsp;Mya), both from North America. These animals looked very different from today's bears, being small and [[raccoon]]-like in overall appearance, with diets perhaps more similar to that of a [[badger]]. ''Parictis'' does not appear in Eurasia and Africa until the Miocene.<ref name=Kemp>{{cite book |last=Kemp |first=T.S. |year=2005 |title=The Origin and Evolution of Mammals |url=https://archive.org/details/originevolutionm00kemp |url-access=limited |publisher=Oxford University Press |isbn=978-0-19-850760-4 |page=[https://archive.org/details/originevolutionm00kemp/page/n270 260]}}</ref> It is unclear whether late-Eocene ursids were also present in Eurasia, although faunal exchange across the [[Bering land bridge]] may have been possible during a major sea level low stand as early as the late Eocene (about 37&nbsp;Mya) and continuing into the early Oligocene.<ref name=Wang2>{{cite journal |author1=Banyue, Wang |author2=Zhanxiang, Qiu |year=2005 |title=Notes on Early Oligocene Ursids (Carnivora, Mammalia) from Saint Jacques, Nei Mongol, China |journal=Bulletin of the American Museum of Natural History |issue=279 |pages=116–124 |url=http://digitallibrary.amnh.org/dspace/bitstream/2246/447/22/B279a05.pdf |doi=10.1206/0003-0090(2003)279<0116:C>2.0.CO;2 |volume=279 |s2cid=26636569 |archive-url=https://web.archive.org/web/20090326201348/http://digitallibrary.amnh.org/dspace/bitstream/2246/447/22/B279a05.pdf |archive-date=2009-03-26 |url-status=live }}</ref> European genera morphologically very similar to ''Allocyon'', and to the much younger American ''[[Kolponomos]]'' (about 18 Mya),<ref>{{Cite journal |last1=Tedford |first1=R.H. |author-link=Richard H. Tedford |last2=Barnes |first2=L.G. |last3=Ray |first3=C.E. |title=The early Miocene littoral ursoid carnivoran ''Kolponomos'': Systematics and mode of life |year=1994 |journal=Proceedings of the San Diego Society of Natural History |volume=29 |pages=11–32 |url=https://www.biodiversitylibrary.org/pdf1/000389400021705.pdf |archive-url=https://web.archive.org/web/20120922142556/http://www.biodiversitylibrary.org/pdf1/000389400021705.pdf  |archive-date=2012-09-22 |df=dmy-all}}</ref> are known from the Oligocene, including ''[[Amphicticeps]]'' and ''[[Amphicynodon]]''.<ref name=Wang2/> There has been various morphological evidence linking amphicynodontines with [[pinniped]]s, as both groups were semi-aquatic, otter-like mammals.<ref name="Tedfordetal">{{Cite journal |last1=Tedford |first1=R.H. |author-link=Richard H. Tedford |last2=Barnes |first2=L.G. |last3=Ray |first3=C.E. |title=The early Miocene littoral ursoid carnivoran ''Kolponomos'': Systematics and mode of life |year=1994 |journal=Proceedings of the San Diego Society of Natural History |volume=29 |pages=11–32 |url=https://www.biodiversitylibrary.org/pdf1/000389400021705.pdf |archive-url=https://web.archive.org/web/20120922142556/http://www.biodiversitylibrary.org/pdf1/000389400021705.pdf  |archive-date=22 September 2012 |access-date=24 July 2010}}</ref><ref name=Rybczynski07>{{cite journal |last1=Rybczynski |first1=N. |last2=Dawson |first2=M.R. |last3=Tedford |first3=R.H. |year=2009 |title=A semi-aquatic Arctic mammalian carnivore from the Miocene epoch and origin of Pinnipedia |journal=Nature |volume=458 |issue=7241 |pages=1021–1024 |doi=10.1038/nature07985 |pmid=19396145|bibcode=2009Natur.458.1021R|s2cid=4371413 }}</ref><ref name=Berta2018>{{cite journal |last1=Berta |first1=A. |last2=Morgan |first2=C. |last3=Boessenecker |first3=R.W. |year=2018 |title=The Origin and Evolutionary Biology of Pinnipeds: Seals, Sea Lions, and Walruses |journal=Annual Review of Earth and Planetary Sciences |volume=46 |pages=203–228 |doi=10.1146/annurev-earth-082517-010009 |bibcode=2018AREPS..46..203B|s2cid=135439365 |doi-access=free }}</ref> In addition to the support of the pinniped–amphicynodontine clade, other morphological and some molecular evidence supports bears being the closest living relatives to pinnipeds.<ref>{{cite journal |last1=Hunt |first1=R.M. Jr. |last2=Barnes |first2=L.G. |year=1994 |title=Basicranial evidence for ursid affinity of the oldest pinnipeds |journal=Proceedings of the San Diego Society of Natural History |volume=29 |pages=57–67 |url=https://archive.org/details/cbarchive_36692_basicranialevidenceforursidaff1990 |format=PDF}}</ref><ref>{{cite journal |last1=Lento |first1=G.M. |last2=Hickson |first2=R.E. |last3=Chambers |first3=G.K. |last4=Penny |first4=D. |year=1995 |title=Use of spectral analysis to test hypotheses on the origin of pinnipeds |journal=Molecular Biology and Evolution |volume=12 |issue=1 |pages=28–52 |pmid=7877495 |doi=10.1093/oxfordjournals.molbev.a040189 |df=dmy-all |doi-access=free }}</ref><ref name="wangetal2005">{{Cite journal |last1=Wang |first1=X. |last2=McKenna |first2=M.C. |last3=Dashzeveg |first3=D. |title=''Amphicticeps'' and ''Amphicynodon'' (Arctoidea, Carnivora) from Hsanda Gol Formation, central Mongolia and phylogeny of basal arctoids with comments on zoogeography. |doi=10.1206/0003-0082(2005)483[0001:AAAACF]2.0.CO;2 |journal=American Museum Novitates |issue=3483 |year=2005|pages=1–58 |hdl=2246/5674 |s2cid=59126616 |url=https://zenodo.org/record/4735171 }}</ref><ref name=Rybczynski07/><ref name="Higdon 2007">{{Cite journal |last1=Higdon |first1=J.W. |last2=Bininda-Emonds |first2=O.R. |last3=Beck |first3=R.M. |last4=Ferguson |first4=S.H. |title=Phylogeny and divergence of the pinnipeds (Carnivora: Mammalia) assessed using a multigene dataset |doi=10.1186/1471-2148-7-216 |journal=BMC Evolutionary Biology |volume=7 |page=216 |year=2007 |issue=1 |pmid=17996107 |pmc=2245807 |doi-access=free |bibcode=2007BMCEE...7..216H }}</ref><ref name=Berta2018/>
[[File:Arctotherium.jpg|thumb|right|Life restoration of ''Arctotherium bonariense'']]
The raccoon-sized, dog-like ''[[Cephalogale]]'' is the oldest-known member of the subfamily [[Hemicyoninae]], which first appeared during the middle Oligocene in Eurasia about 30&nbsp;Mya.<ref name=Wang2/> The subfamily includes the younger genera ''[[Phoberocyon]]'' (20–15&nbsp;Mya), and ''[[Plithocyon]]'' (15–7&nbsp;Mya). A ''Cephalogale''-like species gave rise to the genus ''[[Ursavus]]'' during the early Oligocene (30–28&nbsp;Mya); this genus proliferated into many species in Asia and is ancestral to all living bears. Species of ''Ursavus'' subsequently entered North America, together with ''Amphicynodon'' and ''Cephalogale'', during the early Miocene (21–18&nbsp;Mya). Members of the living lineages of bears diverged from ''Ursavus'' between 15 and 20&nbsp;Mya,<ref>{{cite journal |last1=Waits |first1=Lisette |title=Rapid radiation events in the family Ursidae indicated by likelihood phylogenetic estimation from multiple fragments of mtDNA |journal=Molecular Phylogenetics and Evolution |date=1999 |volume=13 |issue=1 |pages=82–92 |url=http://dobzhanskycenter.bio.spbu.ru/pdf/sjop/MS298_Waits_MolPhylogenetEvol.pdf |archive-url=https://web.archive.org/web/20150903211855/http://dobzhanskycenter.bio.spbu.ru/pdf/sjop/MS298_Waits_MolPhylogenetEvol.pdf  |archive-date=2015-09-03 |df=dmy-all |doi=10.1006/mpev.1999.0637 |pmid=10508542 |bibcode=1999MolPE..13...82W }}</ref><ref>{{cite journal |last1=Pàges |first1=Marie |title=Combined analysis of fourteen nuclear genes refines the Ursidae phylogeny | journal=Molecular Phylogenetics and Evolution |date=2008 |volume=47 |issue=1 |pages=73–83 |doi=10.1016/j.ympev.2007.10.019 |pmid=18328735|bibcode=2008MolPE..47...73P }}</ref> likely via the species ''Ursavus elmensis''. Based on genetic and morphological data, the Ailuropodinae (pandas) were the first to diverge from other living bears about 19&nbsp;Mya, although no fossils of this group have been found before about 11 Mya.<ref name="krause2008">{{Cite journal |last=Krause |first=J. |author2=Unger, T. |author3=Noçon, A. |author4=Malaspinas, A. |author5=Kolokotronis, S. |author6=Stiller, M. |author7=Soibelzon, L. |author8=Spriggs, H. |author9=Dear, P. H. |author10=Briggs, A. W. |author11=Bray, S.C.E. |author12=O'Brien, S.J. |author13=Rabeder, G. |author14=Matheus, P. |author15=Cooper, A. |author16=Slatkin, M. |author17=Pääbo, S. |author18=Hofreiter, M. |display-authors=6 |title=Mitochondrial genomes reveal an explosive radiation of extinct and extant bears near the Miocene-Pliocene boundary |journal=BMC Evolutionary Biology |volume=8 |issue=220 |page=220 |year=2008 |pmid=18662376 |pmc=2518930 |doi=10.1186/1471-2148-8-220 |doi-access=free |bibcode=2008BMCEE...8..220K }}</ref><ref>{{cite journal|display-authors=3|first1=Juan|last1=Abella|first2=David M.|last2=Alba|first3=Josep M.|last3=Robles|first4=Alberto|last4=Valenciano|first5=Cheyenn|last5=Rotgers|first6=Raül |last6=Carmona|first7=Plinio|last7=Montoya|first8=JorgeZ|last8=Morales|title=Kretzoiarctos gen. nov., the Oldest Member of the Giant Panda Clade|journal=PLOS ONE |year=2012 |volume=7 |issue=11 |pages=e48985 |doi=10.1371/journal.pone.0048985|pmid=23155439 |pmc=3498366 |bibcode=2012PLoSO...748985A |doi-access=free }}</ref>

The New World short-faced bears (Tremarctinae) differentiated from Ursinae following a dispersal event into North America during the mid-Miocene (about 13&nbsp;Mya).<ref name=krause2008/> They [[Great American Interchange|invaded South America]] (≈2.5 or 1.2&nbsp;Ma) following formation of the [[Isthmus of Panama]].<ref>{{cite journal |last1=Soibelzon |first1=L. H. |last2=Tonni |first2=E.P. |last3=Bond |first3=M. |title=The fossil record of South American short-faced bears (Ursidae, Tremarctinae) |journal=Journal of South American Earth Sciences |volume=20 |issue=1–2 |pages=105–113 |year=2005 |doi=10.1016/j.jsames.2005.07.005| hdl=10915/5366 | bibcode=2005JSAES..20..105S |url=http://sedici.unlp.edu.ar/bitstream/handle/10915/5366/Documento_completo.pdf?sequence=1}}</ref> Their earliest fossil representative is ''[[Plionarctos]]'' in North America (c.&nbsp;10–2&nbsp;Ma). This genus is probably the direct ancestor to the [[Arctodus|North American short-faced bears]] (genus ''Arctodus''), the [[Arctotherium|South American short-faced bears]] (''Arctotherium''), and the spectacled bears, ''Tremarctos'', represented by both an extinct North American species (''[[Tremarctos floridanus|T. floridanus]]''), and the lone surviving representative of the Tremarctinae, the South American [[spectacled bear]] (''T. ornatus'').<ref name=Wang2/>

[[File:Teufelshöhle-Höhlenbär-Dreiviertelprofil.jpg|thumb|Fossil of the [[cave bear]] (''Ursus spelaeus''), a relative of the brown bear and polar bear from the [[Pleistocene]] [[Epoch (geology)|epoch]] in Europe]]
The subfamily Ursinae experienced a dramatic proliferation of taxa about 5.3–4.5&nbsp;Mya, coincident with major environmental changes; the first members of the genus ''[[Ursus (genus)|Ursus]]'' appeared around this time. The [[sloth bear]] is a modern survivor of one of the earliest lineages to diverge during this radiation event (5.3&nbsp;Mya); it took on its peculiar morphology, related to its diet of termites and ants, no later than by the early Pleistocene. By 3–4&nbsp;Mya, the species ''Ursus minimus'' appears in the fossil record of Europe; apart from its size, it was nearly identical to today's [[Asian black bear]]. It is likely ancestral to all bears within Ursinae, perhaps aside from the sloth bear. Two lineages evolved from ''U.&nbsp;minimus'': the black bears (including the [[sun bear]], the Asian black bear, and the [[American black bear]]); and the brown bears (which includes the [[polar bear]]). Modern [[brown bear]]s evolved from ''U.&nbsp;minimus'' via ''[[Ursus etruscus]]'', which itself is ancestral to the extinct [[Pleistocene]] [[cave bear]].<ref name=krause2008/> Species of Ursinae have migrated repeatedly into North America from Eurasia as early as 4 Mya during the early Pliocene.<ref name=Qiu>{{cite journal |author=Qiu Zhanxiang |year=2003 |title=Dispersals of Neogene Carnivorans between Asia and North America |journal=Bulletin of the American Museum of Natural History |issue=279 |pages=18–31 |url=http://digitallibrary.amnh.org/dspace/bitstream/2246/447/25/B279a02.pdf |doi=10.1206/0003-0090(2003)279<0018:C>2.0.CO;2 |volume=279 |s2cid=88183435 |archive-url=https://web.archive.org/web/20090326201351/http://digitallibrary.amnh.org/dspace/bitstream/2246/447/25/B279a02.pdf |archive-date=26 March 2009 |url-status=live }}</ref><ref>{{Harvnb|Ward|Kynaston|1995|pp=74–77}}</ref> The polar bear is the most recently evolved species and descended from a population of brown bears that became isolated in northern latitudes by glaciation 400,000&nbsp;years ago.<ref name="Liu et al 2014">{{cite journal |last1=Liu |first1=Shiping |last2=Lorenzen |first2=Eline D. |last3=Fumagalli |first3=Matteo |last4=Li |first4=Bo |last5=Harris |first5=Kelley |last6=Xiong |first6=Zijun |last7=Zhou |first7=Long |last8=Korneliussen |first8=Thorfinn Sand|last9=Somel |first9=Mehmet |last10=Babbitt |first10=Courtney |last11=Wray |first11=Greg |last12=Li |first12=Jianwen |last13=He |first13=Weiming |last14=Wang |first14=Zhuo |last15=Fu |first15=Wenjing |last16=Xiang |first16=Xueyan |last17=Morgan |first17=Claire C. |last18=Doherty |first18=Aoife |last19=O'Connell |first19=Mary J. |last20=McInerney |first20=James O. |last21=Born |first21=Erik W. |last22=Dalén |first22=Love |last23=Dietz |first23=Rune |last24=Orlando |first24=Ludovic |last25=Sonne |first25=Christian |last26=Zhang |first26=Guojie |last27=Nielsen |first27=Rasmus |last28=Willerslev |first28=Eske |last29=Wang |first29=Jun |display-authors=6 |title=Population genomics reveal recent speciation and rapid evolutionary adaptation in Polar Bears |journal=Cell |date=2014 |volume=157 |issue=4 |pages=785–794 |doi=10.1016/j.cell.2014.03.054 |pmid=24813606 |pmc=4089990}}</ref>