Editing Canidae (section)

==Evolution==
{{see also|Caninae#Phylogenetic relationships}}
[[File:Hesperocyoninae, Borophaginae & Caninae.jpg|thumb|right|Representatives of three canid subfamilies: ''[[Hesperocyon]]'' (Hesperocyoninae), ''[[Aelurodon]]'' (Borophaginae) and ''[[Canis aureus]]'' (Caninae)]]
The Canidae are a diverse group of some 37 species ranging in size from the maned wolf with its long limbs to the short-legged bush dog. Modern canids inhabit forests, tundra, savannas, and deserts throughout tropical and temperate parts of the world. The evolutionary relationships between the species have been studied in the past using [[Morphology (biology)|morphological]] approaches, but more recently, molecular studies have enabled the investigation of [[phylogenetics]] relationships. In some species, [[genetic divergence]] has been suppressed by the high level of [[gene flow]] between different populations and where the species have hybridized, large [[hybrid zone]]s exist.<ref name=Wayne>{{cite web |url=http://wooferhouse.net/Links/MolecularEvolutionOfTheDogFamily/MolecularEvolutionOfTheDogFamily.htm |title=Molecular evolution of the dog family |author=Wayne, Robert K. |access-date=27 May 2014}}</ref>

===Eocene epoch===
[[Carnivora]]ns evolved after the [[Cretaceous-Paleogene extinction event|extinction]] of the non-avian dinosaurs 66 million years ago. Around 50 million years ago, or earlier, in the [[Paleocene]], the Carnivora split into two main divisions: [[caniform]] (dog-like) and [[feliform]] (cat-like). By 40 Mya, the first identifiable member of the dog family had arisen. Named ''[[Prohesperocyon]] wilsoni'', its fossils have been found in southwest Texas. The chief features which identify it as a canid include the loss of the upper third molar (part of a trend toward a more shearing bite), and the structure of the middle ear which has an enlarged [[Tympanic part of the temporal bone|bulla]] (the hollow bony structure protecting the delicate parts of the ear). ''Prohesperocyon'' probably had slightly longer limbs than its predecessors, and also had parallel and closely touching toes which differ markedly from the splayed arrangements of the digits in [[bear]]s.<ref name=Wang-Tedford>{{cite magazine| last = Wang| first = Xiaoming| year = 2008| title = How Dogs Came to Run the World|magazine=Natural History Magazine| volume = July/August| url = http://www.naturalhistorymag.com/features/15771/how-dogs-came-to-run-the-world| access-date = 24 May 2014 }}</ref>

Canidae soon divided into three subfamilies, each of which diverged during the Eocene: [[Hesperocyoninae]] (about 39.74–15 Mya), [[Borophaginae]] (about 34–32 Mya), and [[Caninae]] (about 34–30 Mya; the only surviving subfamily). Members of each subfamily showed an [[Cope's rule|increase in body mass with time]] and some exhibited specialized [[hypercarnivorous]] diets that made them prone to extinction.<ref>{{cite journal | first1 = B.| last2 = Wang| last1 = Van Valkenburgh | first2 = X. | first3 = J. | title=Cope's Rule, Hypercarnivory, and Extinction in North American Canids| last3 = Damuth | s2cid = 12017658| journal=Science | volume=306| issue = #5693 | pages=101–104 | date=October 2004 | issn = 0036-8075| pmid = 15459388 | doi=10.1126/science.1102417|bibcode = 2004Sci...306..101V }}</ref>{{rp|Fig. 1}}

===Oligocene epoch===
By the [[Oligocene]], all three subfamilies (Hesperocyoninae, Borophaginae, and Caninae) had appeared in the fossil record of North America. The earliest and most primitive branch of the Canidae was Hesperocyoninae, which included the coyote-sized ''[[Mesocyon]]'' of the Oligocene (38–24 Mya). These early canids probably evolved for the fast pursuit of prey in a grassland habitat; they resembled modern [[viverrid]]s in appearance. Hesperocyonines eventually became extinct in the middle Miocene. One of the early Hesperocyonines, the genus ''[[Hesperocyon]]'', gave rise to ''[[Archaeocyon]]'' and ''[[Leptocyon]]''. These branches led to the borophagine and canine [[evolutionary radiation|radiations]].<ref name=Gittleman>Martin, L.D. 1989. Fossil history of the terrestrial carnivora. Pages&nbsp;536–568 in J.L. Gittleman, editor. Carnivore Behavior, Ecology, and Evolution, Vol. 1. Comstock Publishing Associates: Ithaca.</ref>

===Miocene epoch===
Around 8 Mya, the [[Beringia]]n land bridge allowed members of the genus ''[[Eucyon]]'' a means to enter Asia from North America and they continued on to colonize Europe.<ref name=Perini>{{cite journal |author1=Perini, F. A. |author2=Russo, C. A. M. |author3=Schrago, C. G. |year=2010 |url=https://onlinelibrary.wiley.com/doi/10.1111/j.1420-9101.2009.01901.x|title=The evolution of South American endemic canids: a history of rapid diversification and morphological parallelism |journal=Journal of Evolutionary Biology |volume=23 |issue=#2 |pages=311–322 |doi=10.1111/j.1420-9101.2009.01901.x |pmid=20002250|s2cid=20763999 }}</ref>

===Pliocene epoch===
The ''[[Canis]]'', ''[[Urocyon]]'', and ''[[Vulpes]]'' genera developed from canids from [[North America]], where the canine radiation began. The success of these canids was related to the development of lower [[carnassial]]s that were capable of both [[mastication]] and shearing.<ref name=Gittleman/> Around 5 million years ago, some of the Old World ''[[Eucyon]]'' evolved into the first members of ''Canis'',<ref>{{Cite journal|last1=Perri|first1=Angela R.|last2=Mitchell|first2=Kieren J.|last3=Mouton|first3=Alice|last4=Álvarez-Carretero|first4=Sandra|last5=Hulme-Beaman|first5=Ardern|last6=Haile|first6=James|last7=Jamieson|first7=Alexandra|last8=Meachen|first8=Julie|last9=Lin|first9=Audrey T.|last10=Schubert|first10=Blaine W.|last11=Ameen|first11=Carly|date=2021-01-13|title=Dire wolves were the last of an ancient New World canid lineage|url=https://www.nature.com/articles/s41586-020-03082-x|journal=Nature|volume=591|issue=7848|language=en|pages=87–91|doi=10.1038/s41586-020-03082-x|pmid=33442059|bibcode=2021Natur.591...87P|s2cid=231604957 |issn=1476-4687}}</ref> In the [[Pliocene]], around 4–5 Mya, ''[[Canis lepophagus]]'' appeared in North America. This was small and sometimes coyote-like. Others were wolf-like. ''C. latrans'' (the coyote) is theorized to descend from ''C. lepophagus''.<ref>Nowak, R.M. 1979. North American Quaternary Canis. Monograph of the Museum of Natural History, University of Kansas 6:1 – 154.</ref>

The formation of the [[Isthmus of Panama]], about 3 Mya, joined [[South America]] to North America, allowing canids to [[Great American Interchange|invade South America]], where they diversified. However, the last common ancestor of the South American canids lived in North America some 4 Mya and more than one incursion across the new land bridge is likely given the fact that more than one lineage is present in South America. Two North American lineages found in South America are the [[gray fox]] (''Urocyon cinereoargentus'') and the now-extinct [[dire wolf]] (''Aenocyon dirus''). Besides these, there are species endemic to South America: the [[maned wolf]] (''Chrysocyon brachyurus''), the [[short-eared dog]] (''Atelocynus microtis''), the [[bush dog]] (''Speothos venaticus''), the [[crab-eating fox]] (''Cerdocyon thous''), and the [[South American fox]]es (''Lycalopex'' [[spp.]]). The monophyly of this group has been established by molecular means.<ref name=Perini/>

===Pleistocene epoch===
During the [[Pleistocene]], the North American wolf line appeared, with ''[[Canis edwardii]]'', clearly identifiable as a wolf, and ''[[Canis rufus]]'' appeared, possibly a direct descendant of ''C.&nbsp;edwardii''. Around 0.8&nbsp;Mya, ''[[Canis ambrusteri]]'' emerged in North America. A large wolf, it was found all over North and Central America and was eventually supplanted by the dire wolf, which then spread into South America during the Late Pleistocene.<ref name=Larson>{{cite web |author=Larson, Robert |title=Wolves, coyotes and dogs (Genus ''Canis'') |series=The Midwestern United States 16,000&nbsp;years ago |publisher=Illinois State Museum |url=http://exhibits.museum.state.il.us/exhibits/larson/canis.html |access-date=7 June 2014}}</ref>

By 0.3 Mya, a number of subspecies of the gray wolf (''C.&nbsp;lupus'') had developed and had spread throughout Europe and northern Asia.<ref>{{cite journal |author=Nowak, R. |year=1992 |title=Wolves: The great travelers of evolution |journal=International Wolf |volume=2 |issue=4 |pages=3–7}}</ref> The gray wolf colonized North America during the late [[Rancholabrean]] era across the Bering land bridge, with at least three separate invasions, with each one consisting of one or more different Eurasian gray wolf clades.<ref name=Chambers>{{cite journal |author1=Chambers, S.M. |author2=Fain, S.R. |author3=Fazio, B. |author4=Amaral, M. |year=2012 |title=An account of the taxonomy of North American wolves from morphological and genetic analyses |journal=North American Fauna |volume=77 |pages=1–67 |doi=10.3996/nafa.77.0001 |doi-access=free }}</ref> MtDNA studies have shown that there are at least four extant ''C. lupus'' lineages.<ref name="gaubert">{{cite journal|author1=Gaubert, P. |author2=Bloch, C. |author3=Benyacoub, S. |author4=Abdelhamid, A. |author5=Pagani, P. |display-authors=etal |year=2012 |title= Reviving the African Wolf ''Canis lupus lupaster'' in north and west Africa: A mitochondrial lineage ranging more than 6,000&nbsp;km wide |journal=PLOS ONE |volume=7 |issue=8 |page=e42740 |doi=10.1371/journal.pone.0042740 |pmid=22900047 |pmc=3416759 |bibcode=2012PLoSO...742740G|doi-access=free }}</ref> The dire wolf shared its habitat with the gray wolf, but became extinct in a large-scale extinction event that occurred around 11,500&nbsp;years ago. It may have been more of a scavenger than a hunter; its molars appear to be adapted for crushing bones and it may have gone extinct as a result of the extinction of the large herbivorous animals on whose carcasses it relied.<ref name=Larson/>

In 2015, a study of mitochondrial genome sequences and whole-genome nuclear sequences of African and Eurasian canids indicated that extant wolf-like canids have colonized Africa from Eurasia at least five times throughout the Pliocene and Pleistocene, which is consistent with fossil evidence suggesting that much of African canid fauna diversity resulted from the immigration of Eurasian ancestors, likely coincident with Plio-Pleistocene climatic oscillations between arid and humid conditions. When comparing the African and Eurasian golden jackals, the study concluded that the African specimens represented a distinct monophyletic lineage that should be recognized as a separate species, ''Canis anthus'' ([[African golden wolf]]). According to a phylogeny derived from nuclear sequences, the Eurasian golden jackal (''Canis aureus'') diverged from the wolf/coyote lineage 1.9&nbsp;[[MYA (unit)|Mya]], but the African golden wolf separated 1.3&nbsp;Mya. Mitochondrial genome sequences indicated the Ethiopian wolf diverged from the wolf/coyote lineage slightly prior to that.<ref name=Koepfli-2015>{{cite journal  |last1=Koepfli |first1=Klaus-Peter |last2=Pollinger |first2=John |last3=Godinho |first3=Raquel |last4=Robinson |first4=Jacqueline |last5=Lea |first5=Amanda |last6=Hendricks |first6=Sarah |last7=Schweizer |first7=Rena M. |last8=Thalmann |first8=Olaf |last9=Silva |first9=Pedro |last10=Fan |first10=Zhenxin |last11=Yurchenko |first11=Andrey A. |last12=Dobrynin |first12=Pavel |last13=Makunin |first13=Alexey |last14=Cahill |first14=James A. |last15=Shapiro |first15=Beth |last16=Álvares |first16=Francisco |last17=Brito |first17=José C. |last18=Geffen |first18=Eli |last19=Leonard |first19=Jennifer A. |last20=Helgen |first20=Kristofer M. |last21=Johnson |first21=Warren E. |last22=o'Brien |first22=Stephen J. |last23=van Valkenburgh |first23=Blaire |last24=Wayne |first24=Robert K. |display-authors=6  |year=2015 |title=Genome-wide evidence reveals that African and Eurasian golden jackals are distinct species |journal=Current Biology |volume=25 |issue=16 |pages=2158–2165  |pmid=26234211 |doi=10.1016/j.cub.2015.06.060 |doi-access=free|bibcode=2015CBio...25.2158K }}</ref>{{rp|S1}}