View source for Dire wolf

{{Short description|Extinct species of canine mammal}}
{{For-multi|the fictional creature in the A Song of Ice and Fire series|Direwolf (Game of Thrones)||Dire wolf (disambiguation)}}
{{Featured article}}
{{Pp-pc}}
{{Speciesbox
| name = Dire wolf
| fossil_range = {{Fossil range|.125|.01|[[Late Pleistocene]] – early [[Holocene]] (125,000–10,000 years ago)}}{{small|Possible [[Middle Pleistocene]] records}}
| image = Canis dirus Sternberg Museum.jpg
| image_upright = 1.1
| image_caption = Mounted skeleton, [[Sternberg Museum of Natural History]]
| parent_authority = [[John Campbell Merriam|Merriam]], 1918<ref name=merriam1918/>
| display_parents = 4
| genus = Aenocyon
| species = dirus
| authority = ([[Joseph Leidy|Leidy]], 1858)<ref name=leidy1858/>
| extinct = yes <!-- Please DO NOT update to indicate de-extinction until consensus is reached on talk page to do so-->
| subdivision_ranks = Subspecies
| subdivision_ref = <ref name=kurten1984/>
| subdivision = * {{extinct}}''Aenocyon dirus dirus'' <small>([[Joseph Leidy|Leidy]], 1858)</small><ref name=leidy1858/>
* {{extinct}}''Aenocyon dirus guildayi'' <small>([[Björn Kurtén|Kurtén]] 1984)</small><ref name=kurten1984/>
| synonyms = {{smalldiv|
* ''Canis primaevus'' [[Joseph Leidy|Leidy]], 1854<ref name=leidy1854/>
* ''Canis dirus'' [[Joseph Leidy|Leidy]], 1858<ref name=leidy1858/>
* ''Canis indianensis'' [[Joseph Leidy|Leidy]], 1869<ref name=leidy1869/>
* ''Canis mississippiensis''? [[Joel Asaph Allen|Allen]], 1876<ref name=allen1876/>
* ''[[Canis nehringi]]''? [[Florentino Ameghino|Ameghino]], 1902<ref>AMEGHINO, F. 1902. Notas sobre algunos mamíferos
fósiles nuevos ó poco conocidos del valle de Tarija.
Anales del Museo Nacional de Buenos Aires, 3º serie, 1:225–261</ref>
* ''Canis ayersi'' Sellards, 1916<ref name=sellards1916/>
* ''Aenocyon dirus nebrascensis'' Frick, 1930 (''[[nomen nudum]]'')<ref name=frick1930/>
}}
}}

The '''dire wolf''' ('''''Aenocyon dirus'''''<ref>From Greek {{lang|grc|αἰνός}} ({{transliteration|grc|ainós}}) 'dreadful' + {{lang|grc|κύων}} ({{transliteration|grc|kúōn}}) 'dog' and Latin {{lang|la|dīrus}} 'fearsome'</ref> {{IPAc-en|iː|'|n|ɒ|k|aɪ|.|ɒ|n|_|'|d|aɪ|r|ə|s|audio=LL-Q1860 (eng)-Naomi Persephone Amethyst (NaomiAmethyst)-aenocyon dirus.wav}}) is an [[Extinction|extinct]] species<!-- Please DO NOT update to indicate successful de-extinction until this is decided on the talk page and until Colossal's preprint finishes the peer-review process --> of [[Caninae|canine]] which was native to the [[Americas]] during the [[Late Pleistocene]] and Early [[Holocene]] epochs (125,000–10,000 years ago). The species was named in 1858, four years after the first [[Fossil|specimen]] had been found. Two [[subspecies]] are proposed, ''Aenocyon dirus guildayi'' and ''Aenocyon dirus dirus'', but this assignment has been recently considered questionable. The largest collection of its [[fossil]]s has been obtained from the Rancho [[La Brea Tar Pits]] in [[Los Angeles]].

Dire wolf remains have been found across a broad range of habitats including [[plain]]s, [[grassland]]s, and some [[Montane ecosystem|forested mountain]] areas of [[North America]] and the arid [[Savanna#Savanna ecoregions|savanna]] of [[South America]]. The sites range in elevation from [[sea level]] to {{convert|2,255|m|ft|-1|sp=us}}. Dire wolf fossils have rarely been found north of [[42nd parallel north|42°N latitude]]; there have been only five unconfirmed records above this latitude. This range restriction is thought to be due to temperature, prey, or habitat limitations imposed by proximity to the [[Laurentide Ice Sheet|Laurentide]] and [[Cordilleran Ice Sheet|Cordilleran]] ice sheets that existed at the time.

The dire wolf was about the same size as the largest modern forms of [[wolf|gray wolf]] (''Canis lupus''): the [[Interior Alaskan wolf|Yukon wolf]] and the [[northwestern wolf]]. ''A.{{nbsp}}d.{{nbsp}}guildayi'' weighed on average {{convert|60|kg|lb|0}} and ''A.{{nbsp}}d.{{nbsp}}dirus'' was on average {{cvt|68|kg|0}}. Its skull and dentition matched those of ''C.{{nbsp}}lupus'', but its teeth were larger with greater shearing ability, and its bite force at the [[canine tooth]] was stronger than any known ''Canis'' species. These characteristics are thought to be adaptations for preying on Late Pleistocene [[Pleistocene megafauna|megaherbivores]]; in North America, its prey is suggested to have included [[Equus occidentalis|western horse]]s, [[dwarf pronghorn]], [[flat-headed peccary]], [[ground sloth]]s, [[Bison antiquus|ancient bison]], and [[Camelops|camels]]. Dire wolves lived as recently as [[10,000 years ago]], according to dated remains. Its extinction occurred during the [[Quaternary extinction event#North America|Quaternary extinction event]], disappearing along with its main prey species; its reliance on [[Megaherbivore|megaherbivores]] has been proposed as the cause of its extinction, along with [[climate change (general concept)|climatic change]] and [[competition (biology)|competition]] with other species, or a combination of those factors.

==Taxonomy==
From the 1850s, the fossil remains of extinct large wolves were being found in the United States, and it was not immediately clear that these all belonged to one species. The first specimen of what would later become associated with ''Aenocyon dirus'' was found in mid-1854 in the bed of the [[Ohio River]] near [[Evansville, Indiana]]. The fossilized jawbone with cheek teeth was obtained by geologist [[Joseph Granville Norwood]] from an Evansville collector, Francis A. Linck. Paleontologist [[Joseph Leidy]] determined that the specimen represented an extinct species of wolf and reported it under the name of ''Canis primaevus''.<ref name=leidy1854/> Norwood's letters to Leidy are preserved along with the [[type specimen]] (the first of a species that has a written description) at the [[Academy of Natural Sciences of Drexel University|Academy of Natural Sciences of Philadelphia]]. In 1857, while exploring the [[Niobrara River]] valley in Nebraska, Leidy found the vertebrae of an extinct ''Canis'' species that he reported the following year under the name ''C.{{nbsp}}dirus''.<ref name=leidy1858/> The name ''C.{{nbsp}}primaevus'' (Leidy 1854) was later renamed ''Canis indianensis'' (Leidy 1869) when Leidy found out that the name ''C.{{nbsp}}primaevus'' had previously been used by the British naturalist [[Brian Houghton Hodgson]] for the [[dhole]].<ref name=leidy1869/>

[[File:Dire Wolf Skulls La Brea 2005-08-01.JPG|thumb|left|Display at the Page Museum of 404 dire wolf skulls found in the [[La Brea Tar Pits]]<ref name=page/>]]
In 1876, zoologist [[Joel Asaph Allen]] discovered the remains of ''Canis mississippiensis'' (Allen 1876) and associated these with ''C.{{nbsp}}dirus'' (Leidy 1858) and ''Canis indianensis'' (Leidy 1869). As so little was found of these three specimens, Allen thought it best to leave each specimen listed under its provisional name until more material could be found to reveal their relationship.<ref name=allen1876/> In 1908 paleontologist [[John Campbell Merriam]] began retrieving numerous fossilized bone fragments of a large wolf from the Rancho La{{nbsp}}Brea tar pits. By 1912 he had found a skeleton sufficiently complete to be able to formally recognize these and the previously found specimens under the name ''C.{{nbsp}}dirus'' (Leidy 1858). Because the rules of [[nomenclature]] stipulated that the name of a species should be the oldest name ever applied to it,<ref name=iczncode2017/> Merriam therefore selected the name of Leidy's 1858 specimen, ''C.{{nbsp}}dirus''.<ref name=merriam1912/> In 1915 paleontologist Edward Troxell indicated his agreement with Merriam when he declared ''C.{{nbsp}}indianensis'' a synonym of ''C.{{nbsp}}dirus''.<ref name=troxell1915/> In 1918, after studying these fossils, Merriam proposed consolidating their names under the separate genus ''Aenocyon'' (from ''ainos'', 'terrible' and ''cyon'', 'dog') to become ''Aenocyon dirus'',<ref name=merriam1918/> but at that time not everyone agreed with this extinct wolf being placed in a new genus separate from the genus ''Canis''.<ref name=stevenson1978/> ''Canis ayersi'' (Sellards 1916) and ''Aenocyon dirus'' (Merriam 1918) were recognized as synonyms of ''C.{{nbsp}}dirus'' by the paleontologist [[Ernest Lundelius]] in 1972.<ref name=lundelius1972/> All of the above taxa were declared synonyms of ''C.{{nbsp}}dirus'' in 1979, according to the paleontologist Ronald M. Nowak.<ref name=nowak106/> However, Hill et al. (2025) examined the taxonomic history of ''C. mississippiensis'' and directly compared the bones attributed to ''C. mississippiensis'' with those of the Pleistocene gray wolf (''Canis lupus'') and the dire wolf (''Aenocyon dirus''), reaching a conclusion that ''C. mississippiensis'' is most likely synonymous with ''C. lupus''.<ref name=Hill2025/>

In 1984, a study by Finnish paleontologist [[Björn Kurtén]] recognized a geographic variation within the dire wolf populations and proposed two subspecies: ''Canis dirus guildayi'' (named by Kurtén in honor of American paleontologist [[species:John E. Guilday|John E. Guilday]]) for specimens from California and Mexico that exhibited shorter limbs and longer teeth, and ''Canis dirus dirus'' for specimens east of the North American [[Continental Divide of the Americas|Continental Divide]] that exhibited longer limbs and shorter teeth.<ref name=kurten1984/><ref name=wang1990/><ref name=dundas1999/><ref name=anyonge2005a/> Kurtén designated a [[maxilla]] found in Hermit's Cave, New Mexico, as representing the nominate subspecies ''C. d. dirus''.<ref name=kurten1984/> In 2019, this subspecific assignment was questioned by paleontologists Damián Ruiz-Ramoni and Marisol Montellano-Ballesteros at [[National Autonomous University of Mexico]], who were unable to find a significant difference between the specimens assigned to each proposed subspecies.<ref>{{Cite journal|author1=Ruiz-Ramoni, D.|author2=Montellano-Ballesteros, M. |year=2019 |title=Taxonomía y biogeografía del extinto lobo gigante, ''Canis dirus'' Leidy, 1858, en México |journal=Boletín de la Sociedad Geológica Mexicana |volume=71 |issue=1 |pages=121–137 |doi=10.18268/BSGM2019v71n1a7 |bibcode=2019BoSGM..71..121R |doi-access=free }}</ref>

In 2021, a DNA study found the dire wolf to be a highly [[Genetic divergence|divergent]] lineage when compared with the extant [[Canina (subtribe)|wolf-like canines]], and this finding is consistent with the previously proposed taxonomic classification of the dire wolf as genus ''Aenocyon'' (Ancient Greek: "terrible wolf") as proposed by Merriam in 1918.<ref name=Perri2021/>

===Evolution===
The [[Canidae|canid]] family first appears in the North American fossil record around 40&nbsp;million years ago,<ref name=wang20/><ref name=Wang-Tedford_2008/> and the canine subfamily [[Caninae]] about 32&nbsp;million years ago.<ref name=wang49/> From the Caninae, the ancestors of the fox-like [[Vulpini]] and the dog-like [[Canini (tribe)|Canini]] branched off about 9&nbsp;million years ago. The Canini are first represented by ''Eucyon'', and mostly by [[coyote]]-like ''[[Eucyon davisi]]'' that was widely spread across North America.<ref name=tedford4/> From the Canini the [[Cerdocyonina]] developed 6–5&nbsp;million years ago, today represented by their canid descendants distinctly native to South America.<ref name=wang148/> Fossils of its sister clade, the wolf-like [[Canina (subtribe)|Canina]], first appear 5&nbsp;million years ago; however, they are believed to have likely originated as far back as 9&nbsp;million years ago.<ref name=tedford4/> Around 7&nbsp;million years ago, the canines expanded into Eurasia and Africa, with ''Eucyon'' giving rise to the first members of the ''[[Canis]]'' genus in Europe.<ref name=wang143/> Around 4–3&nbsp;million years ago ''[[Evolution of the wolf#Canis chihliensis|C.&nbsp;chihliensis]]'', the first wolf-sized member of ''Canis'', arose in China and radiated into multiple other wolf-like canids across Eurasia and Africa. Members of the genus ''Canis'' later expand back into North America.<ref name=wang148/>

The dire wolf evolved in North America.<ref name=wang148/><ref name=Perri2021/> However, its ancestral lineage is debated, with two competing theories: The first theory is based on fossil [[Morphology (biology)|morphology]], which indicates that an expansion of the genus ''Canis'' out of Eurasia led to the dire wolf.<ref name=wang148/> The second theory is based on DNA evidence, which indicates that the dire wolf arose from an ancestral lineage that originated in the Americas and was separate from the genus ''Canis''.<ref name=Perri2021/>

====Morphological evidence====
{{See also|Evolution of the wolf}}

{{cladogram
|title=Dire wolf divergence based on morphology
|caption=[[Evolutionary divergence]] of the dire wolf based on fossil [[Morphology (biology)|morphology]].<ref name=wang148/><ref name=tedford181/>
|cladogram={{clade
 |style= font-size:85%; line-height:65%; width:450px;
 |label1={{extinct}}''[[Evolution of the wolf#Canis chihliensis|Canis chihliensis]]''
 |1={{clade
    |label1=''[[Canis lupus]]''
    |1={{clade
       |1=[[File:Dogs, jackals, wolves, and foxes (Plate V).png|50 px]]
       }}
    |label2={{extinct}}''[[Canis armbrusteri]]''
    |2={{clade
       |label1={{extinct}}[[Canis nehringi#Canis gezi|''Canis gezi'']]
       |1=[[File:Large sized canid icon.jpg|50 px]]
       |label2={{extinct}}''[[Canis nehringi]]''
       |2=[[File:Large sized canid icon.jpg|50 px]]
       |label3={{extinct}}'''''Canis dirus'''''
       |3={{clade
          |1={{clade
             |label1={{extinct}}'''''Canis dirus''' guildayi''
             |1=[[File:The American Museum journal (c1900-(1918)) (Aenocyon dirus).jpg|50 px]]
             |label2={{extinct}}'''''Canis dirus''' dirus''
             |2=[[File:The American Museum journal (c1900-(1918)) (Aenocyon dirus).jpg|50 px]]
             }}
          }}
       }}
    }}
 }}
}}

<!-- Please do not update this section until the pre-pint finishes peer-review -->Morphological evidence based on fossil remains indicates an expansion of genus ''Canis'' from out of Eurasia led to the dire wolf.<ref name=wang148/><ref name=tedford181/>

In 1974 Robert A. Martin proposed that the large North American wolf ''C.&nbsp;armbrusteri'' (Armbruster's wolf) was ''C.&nbsp;lupus''.<ref name=martin1974/> Nowak, Kurtén, and [[Annalisa Berta]] proposed that ''C.&nbsp;dirus'' was not derived from ''C.&nbsp;lupus''.<ref name=nowak106/><ref name=berta50/><ref name=kurten1980/> In 1987, a new hypothesis proposed that a mammal population could give rise to a larger form called a hypermorph during times when food was abundant, but when food later became scarce the hypermorph would either adapt to a smaller form or go extinct. This hypothesis might explain the large body sizes found in many Late Pleistocene mammals compared to their modern counterparts. Both extinction and [[speciation]]{{snd}}a process by which a new species splits from an older one{{snd}}could occur together during periods of climatic extremes.<ref name=geist1998/><ref name=geist1987/> Gloria D. Goulet agreed with Martin, proposing further that this hypothesis might explain the sudden appearance of ''C.&nbsp;dirus'' in North America and, judging from the similarities in their skull shapes, that ''C.&nbsp;lupus'' had given rise to the ''C.&nbsp;dirus'' hypermorph due to an abundance of game, a stable environment, and large competitors.<ref name=goulet1993/>

The three paleontologists [[Xiaoming Wang (paleontologist)|Xiaoming Wang]], [[Richard H. Tedford]], and Ronald M. Nowak propose that ''C.&nbsp;dirus'' evolved from ''Canis armbrusteri'',<ref name=wang148/><ref name=tedford181/> with Nowak stating that both species arose in the Americas<ref name=nowak102/> and that specimens found in [[Cumberland Bone Cave|Cumberland Cave, Maryland]], appear to be ''C.&nbsp;armbrusteri'' diverging into ''C.&nbsp;dirus''.<ref name=nowak2002/><ref name=nowak2003/> Nowak believed that ''[[Canis edwardii]]'' was the first appearance of the wolf in North America, and it appears to be close to the lineage which produced ''C.&nbsp;armbrusteri'' and ''C.&nbsp;dirus''.<ref name=nowak84/> Tedford believes that the early wolf from China, ''[[Evolution of the wolf#Canis chihliensis|Canis chihliensis]]'', may have been the ancestor of both ''C.&nbsp;armbrusteri'' and the [[gray wolf]] ''C.&nbsp;lupus''.<ref name=tedford146/> The sudden appearance of ''C.&nbsp;armbrusteri'' in mid-latitude North America during the [[Early Pleistocene]] 1.5&nbsp;million years ago, along with the mammoth, suggests that it was an immigrant from Asia,<ref name=tedford181/> with the gray wolf ''C.&nbsp;lupus'' evolving in Beringia later in the [[Pleistocene]] and entering mid-latitude North America during the [[Last Glacial Period]] along with its Beringian prey.<ref name=wang148/><ref name=tedford181/><ref name=nowak2003/> In 2010 Francisco Prevosti proposed that ''C.&nbsp;dirus'' was a [[sister taxon]] to ''C.&nbsp;lupus''.<ref name=prevosti2010/>

[[File:The American Museum journal (c1900-(1918)) (17537635834).jpg|thumb|left|[[Life restoration]] by [[Erwin S. Christman]], 1916]]
''C.&nbsp;dirus'' lived in the Late Pleistocene to the early [[Holocene]], 125,000–10,000&nbsp;[[YBP]] ([[years before present]]), in North and South America.<ref name=kurten1984/> The majority of fossils from the eastern ''C.&nbsp;d.&nbsp;dirus'' have been dated 125,000–75,000&nbsp;YBP, but the western {{nobr|''C. d. guildayi''}} fossils are not only smaller in size but more recent; thus it has been proposed that {{nobr|''C. d. guildayi''}} derived from {{nobr|''C. d. dirus''.}}<ref name=kurten1984/><ref name=anyonge2005a/> However, there are disputed specimens of ''C.&nbsp;dirus'' that date to 250,000&nbsp;YBP. Fossil specimens of ''C.&nbsp;dirus'' discovered at four sites in the [[Hay Springs, Nebraska|Hay Springs]] area of [[Sheridan County, Nebraska]], were named ''Aenocyon dirus nebrascensis'' (Frick 1930, undescribed), but Frick did not publish a description of them. Nowak later referred to this material as ''C.&nbsp;armbrusteri'';<ref name=nowak93/> then, in 2009, Tedford formally published a description of the specimens and noted that, although they exhibited some morphological characteristics of both ''C.&nbsp;armbrusteri'' and ''C.&nbsp;dirus'', he referred to them only as ''C.&nbsp;dirus''.<ref name=tedford146/>

A fossil discovered in the Horse Room of the Salamander Cave in the [[Black Hills]] of South Dakota may possibly be ''C.&nbsp;dirus''; if so, this fossil is one of the earliest specimens on record.<ref name=dundas1999/><ref name=lundelius2004/> It was catalogued as ''Canis cf. C.&nbsp;dirus''<ref name=mead1996/> (where [[Open nomenclature#Usage of open nomenclature|cf.]] in Latin means confer, uncertain). The fossil of a horse found in the Horse Room provided a [[Uranium-thorium dating|uranium-series dating]] of 252,000&nbsp;[[YBP]] and the ''Canis cf. dirus'' specimen was assumed to be from the same period.<ref name=dundas1999/><ref name=mead1996/> ''C.&nbsp;armbrusteri'' and ''C.&nbsp;dirus'' share some characteristics ([[synapomorphies]]) that imply the latter's descent from the former. The fossil record suggests ''C.&nbsp;dirus'' originated around 250,000&nbsp;YBP in the open terrain of the mid-continent before expanding eastward and displacing its ancestor ''C.&nbsp;armbrusteri''.<ref name=tedford181/> The first appearance of ''C.&nbsp;dirus'' would therefore be 250,000&nbsp;YBP in California and Nebraska, and later in the rest of the United States, Canada, Mexico, Venezuela, Ecuador, Bolivia, and Peru,<ref name=tedford146/> but the identity of these earliest fossils is not confirmed.<ref name=meachen2016/>

In South America, ''C.&nbsp;dirus'' specimens dated to the Late Pleistocene were found along the north and west coasts, but none have been found in Argentina, an area that was inhabited by ''[[Canis nehringi#Canis gezi|Canis gezi]]'' and ''[[Canis nehringi]]''.<ref name=tedford146/> Given their similarities and timeframes, it is proposed that ''C.&nbsp;gezi'' was the ancestor of ''Canis nehringi''. One study found that ''C.&nbsp;dirus'' was more [[Synapomorphy|evolutionarily derived]] than ''C.&nbsp;nehringi'', and was larger in the size and construction of its lower molars for more efficient predation.<ref name=berta113/> For this reason, some researchers have proposed that ''C.&nbsp;dirus'' may have originated in South America.<ref name=nowak116/><ref name=dundas1999/><ref name=kurten1980/> Tedford proposed that ''C.&nbsp;armbrusteri'' was the common ancestor for both the North and South American wolves.<ref name=tedford146/> Later studies suggested that ''C.&nbsp;dirus'' and ''C.&nbsp;nehringi'' were the same species,<ref name=prevosti2010/><ref name=Zrzavy2018/> though this possible synonymy is not officially formalized yet,<ref name=RR2022/> and that ''C.&nbsp;dirus'' had migrated from North America into South America, making it a participant in the [[Great American Interchange]].<ref name=prevosti2010/> In 2018, a study found that ''Canis gezi'' did not fall under genus ''Canis'' and should be classified under the subtribe [[Cerdocyonina]]; however, no genus was proposed.<ref name=Zrzavy2018/>

The 2020 discovery of a claimed dire wolf fossil in northeast China indicates that dire wolves may have crossed [[Beringia]] when it existed,<ref name=Lu2020/> though Ruiz-Ramoni et al. (2022) doubted that this specimen represents a dire wolf.<ref name=RR2022/> They also proposed that the Armbruster's wolf should be given a new genus name, possibly included within the genus ''Aenocyon'', as it was probably ancestral to the dire wolf and its assignment within the genus ''Canis'' is not well-founded.<ref name=RR2022/> This was also considered plausible by other authors.<ref>{{Cite journal|last1=Bartolini-Lucenti |first1=S. |last2=Cirilli |first2=O. |last3=Melchionna |first3=M. |last4=Raia |first4=P. |last5=Tseng |first5=Z. J. |last6=Flynn |first6=J. J. |last7=Rook |first7=L. |year=2024 |title=Virtual reconstruction of the ''Canis arnensis'' type (Canidae, Mammalia) from the Upper Valdarno Basin (Italy, Early Pleistocene) |journal=Scientific Reports |volume=14 |issue=1 |at=8303 |doi=10.1038/s41598-024-53073-5 |pmid=38594298 |pmc=11004169 |doi-access=free |bibcode=2024NatSR..14.8303B }}</ref> In their revision of the Pleistocene assemblage from the [[Cumberland Bone Cave]], Eshelman et al. (2025) proposed the new combination of the Armbruster's wolf within the genus ''Aenocyon'' (''A. armbrusteri''), which would expand the earliest known occurrence of this genus up to the [[Middle Pleistocene]].<ref>{{Cite journal|last1=Eshelman |first1=R. E. |last2=Bell |first2=C. J. |last3=Graham |first3=R. W. |last4=Semken |first4=H. A. |last5=Withnell |first5=C. B. |last6=Scarpetta |first6=S. G. |last7=James |first7=H. F. |last8=Godfrey |first8=S. J. |last9=Mead |first9=J. I. |last10=Hodnett |first10=J.-P. |last11=Grady |first11=F. V. |year=2025 |title=Middle Pleistocene Cumberland Bone Cave Local Fauna, Allegany County, Maryland: A Systematic Revision and Paleoecological Interpretation of the Irvingtonian, Middle Appalachians, USA |journal=Smithsonian Contributions to Paleobiology |volume=108 |pages=1–305 |doi=10.5479/si.28597193 |doi-access=free }}</ref>

====DNA evidence====
{{Cladogram
|title=[[Cladogram]] showing relationships among living and extinct wolf-like canids based on DNA{{efn|group=note
|The cladogram below is based on Perri 2021<ref name=Perri2021/> modified to incorporate recent findings on ''[[Canis]]'' species,<ref name=Koepfli2015/> and the renaming of the African jackals as genus ''[[Lupulella]]''.<ref name=Alvares2019/>
}}
|caption=Based on [[Nuclear DNA|nDNA]] data indicating that the dire wolf branched 5.7&nbsp;million years ago<ref name=Perri2021/>
|cladogram={{clade
  |style=font-size:75%; line-height:65%;width:450px;
  |label1=[[Canini (tribe)|Canini]]
  |1={{clade
     |2={{clade
        |label1={{extinct}}''[[Aenocyon]]''
        |1=<br /><br />{{extinct}}'''''Aenocyon dirus''''' ('''dire wolf''') [[File:The American Museum journal (c1900-(1918)) (Aenocyon dirus) Lupified version.png|100 px]]
        }}
     |label1=
     |1={{clade
        |label1=
        |2={{clade
           |label1= ''[[Lupulella]]'' 
           |1=<br /><br />(African [[jackal]]s) [[File:Dogs, jackals, wolves, and foxes (Plate XII).jpg|80 px]]
           }}
        |1={{clade
           |label1=
           |1={{clade
              |label1= ''[[Canis]]''
              |1=([[Grey wolf|wolves]], [[dog]]s, Eurasian [[jackal]]s, etc.) [[File:Dogs, jackals, wolves, and foxes (Plate X).png|80 px]]
              |label2= ''[[Cuon]]''
              |2=<br /><br />''Cuon alpinus'' ([[dhole]])[[File:Dogs, jackals, wolves, and foxes (Plate XLI).png|80 px]]
              }}
           |2={{clade
              |label1= ''[[Lycaon (genus)|Lycaon]]''
              |1=''Lycaon pictus'' ([[African wild dog]]) [[File:Dogs, jackals, wolves, and foxes (Plate XLIV).png|80 px]]
              }}
           }}
        }}
     }}
  }}
}}

DNA evidence indicates the dire wolf arose from an ancestral lineage that originated in the Americas and was separate to genus ''Canis''.<ref name=Perri2021/>

In 1992 an attempt was made to extract a [[mitochondrial DNA]] sequence from the skeletal remains of ''A.{{nbsp}}d.{{nbsp}}guildayi'' to compare its relationship to other ''Canis'' species. The attempt was unsuccessful because these remains had been removed from the La{{nbsp}}Brea pits and tar could not be removed from the bone material.<ref name=janczewski1992/> In 2014 an attempt to extract DNA from a [[Columbian mammoth]] from the [[tar pits]] also failed, with the study concluding that organic compounds from the asphalt permeate the bones of all ancient samples from the La{{nbsp}}Brea pits, hindering the extraction of DNA samples.<ref name=gold2014/>

In 2021, researchers sequenced the [[nuclear DNA]] (from the cell nucleus) taken from five dire wolf fossils dating from 13,000 to 50,000&nbsp;years ago. The sequences indicate the dire wolf to be a highly divergent lineage which last shared a [[most recent common ancestor]] with the wolf-like canines 5.7&nbsp;million years ago. The study also measured numerous dire wolf and gray wolf skeletal samples that showed their morphologies to be highly similar, which had led to the theory that the dire wolf and the gray wolf had a close evolutionary relationship. The morphological similarity between dire wolves and gray wolves was concluded to be due to [[convergent evolution]]. Members of the wolf-like canines are known to hybridize with each other but the study could find no indication of [[genetic admixture]] from the five dire wolf samples with extant North American gray wolves and coyotes nor their common ancestor. This finding indicates that the wolf and coyote lineages evolved in isolation from the dire wolf lineage.<ref name=Perri2021/>

The study proposes an early origin of the dire wolf lineage in the Americas, and that this geographic isolation allowed them to develop a degree of [[reproductive isolation]] since their divergence 5.7&nbsp;million years ago. Coyotes, dholes, gray wolves, and the extinct ''[[Xenocyon]]'' evolved in Eurasia and expanded into North America relatively recently during the Late Pleistocene, therefore there was no admixture with the dire wolf. The long-term isolation of the dire wolf lineage implies that other American fossil taxa, including ''[[Armbruster's wolf|C.&nbsp;armbrusteri]]'' and ''[[Canis edwardii|C.&nbsp;edwardii]]'', may also belong to the dire wolf's lineage. The study's findings are consistent with the previously proposed taxonomic classification of the dire wolf as genus ''Aenocyon''.<ref name=Perri2021/>

===Radiocarbon dating===
The age of most dire wolf localities is determined solely by [[biostratigraphy]], but biostratigraphy is an unreliable indicator within asphalt deposits.<ref name=stock1992/><ref name=okeefe2009/> Some sites have been [[Radiocarbon dating|radiocarbon dated]], with dire wolf specimens from the La{{nbsp}}Brea pits dated in calendar years as follows: 82 specimens dated 13,000–14,000{{nbsp}}YBP; 40 specimens dated 14,000–16,000{{nbsp}}YBP; 77 specimens dated 14,000–18,000{{nbsp}}YBP; 37 specimens dated 17,000–18,000{{nbsp}}YBP; 26 specimens dated 21,000–30,000{{nbsp}}YBP; 40 specimens dated 25,000–28,000{{nbsp}}YBP; and 6{{nbsp}}specimens dated 32,000–37,000{{nbsp}}YBP.<ref name=meachen2016/>{{rp|T1}} A specimen from Powder Mill Creek Cave, Missouri, was dated at 13,170{{nbsp}}YBP.<ref name=dundas1999/>

==Description==
[[File:C. dirus wiki.png|alt=|left|thumb|Size comparison with a human]]
The average dire wolf proportions were similar to those of two modern North American wolves: the [[Interior Alaskan wolf|Yukon wolf]] (''Canis lupus pambasileus'')<ref name=tedford325/><ref name=merriam1912/> and the [[Northwestern wolf]] (''Canis lupus occidentalis'').<ref name=tedford325/> The largest northern wolves today have a shoulder height of up to {{convert|38|in|cm|order=flip|abbr=on}} and a body length of {{convert|69|in|cm|order=flip|abbr=on}}.<ref name=mech1966/>{{rp|1}} Some dire wolf specimens from Rancho La{{nbsp}}Brea are smaller than this, and some are larger.<ref name=merriam1912/>
The dire wolf had smaller feet and a larger head than a northern wolf of the same body size. The skull length could reach {{convert|310|mm|in|abbr=on}} or longer, with a broader [[palate]], [[frontal region]], and [[zygomatic arches]] than the Yukon wolf. These dimensions make the skull very massive. Its [[sagittal crest]] was higher, with the [[external occipital protuberance|inion]] showing a significant backward projection, and with the rear ends of the [[nasal bones]] extending relatively far back into the skull. A connected skeleton of a dire wolf from Rancho La{{nbsp}}Brea is difficult to find because the tar allows the bones to disassemble in many directions. Parts of a [[vertebral column]] have been assembled, and it was found to be similar to that of the modern wolf, with the same number of vertebrae.<ref name=merriam1912/>

Geographic differences in dire wolves were not detected until 1984, when a study of skeletal remains showed differences in a few cranio-dental features and limb proportions between specimens from California and Mexico (''A.{{nbsp}}d.{{nbsp}}guildayi'') and those found from the east of the [[Continental Divide]] (''A.{{nbsp}}d.{{nbsp}}dirus''). A comparison of limb size shows that the rear limbs of ''A.{{nbsp}}d.{{nbsp}}guildayi'' were 8% shorter than the Yukon wolf due to a significantly shorter [[tibia]] and [[metatarsus]], and that the front limbs were also shorter due to their slightly shorter lower bones.<ref name=hartstone2015/><ref name=stock1948/> With its comparatively lighter and smaller limbs and massive head, ''A.{{nbsp}}d.{{nbsp}}guildayi'' was not as well adapted for running as timber wolves and coyotes.<ref name=stock1948/><ref name=merriam1912/> ''A.{{nbsp}}d.{{nbsp}}dirus'' possessed significantly longer limbs than ''A.{{nbsp}}d.{{nbsp}}guildayi''. The forelimbs were 14% longer than ''A.{{nbsp}}d.{{nbsp}}guildayi'' due to 10% longer [[Humeris|humeri]], 15% longer [[Radius (bone)|radii]], and 15% longer [[metacarpals]]. The rear limbs were 10% longer than ''A.{{nbsp}}d.{{nbsp}}guildayi'' due to 10% longer [[Femur|femora]] and tibiae, and 15% longer [[metatarsals]]. ''A.{{nbsp}}d.{{nbsp}}dirus'' is comparable to the Yukon wolf in limb length.<ref name=hartstone2015/> The largest ''A.{{nbsp}}d.{{nbsp}}dirus'' femur was found in Carroll Cave, Missouri, and measured {{convert|278|mm|in|abbr=on}}.<ref name=anyonge2005a/>

[[File:Canis lupus & Aenocyon dirus.jpg|thumb|upright=1.8|alt=Skeletons look identical|Gray wolf skeleton (left) and dire wolf skeleton]]

{| class="wikitable"
|+ ''Aenocyon dirus guildayi'' compared with the Yukon wolf by the mean length of limb bones in millimeters (inches)
! scope="col" | Limb variable
! scope="col" | ''A. d. guildayi''<ref name=stock1948/>
! scope="col" | Yukon wolf<ref name=stock1948/>
! scope="col" | ''A. d. dirus''<ref name=hartstone2015/>
|-
! scope="row" | Humerus (upper front leg)
| 218&nbsp;mm (8.6&nbsp;in)
| 237&nbsp;mm (9.3&nbsp;in)
| 240&nbsp;mm (9.4&nbsp;in)
|-
! scope="row" | Radius (lower front leg)
| 209&nbsp;mm (8.2&nbsp;in)
| 232&nbsp;mm (9.1&nbsp;in)
| 240&nbsp;mm (9.4&nbsp;in)
|-
! scope="row" | Metacarpal (front foot)
| 88&nbsp;mm (3.4&nbsp;in)
| 101&nbsp;mm (4.0&nbsp;in)
| 101&nbsp;mm (4.0&nbsp;in)
|-
! scope="row" | Femur (upper back leg)
| 242&nbsp;mm (9.5&nbsp;in)
| 251&nbsp;mm (9.9&nbsp;in)
| 266&nbsp;mm (10.5&nbsp;in)
|-
! scope="row" | Tibia (lower back leg)
| 232&nbsp;mm (9.1&nbsp;in)
| 258&nbsp;mm (10.2&nbsp;in)
| 255&nbsp;mm (10.0&nbsp;in)
|-
! scope="row" | Metatarsal (back foot)
| 93&nbsp;mm (3.7&nbsp;in)
| 109&nbsp;mm (4.3&nbsp;in)
| 107&nbsp;mm (4.2&nbsp;in)
|-
|}

''A.{{nbsp}}d.{{nbsp}}guildayi'' is estimated to have weighed on average {{convert|60|kg|lb|0|abbr=on}}, and ''A.{{nbsp}}d.{{nbsp}}dirus'' weighed on average {{convert|68|kg|lb|0|abbr=on}} with some specimens being larger,<ref name=anyonge2005a/> but these could not have exceeded {{convert|110|kg|lb|0|abbr=on}} due to skeletal limits.<ref name=sorkin2008/> In comparison, the average weight of the Yukon wolf is {{convert|43|kg|lb|abbr=on}} for males and {{convert|37|kg|lb|abbr=on}} for females. Individual weights for Yukon wolves can vary from {{convert|21|kg|lb|abbr=on}} to {{convert|55|kg|lb|abbr=on}},<ref name=yukon2017/> with one Yukon wolf weighing {{Convert|79.4|kg|lb|abbr=on}}.<ref name=mech1966/>{{rp|1}} These figures show the average dire wolf to be similar in size to the largest modern gray wolf.<ref name=anyonge2005a/>

The remains of a complete male ''A. dirus'' are sometimes easy to identify compared to other ''Canis'' specimens because the [[baculum]] (penis bone) of the dire wolf is very different from that of all other living [[Canidae|canids]].<ref name=dundas1999/><ref name=hartstone2015/> A 2024 study found the baculum of a male dire wolf to be proportionally longer than the baculum of modern canids, which may be indicative of stronger competition between males and unusual behaviors among canids, including [[non-monogamy|non-monogamous mating]].<ref>{{cite journal|last1=de Latorre |first1=D. V. |last2=Marshall |first2=C. R. |year=2024 |title=Evolutionary allometry of the canid baculum (Carnivora: Mammalia) |journal=Biological Journal of the Linnean Society |volume=144 |issue=4 |article-number=blae048 |doi=10.1093/biolinnean/blae048 |doi-access=free}}</ref>

==Adaptation==
[[File:Canis dirus.jpg|thumb|upright=0.75|alt=Painting of five dire wolves|Restoration of a pack in [[Rancho La Brea]] by [[Charles R. Knight]], 1922<ref>Rancho la Brea. Restoration by Chas. R. Knight. Mural for Amer. Museum Hall of Man. Coast Range in background, Old Baldy at left [http://geology.cwru.edu/~huwig/catalog/slides/748.B.17.jpg] {{Webarchive|url=https://web.archive.org/web/20130709044107/http://geology.cwru.edu/~huwig/catalog/slides/748.B.17.jpg|date=2013-07-09}}</ref>]]

Ecological factors such as habitat type, climate, prey specialization, and predatory competition have been shown to greatly influence gray wolf craniodental [[Phenotypic plasticity|plasticity]], which is an adaptation of the [[cranium]] and teeth due to the influences of the environment.<ref name=perri2016/><ref name=leonard2014/><ref name=flower2014/> Similarly, the dire wolf was a hypercarnivore, with a skull and dentition adapted for hunting large and struggling prey;<ref name=hodnett2009/><ref name=anyonge2005b/><ref name=wroe2005/> the shape of its skull and snout changed across time, and changes in the size of its body have been correlated with climate fluctuations.<ref name=okeefe2014/>

===Paleoecology===
The [[last glacial period]], commonly referred to as the "Ice Age", spanned 125,000<ref name=ipcc2007/>–14,500{{nbsp}}[[YBP]]<ref name=clark2009/> and was the most recent [[glacial period]] within the [[Quaternary glaciation|current ice age]], which occurred during the last years of the Pleistocene era.<ref name=ipcc2007/> The Ice Age reached its peak during the [[Last Glacial Maximum]], when [[ice sheet]]s began advancing from 33,000{{nbsp}}YBP and reached their maximum limits 26,500{{nbsp}}YBP. Deglaciation commenced in the Northern Hemisphere approximately 19,000{{nbsp}}YBP and in Antarctica approximately 14,500{{nbsp}}YBP, which is consistent with evidence that glacial meltwater was the primary source for an abrupt rise in sea level 14,500{{nbsp}}YBP.<ref name=clark2009/> Access into northern North America was blocked by the [[Wisconsin glaciation]]. The fossil evidence from the Americas points to the [[Quaternary extinction event|extinction]] mainly of large animals, termed [[Pleistocene megafauna]], near the end of the last glaciation.<ref name=elias2016/>

Coastal southern California from 60,000{{nbsp}}YBP to the end of the Last Glacial Maximum was cooler and with a more balanced supply of moisture than today. During the Last Glacial Maximum, the mean annual temperature decreased from {{convert|11|C|F}} down to {{convert|5|C|F}} degrees, and annual precipitation had decreased from {{convert|100|cm|inch|abbr=on}} down to {{convert|45|cm|inch|abbr=on}}.<ref name=coltrain2004/> This region was unaffected by the climatic effects of the Wisconsin glaciation and is thought to have been an Ice Age [[Refugium (population biology)|refugium]] for animals and cold-sensitive plants.<ref name=fox2007/><ref name=moratto1984/><ref name=johnson1977/> By 24,000{{nbsp}}YBP, the abundance of oak and chaparral decreased, but pines increased, creating open parklands similar to today's coastal [[montane]]/juniper woodlands. After 14,000{{nbsp}}YBP, the abundance of conifers decreased, and those of the modern coastal plant communities, including oak woodland, chaparral, and [[coastal sage scrub]], increased. The Santa Monica Plain lies north of the city of [[Santa Monica]] and extends along the southern base of the [[Santa Monica Mountains]], and 28,000–26,000{{nbsp}}YBP it was dominated by coastal sage scrub, with cypress and pines at higher elevations. The Santa Monica Mountains supported a chaparral community on its slopes and isolated coast redwood and dogwood in its protected canyons, along with river communities that included willow, red cedar, and sycamore. These plant communities suggest a winter rainfall similar to that of modern coastal southern California, but the presence of coast redwood now found {{convert|600|km|mi}} to the north indicates a cooler, moister, and less seasonal climate than today. This environment supported large herbivores that were prey for dire wolves and their competitors.<ref name=coltrain2004/>

===Prey===
[[File:Smilodon and Canis dirus.jpg|thumb|upright=1.1|alt=Sketch|Two dire wolves and a saber-toothed cat (''[[Smilodon]]'') with the carcass of a [[Columbian mammoth]] at the [[La Brea tar pits]] by [[Robert Bruce Horsfall|R.{{nbsp}}Bruce Horsfall]]<ref name=CWRU/>]]
A range of animal and plant specimens that became entrapped and were then preserved in tar pits have been removed and studied so that researchers can learn about the past. The Rancho La{{nbsp}}Brea tar pits located near Los Angeles in Southern California are a collection of pits of sticky asphalt deposits that differ in deposition time from 40,000 to 12,000{{nbsp}}YBP. Commencing 40,000{{nbsp}}YBP, trapped asphalt has been moved through fissures to the surface by methane pressure, forming seeps that can cover several square meters and be {{convert|9|–|11|m|abbr=on}} deep.<ref name=stock1992/> A large number of dire wolf fossils have been recovered from the La Brea tar pits.<ref name=wang148/> Over 200,000 specimens (mostly fragments) have been recovered from the tar pits,<ref name=anyonge2005a/> with the remains ranging from ''[[Smilodon]]'' to squirrels, invertebrates, and plants.<ref name=stock1992/>  The time period represented in the pits includes the Last Glacial Maximum when global temperatures were {{convert|8|C-change}} lower than today, the Pleistocene–Holocene transition ([[Bølling-Allerød]] interval), the [[Oldest Dryas]] cooling, the [[Younger Dryas]] cooling from 12,800 to 11,500{{nbsp}}YBP, and the American megafaunal extinction event 12,700{{nbsp}}YBP when 90 genera of mammals weighing over {{convert|44|kg|lb|abbr=on}} became extinct.<ref name=okeefe2009/><ref name=okeefe2014/>

[[Isotope analysis]] can be used to identify some chemical elements, allowing researchers to make inferences about the diet of the species found in the pits. Isotope analysis of bone [[collagen]] extracted from La{{nbsp}}Brea specimens provides evidence that the dire wolf, ''Smilodon'', and the [[American lion]] (''Panthera atrox'') competed for the same prey. Their prey probably included the extinct camel ''[[Camelops hesternus]]'', the extinct bison ''[[Bison antiquus]]'', the [[Capromeryx minor|"dwarf" pronghorn]] (''Capromeryx minor''), the equine ''[[Equus occidentalis]]'', and [[Harlan's ground sloth]] (''Paramylodon harlani'') native to North American grasslands. The [[Columbian mammoth]] (''Mammuthus columbi'') and the [[American mastodon]] (''Mammut americanum'') were rare at La{{nbsp}}Brea. The horses remained mixed feeders and the pronghorns mixed browsers, but at the Last Glacial Maximum and its associated shift in vegetation the camels and bison were forced to rely more heavily on conifers.<ref name=coltrain2004/>  A similar later isotope study of Rancho La Brea dire wolves in 2020 found a similar result, suggesting that they primarily fed on juvenile bison and camels, to a lesser extent on Harlan's ground sloth.<ref>{{Cite journal |last1=Fuller |first1=Benjamin T. |last2=Southon |first2=John R. |last3=Fahrni |first3=Simon M. |last4=Farrell |first4=Aisling B. |last5=Takeuchi |first5=Gary T. |last6=Nehlich |first6=Olaf |last7=Guiry |first7=Eric J. |last8=Richards |first8=Michael P. |last9=Lindsey |first9=Emily L. |last10=Harris |first10=John M. |date=January 2020 |title=Pleistocene paleoecology and feeding behavior of terrestrial vertebrates recorded in a pre-LGM asphaltic deposit at Rancho La Brea, California |url=https://linkinghub.elsevier.com/retrieve/pii/S0031018219305139 |journal=Palaeogeography, Palaeoclimatology, Palaeoecology |language=en |volume=537 |article-number=109383 |doi=10.1016/j.palaeo.2019.109383|bibcode=2020PPP...53709383F |url-access=subscription }}</ref> In Peccary Cave in the [[Ozarks|Ozark Mountains]] of Arkansas, the primary prey were likely [[flat-headed peccary]] (''Platygonus compressus'').<ref name=Hill2025>{{Cite journal |last1=Hill |first1=Matthew G. |last2=Widga |first2=Christopher C. |last3=Surovell |first3=Todd A. |last4=Wilson |first4=Kurt M. |last5=Allaun |first5=Sarah A. |last6=Litynski |first6=McKenna L. |last7=Titcomb |first7=Jason |date=2025-04-11 |title=An update on Aenocyon dirus in the interior of North America: new records, radiocarbon dates, ZooMS spectra, and isotopic data for an iconic late Pleistocene carnivore |journal=PeerJ |language=en |volume=13 |article-number=e19219 |doi=10.7717/peerj.19219 |pmid=40231072 |doi-access=free |issn=2167-8359|pmc=11995895 }}</ref> This indicates that the dire wolf was not a prey specialist, and at the close of the Late Pleistocene before its extinction it was hunting or scavenging the most available herbivores.<ref name="fox2007" /> A study based on specimens found in Cedral, San Luis Potosí found that the dire wolf primarily preyed on herbivores that consumed C4 plants and on mixed-diet herbivores.<ref name="PéRez-Crespo-2018">{{Cite journal |last1=PéRez-Crespo |first1=VíCtor AdriáN |last2=Arroyo-Cabrales |first2=JoaquíN |last3=Morales-Puente |first3=Pedro |last4=Cienfuegos-Alvarado |first4=Edith |last5=Otero |first5=Francisco J. |date=March 2018 |title=Diet and habitat of mesomammals and megamammals from Cedral, San Luis Potosí, México |url=https://www.cambridge.org/core/journals/geological-magazine/article/abs/diet-and-habitat-of-mesomammals-and-megamammals-from-cedral-san-luis-potosi-mexico/ABE31838193BF038107A916E2994B6DF |url-status=live |journal=[[Geological Magazine]] |language=en |volume=155 |issue=3 |pages=674–684 |bibcode=2018GeoM..155..674P |doi=10.1017/S0016756816000935 |issn=0016-7568 |archive-url=https://web.archive.org/web/20241127170526/https://www.cambridge.org/core/journals/geological-magazine/article/abs/diet-and-habitat-of-mesomammals-and-megamammals-from-cedral-san-luis-potosi-mexico/ABE31838193BF038107A916E2994B6DF |archive-date=27 November 2024 |access-date=22 October 2024 |via=Cambridge Core|url-access=subscription }}</ref>

Dire wolves likely scavenged on American mastodon and ground sloth carcasses.<ref name="PéRez-Crespo-2018" />

===Dentition and bite force===
[[File:Canis dirus skull.png|thumb|right|upright=0.75|alt=Three views of the skull from the side, above, and underneath|Skull of the dire wolf<ref>{{cite book|author=Merriam, J.C.|year=1911|title=The fauna of Rancho La Brea|publisher=University of California – Berkeley|volume=1|pages=[https://archive.org/details/faunaofrancholab02merr/page/224 224]–225|url=https://archive.org/details/faunaofrancholab02merr}}</ref>]]
When compared with the [[Canis#Dentition and biteforce|dentition of genus ''Canis'' members]], the dire wolf was considered the most evolutionary derived (advanced) wolf-like species in the Americas. The dire wolf could be identified separately from all other ''Canis'' species by its possession of "P2 with a posterior cusplet; P3 with two posterior cusplets; M1 with a mestascylid, entocristed, entoconulid, and a transverse crest extending from the metaconid to the hyperconular shelf; M2 with entocristed and entoconulid."<ref name=berta50/>

A study of the estimated bite force at the canine teeth of a large sample of living and fossil mammalian predators, when adjusted for the body mass, found that for [[placental]] mammals the bite force at the canines (in [[newton (unit)|newtons]]/kilogram of body weight) was greatest in the dire wolf (163), followed among the modern canids by the four hypercarnivores that often prey on animals larger than themselves: the [[African hunting dog]] (142), the gray wolf (136), the [[dhole]] (112), and the [[dingo]] (108). The bite force at the carnassials showed a similar trend to the canines. A predator's largest prey size is strongly influenced by its biomechanical limits. The morphology of the dire wolf was similar to that of its living relatives, and assuming that the dire wolf was a social hunter, then its high bite force relative to living canids suggests that it preyed on relatively large animals. The bite force rating of the bone-consuming [[spotted hyena]] (117) challenged the common assumption that high bite force in the canines and the carnassials was necessary to consume bone.<ref name=wroe2005/>

A study of the [[Morphometrics#Landmark-based geometric morphometrics|cranial measurements]] and jaw muscles of dire wolves found no significant differences with modern gray wolves in all but 4 of 15 measures. Upper dentition was the same except that the dire wolf had larger dimensions, and the P4 had a relatively larger, more massive blade that enhanced slicing ability at the carnassial. The jaw of the dire wolf had a relatively broader and more massive [[temporalis]] muscle, able to generate slightly more bite force than the gray wolf. Due to the jaw arrangement, the dire wolf had less temporalis leverage than the gray wolf at the lower carnassial (m1) and lower p4, but the functional significance of this is not known. The lower premolars were relatively slightly larger than those of the gray wolf,<ref name=anyonge2005b/> and the dire wolf m1 was much larger and had more shearing ability.<ref name=merriam1912/><ref name=kurten1980/><ref name=anyonge2005b/> The dire wolf canines had greater bending strength than those of living canids of equivalent size and were similar to those of hyenas and felids.<ref name=valkenburg1987/> All these differences indicate that the dire wolf was able to deliver stronger bites than the gray wolf, and with its flexible and more rounded canines was better adapted for struggling with its prey.<ref name=hodnett2009/><ref name=anyonge2005b/>

{| class="wikitable"
|+ ''Canis lupus'' and ''Aenocyon dirus'' compared by mean mandible tooth measurements (millimeters)
! scope="col" | Tooth variable
! scope="col" | ''lupus'' modern
North American<ref name=leonard2007/>
! scope="col" | ''lupus''<br /> La Brea<ref name=leonard2007/>
! scope="col" | ''lupus'' [[Beringian wolf|Beringia]]<ref name=leonard2007/>
! scope="col" | ''dirus dirus''<br /> [[Sangamonian]] era<ref name=kurten1984/><ref name=hodnett2009/>
(125,000–75,000 YBP)
! scope="col" | ''dirus dirus''<br /> [[Late Wisconsin]]<ref name=kurten1984/><ref name=hodnett2009/>
(50,000 YBP)
! scope="col" | ''dirus guildayi''<ref name=kurten1984/><ref name=hodnett2009/>
(40,000–13,000 YBP)
|-
! scope="row" | m1 length
| 28.2
| 28.9
| 29.6
| 36.1
| 35.2
| 33.3
|-
! scope="row" | m1 width
| 10.7
| 11.3
| 11.1
| 14.1
| 13.4
| 13.3
|-
! scope="row" | m1 [[trigonid]] length
| 19.6
| 21.9
| 20.9
| 24.5
| 24.0
| 24.4
|-
! scope="row" | p4 length
| 15.4
| 16.6
| 16.5
| 16.7
| 16.0
| 19.9
|-
! scope="row" | p4 width
| -
| -
| -
| 10.1
|  9.6
| 10.3
|-
! scope="row" | p2 length
| -
| -
| -
| 15.7
| 14.8
| 15.7
|-
! scope="row" | p2 width
| -
| -
| -
| 7.1
| 6.7
| 7.4
|-
|}

===Behavior===
At La Brea, predatory birds and mammals were attracted to dead or dying herbivores that had become mired, and then these predators became trapped themselves.<ref name=stock1992/><ref name=marcus1984/> Herbivore entrapment was estimated to have occurred once every fifty years,<ref name=marcus1984/> and for every instance of herbivore remains found in the pits there were an estimated ten carnivores.<ref name=stock1992/> ''A.{{nbsp}}d.{{nbsp}}guildayi'' is the most common carnivoran found at La{{nbsp}}Brea, followed by ''Smilodon''.<ref name=okeefe2009/><ref name=okeefe2014/> Remains of dire wolves outnumber remains of gray wolves in the tar pits by a ratio of five to one.<ref name=meachen2016/> During the Last Glacial Maximum, coastal California, with a climate slightly cooler and wetter than today, is thought to have been a refuge,<ref name=fox2007/> and a comparison of the frequency of dire wolves and other predator remains at La{{nbsp}}Brea to other parts of California and North America indicates significantly greater abundances; therefore, the higher dire wolf numbers in the La{{nbsp}}Brea region did not reflect the wider area.<ref name=mchorse2012/> Assuming that only a few of the carnivores that were feeding became trapped, it is likely that fairly sizeable groups of dire wolves fed together on these occasions.<ref name=valkenburgh2002/>
[[File:Aenocyon dirus Page.jpg|alt=Baculum bone is very long|left|thumb|Skeleton from the La Brea Tar Pits mounted in running pose. Note the [[baculum]] between the rear legs.]]
The difference between the male and female of a species apart from their sex organs is called [[sexual dimorphism]], and in this regard little variance exists among the canids. A study of dire wolf remains dated 15,360–14,310{{nbsp}}YBP and taken from one pit that focused on skull length, canine tooth size, and lower molar length showed little dimorphism, similar to that of the gray wolf, indicating that dire wolves lived in monogamous pairs.<ref name=valkenburgh2002/> Their large size and highly carnivorous dentition supports the proposal that the dire wolf was a predator that fed on large prey.<ref name=valkenburgh2002/><ref name=valkenburgh1993b/><ref name=valkenburgh1998/> To kill [[ungulates]] larger than themselves, the African wild dog, the dhole, and the gray wolf depend on their jaws as they cannot use their forelimbs to grapple with prey, and they work together as a pack consisting of an alpha pair and their offspring from the current and previous years. It can be assumed that dire wolves lived in packs of relatives that were led by an alpha pair.<ref name=valkenburgh2002/> Large and social carnivores would have been successful at defending carcasses of prey trapped in the tar pits from smaller solitary predators, and thus the most likely to become trapped themselves. The many ''A.{{nbsp}}d.{{nbsp}}guildayi'' and ''Smilodon'' remains found in the tar pits suggests that both were social predators.<ref name=mchorse2012/><ref name=carbone2009/>

All social terrestrial mammalian predators prey mostly on terrestrial herbivorous mammals with a body mass similar to the combined mass of the social group members attacking the prey animal.<ref name=sorkin2008/><ref name=earle1987/> The large size of the dire wolf provides an estimated prey size in the {{convert|300|to|600|kg|abbr=on}} range.<ref name=anyonge2005a/><ref name=valkenburgh1993b/><ref name=valkenburgh1998/> [[Isotope analysis#Reconstructing ancient diets|Stable isotope analysis]] of dire wolf bones provides evidence that they had a preference for consuming [[ruminants]] such as bison rather than other herbivores but moved to other prey when food became scarce, and occasionally scavenged on beached whales along the Pacific coast when available.<ref name=anyonge2005a/><ref name=anyonge2005b/><ref name=fox2003/> A pack of timber wolves can bring down a {{convert|500|kg|lb|abbr=on}} moose that is their preferred prey,<ref name=anyonge2005a/><ref name=mech1966/>{{rp|76}} and a pack of dire wolves bringing down a bison is conceivable.<ref name=anyonge2005a/> Although some studies have suggested that because of tooth breakage, the dire wolf must have gnawed bones and may have been a scavenger, its widespread occurrence and the more gracile limbs of the dire wolf indicate a predator. Like the gray wolf today, the dire wolf probably used its post-carnassial molars to gain access to marrow, but the dire wolf's larger size enabled it to crack larger bones.<ref name=anyonge2005b/>

====Tooth breakage====
[[File:Wolf dentition in the Ice Age.svg|thumb|alt=Nibbling by the incisors at the front of the mouth, next the canines for seizing, next the premolars for chewing, next the carnassials and molars for cutting and cracking|[[Dentition]] of an Ice Age wolf]]
Tooth breakage is related to a carnivore's behavior.<ref name=valkenburgh1993a/> A study of nine modern carnivores found that one in four adults had suffered tooth breakage and that half of these breakages were of the canine teeth. The most breakage occurred in the spotted hyena that consumes all of its prey including the bone; the least breakage occurred in the [[African wild dog]], and the gray wolf ranked in between these two.<ref name=valkenburgh1988/><ref name=valkenburgh1993a/> The eating of bone increases the risk of accidental fracture due to the relatively high, unpredictable stresses that it creates. The most commonly broken teeth are the canines, followed by the premolars, carnassial molars, and incisors. Canines are the teeth most likely to break because of their shape and function, which subjects them to bending stresses that are unpredictable in both direction and magnitude. The risk of tooth fracture is also higher when killing large prey.<ref name=valkenburgh1988/>

A study of the fossil remains of large carnivores from La{{nbsp}}Brea pits dated 36,000–10,000{{nbsp}}YBP shows tooth breakage rates of 5–17% for the dire wolf, coyote, American lion, and ''Smilodon'', compared to 0.5–2.7% for ten modern predators. These higher fracture rates were across all teeth, but the fracture rates for the canine teeth were the same as in modern carnivores.{{Clarify|date=April 2023}} The dire wolf broke its incisors more often than the modern gray wolf; thus, it has been proposed that the dire wolf used its incisors closer to the bone when feeding. Dire wolf fossils from Mexico and Peru show a similar pattern of breakage. A 1993 study proposed that the higher frequency of tooth breakage among Pleistocene carnivores than among living carnivores was not the result of hunting larger game, something that might be assumed from the larger size of the former. When there is low prey availability, the competition between carnivores increases, causing them to eat faster and thus consume more bone, leading to tooth breakage.<ref name=okeefe2014/><ref name=valkenburgh1993a/><ref name=valkenburgh2008b/> As their prey became extinct around 10,000 years ago, so did these Pleistocene carnivores, except for the coyote (which is an [[omnivore]]).<ref name=valkenburgh1993a/><ref name=valkenburgh2008b/>

A later La Brea pits study compared tooth breakage of dire wolves in two time periods. One pit contained fossil dire wolves dated 15,000{{nbsp}}YBP and another dated 13,000{{nbsp}}YBP. The results showed that the 15,000{{nbsp}}YBP dire wolves had three times more tooth breakage than the 13,000{{nbsp}}YBP dire wolves, whose breakage matched those of nine modern carnivores. The study concluded that between 15,000 and 14,000{{nbsp}}YBP prey availability was less or competition was higher for dire wolves and that by 13,000{{nbsp}}YBP, as the prey species moved towards extinction, predator competition had declined and therefore the frequency of tooth breakage in dire wolves had also declined.<ref name=valkenburgh2008b/><ref name=binder2002/>

Carnivores include both [[pack hunter]]s and solitary hunters. The solitary hunter depends on a powerful bite at the canine teeth to subdue their prey, and thus exhibits a strong [[mandibular symphysis]]. In contrast, a pack hunter, which delivers many shallower bites, has a comparably weaker mandibular symphysis. Thus, researchers can use the strength of the mandibular symphysis in fossil carnivore specimens to determine what kind of hunter it was{{snd}}a pack hunter or a solitary hunter{{snd}}and even how it consumed its prey. The mandibles of canids are buttressed behind the carnassial teeth to enable the animals to crack bones with their post-carnassial teeth (molars M2 and M3). A study found that the mandible buttress profile of the dire wolf was lower than that of the gray wolf and the red wolf, but very similar to the coyote and the African hunting dog. The dorsoventrally weak symphyseal region (in comparison to premolars P3 and P4) of the dire wolf indicates that it delivered shallow bites similar to its modern relatives and was therefore a pack hunter. This suggests that the dire wolf may have processed bone but was not as well adapted for it as was the gray wolf.<ref name=therrien2005/> The fact that the incidence of fracture for the dire wolf reduced in frequency in the Late Pleistocene to that of its modern relatives<ref name=valkenburgh1993a/><ref name=binder2002/> suggests that reduced competition had allowed the dire wolf to return to a feeding behavior involving a lower amount of bone consumption, a behavior for which it was best suited.<ref name=valkenburgh2008b/><ref name=therrien2005/>

The results of a study of [[dental microwear]] on tooth enamel for specimens of the carnivore species from La{{nbsp}}Brea pits, including dire wolves, suggest that these carnivores were not food-stressed just before their extinction. The evidence also indicated that the extent of carcass utilization (i.e., amount consumed relative to the maximum amount possible to consume, including breakup and consumption of bones) was less than among large carnivores today. These findings indicates that tooth breakage was related to hunting behavior and the size of prey.<ref name=desantis2015/>

===Climate impact===
Past studies proposed that changes in dire wolf body size correlated with climate fluctuations.<ref name=okeefe2014/><ref name=okeefe2008/> A later study compared dire wolf craniodental morphology from four La{{nbsp}}Brea pits, each representing four different time periods. The results are evidence of a change in dire wolf size, dental wear and breakage, skull shape, and snout shape across time. Dire wolf body size had decreased between the start of the Last Glacial Maximum and near its ending at the warm [[Allerød oscillation]]. Evidence of food stress (food scarcity leading to lower nutrient intake) is seen in smaller body size, skulls with a larger cranial base, and shorter snout (shape [[neoteny]] and size neoteny), and more tooth breakage and wear. Dire wolves dated 17,900{{nbsp}}YBP showed all of these features, which indicates food stress. Dire wolves dated 28,000{{nbsp}}YBP also showed to a degree many of these features but were the largest wolves studied, and it was proposed that these wolves were also suffering from food stress and that wolves earlier than this date were even bigger in size.<ref name=okeefe2014/> Nutrient stress is likely to lead to stronger bite forces to more fully consume carcasses and to crack bones,<ref name=okeefe2014/><ref name=tseng2010/> and with changes to skull shape to improve mechanical advantage. North American climate records reveal cyclic fluctuations during the glacial period that included rapid warming followed by gradual cooling, called [[Dansgaard–Oeschger event]]s. These cycles would have caused increased temperature and aridity, and at La{{nbsp}}Brea would have caused ecological stress and therefore food stress.<ref name=okeefe2014/> A similar trend was found with the gray wolf, which in the Santa Barbara basin was originally massive, robust, and possibly convergent evolution with the dire wolf, but was replaced by more gracile forms by the start of the Holocene.<ref name=nowak102/><ref name=goulet1993/><ref name=okeefe2014/>

:{| class="wikitable" style="text-align:center;"
|+ Dire wolf information based on skull measurements<ref name=okeefe2014/>
!scope="col"| Variable
!scope="col"| 28,000 [[YBP]]
!scope="col"| 26,100 YBP
!scope="col"| 17,900 YBP
!scope="col"| 13,800 YBP
|-
!scope="row"| Body size
| largest
| large
| smallest
| medium/small
|-
!scope="row"| Tooth breakage
| high
| low
| high
| low
|-
!scope="row"| Tooth wear
| high
| low
| high
| low
|-
!scope="row"| Snout shape
| shortening, largest cranial base
| average
| shortest, largest cranial base
| average
|-
!scope="row"| Tooth row shape
| robust
| –
| –
| gracile
|-
!scope="row"| [[Dansgaard–Oeschger event|DO]] event
| number&nbsp;3 or 4
| none
| imprecise data
| imprecise data
|}

===Competitors===
[[File:Annual report of the American Museum of Natural History for the year (1913) (18246516009).jpg|thumb|upright=1.1|Mounted skeletons of ''Smilodon'' and dire wolf near ground sloth bones]]
Just before the appearance of the dire wolf, North America was invaded by the ''Canis'' subgenus ''[[Xenocyon]]'' (ancestor of the Asian dhole and the African hunting dog) that was as large as the dire wolf and more hypercarnivorous. The fossil record shows them as rare, and it is assumed that they could not compete with the newly derived dire wolf.<ref name=wang60/> Stable isotope analysis provides evidence that the dire wolf, ''[[Smilodon fatalis]]'', and the [[American lion]] competed for the same prey.<ref name=coltrain2004/><ref name=desantis2015/> Other large carnivores included the extinct North American giant [[Arctodus|short-faced bear]] (''Arctodus simus''), the modern [[cougar]] (''Puma concolor''), the [[Pleistocene coyote]] (''Canis latrans''), and the [[Pleistocene wolf|Pleistocene gray wolf]] that was more massive and robust than today. These predators may have competed with humans who hunted for similar prey.<ref name=desantis2015/>

Specimens that have been identified by morphology as [[Beringian wolf|Beringian wolves]] (''C.{{nbsp}}lupus'') and radiocarbon dated 25,800–14,300 YBP have been found in the [[Natural Trap Cave]] at the base of the [[Bighorn Mountains]] in [[Wyoming]], in the western United States. The location is directly south of what would at that time have been a division between the [[Laurentide Ice Sheet]] and the [[Cordilleran Ice Sheet]]. A temporary channel between the glaciers may have existed that allowed these large, Alaskan direct competitors of the dire wolf, which were also adapted for preying on megafauna, to come south of the ice sheets. Dire wolf remains are absent north of the 42°N{{nbsp}}latitude in North America, therefore, this region would have been available for Beringian wolves to expand south along the glacier line. How widely they were then distributed is not known. These also became extinct at the end of the Late Pleistocene, as did the dire wolf.<ref name=meachen2016/>

After arriving in eastern [[Eurasia]], the dire wolf would have likely faced competition from the area's most dominant, widespread predator, the eastern subspecies of [[cave hyena]] (''Crocuta crocuta ultima''). Competition with this species may have kept Eurasian dire wolf populations very low, leading to the paucity of dire wolf fossil remains in this otherwise well-studied fossil fauna.<ref name=Lu2020/>

==Range==
[[File:Canis dirus findings USA.png|thumb|upright=1.35|US states where dire wolf remains have been found are shaded gray]]
Dire wolf remains have been found across a broad range of habitats including the plains, grasslands, and some forested mountain areas of North America, the arid savannah of South America, and possibly the steppes of eastern Asia. The sites range in elevation from sea level to {{convert|2255|m|-1|abbr=on}}.<ref name=dundas1999/> The location of these fossil remains suggests that dire wolves lived predominantly in the open lowlands along with their prey, the large herbivores.<ref name=nowak116/> Dire wolf remains are not often found at high latitudes in North America,<ref name=dundas1999/> with the northernmost record in southern Canada.<ref>{{Cite journal|last1=Reynolds |first1=A. R. |last2=Lowi-Merri |first2=T. M. |last3=Brannick |first3=A. L. |last4=Seymour |first4=K. L. |last5=Churcher |first5=C. S. |last6=Evans |first6=D. C. |year=2023 |title=Dire wolf (''Canis dirus'') from the late Pleistocene of southern Canada (Medicine Hat, Alberta) |journal=Journal of Quaternary Science |volume=38 |issue=6 |pages=938–946 |doi=10.1002/jqs.3516 |s2cid=257905013 |doi-access=free |bibcode=2023JQS....38..938R }}</ref>

In the United States, dire wolf fossils have been reported in Arizona, California, Florida, Idaho, Indiana, Kansas, Kentucky, Missouri, Nebraska, New Mexico, Oregon, Pennsylvania, South Carolina, South Dakota, Texas, Utah, Virginia, West Virginia, Wyoming,<ref name=dundas1999/> and Nevada.<ref name=scott2016/> The identity of fossils reported farther north than California is not confirmed.<ref name=meachen2016/> There have been five reports of unconfirmed dire wolf fossils north of 42°N{{nbsp}}latitude, at [[Fossil Lake (Oregon)|Fossil Lake, Oregon]] (125,000–10,000{{nbsp}}YBP), [[American Falls Reservoir|American Falls Reservoir, Idaho]] (125,000–75,000{{nbsp}}YBP), Salamander Cave, South Dakota (250,000{{nbsp}}YBP), and four closely grouped sites in northern Nebraska (250,000{{nbsp}}YBP).<ref name=meachen2016/> This suggests a range restriction on dire wolves due to temperature, prey, or habitat.<ref name=meachen2016/> The major fossil-producing sites for ''A.{{nbsp}}d.{{nbsp}}dirus'' are located east of the [[Rocky Mountains]] and include Friesenhahn Cave, near San Antonio, Texas; Carroll Cave, near Richland, Missouri; and [[Reddick, Florida]].<ref name=anyonge2005a/>

[[File:Paleontological landscape painting, White Sands National Park, United States.jpg|thumb|left|alt=Painting of animals around a lake|Environment of what is now [[White Sands National Park]], with dire wolves feeding on the left]]
Localities in Mexico where dire wolf remains have been collected include El{{nbsp}}Cedazo in [[Aguascalientes]]; [[Comondú Municipality]] in [[Baja California Sur]]; El{{nbsp}}Cedral in [[San Luis Potosí]]; El{{nbsp}}Tajo Quarry near [[Tequixquiac]], [[State of Mexico]]; Valsequillo in [[Puebla]]; [[Lago de Chapala]] in [[Jalisco]]; [[Loltun Cave]] in [[Yucatán]]; Potrecito in [[Sinaloa]]; San Josecito Cave near [[Aramberri]] in [[Nuevo León]]; and Térapa in [[Sonora]]. The specimens from Térapa were confirmed as ''A.{{nbsp}}d.{{nbsp}}guildayi''.<ref name=hodnett2009/> The finds at San Josecito Cave and El{{nbsp}}Cedazo have the greatest number of individuals from a single locality.

In South America, dire wolves have been dated younger than 17,000 YBP and have been reported from six localities: Muaco in the western [[Falcón]] state of [[Venezuela]], [[Talara Province]] in [[Peru]], [[Monagas]] state in eastern [[Venezuela]], the [[Tarija Department]] in [[Bolivia]], [[Atacama Desert]] of [[Chile]], and [[Ecuador]].{{sfn|Tedford|Wang|Taylor|2009|p=146}}<ref>{{cite journal |first1=Francisco J. |last1=Caro |first2=Rafael |last2=Labarca |first3=Francisco J. |last3=Prevosti |first4=Natalia |last4=Villavicencio |first5=Gabriela M. |last5=Jarpa |first6=Katherine A. |last6=Herrera |first7=Jacqueline |last7=Correa-Lau |first8=Claudio |last8=Latorre |first9=Calogero M. |last9=Santoro |year=2023 |title=First record of cf. ''Aenocyon dirus'' (Leidy, 1858) (Carnivora, Canidae), from the Upper Pleistocene of the Atacama Desert, northern Chile |journal=Journal of Vertebrate Paleontology |volume=42 |issue=4 |article-number=e2190785 |doi=10.1080/02724634.2023.2190785|s2cid=258757704 }}</ref><ref name=dundas1999/><ref name=RR2022>{{Cite journal|url=https://bioone.org/journals/ameghiniana/volume-59/issue-1/AMGH.16.09.2021.3448/Canids-Caninae-from-the-Past-of-Venezuela/10.5710/AMGH.16.09.2021.3448.short|doi = 10.5710/AMGH.16.09.2021.3448|title = Canids (Caninae) from the Past of Venezuela|year = 2022|last1 = Ruiz-Ramoni|first1 = Damián|last2 = Wang|first2 = Xiaoming|last3 = Rincón|first3 = Ascanio D.|journal = Ameghiniana|volume = 59| page=448 | bibcode=2022Amegh..59..448R |s2cid = 240576546|url-access = subscription}}</ref> If the dire wolf originated in North America, the species likely dispersed into South America via the Andean corridor,<ref name=dundas1999/><ref name=berta119/> a proposed pathway for temperate mammals to migrate from Central to South America because of the favorable cool, dry, and open habitats that characterized the region at times. This most likely happened during a glacial period because the pathway then consisted of open, arid regions and savanna but during inter-glacial periods consisted of tropical rain forest.<ref name=dundas1999/><ref name=webb1991/>

In 2020, a fossil mandible (IVPP V25381) later analyzed as a dire wolf's was found in the vicinity of [[Harbin]], northeastern China. The fossil was taxonomically described and dated 40,000 YBP. This discovery challenges previous theories that the cold temperatures and ice sheets at northern latitudes in North America would be a barrier for dire wolves, which was based on no dire wolf fossils being found above [[42nd parallel north|42° latitude]] in North America. It is proposed that the dire wolf followed migrating prey from mid-latitude North America across [[Beringia]] into Eurasia.<ref name=Lu2020/> However, the 2022 study argued that the morphology and size of the specimen is inconclusive for its taxonomic determination as a dire wolf.<ref name=RR2022/>

==Extinction==
[[File:The American Museum journal (c1900-(1918)) (17974394119).jpg|thumb|alt=Line art of a dire wolf|Restoration of a dire wolf by an asphalt pool, by E. S. Christman, 1913]]
During the [[Quaternary extinction event]] around 12,700{{nbsp}}YBP, 90{{nbsp}}genera of mammals weighing over {{convert|44|kg}} became extinct.<ref name=okeefe2009/><ref name=okeefe2014/> The extinction of the large carnivores and scavengers is thought to have been caused by the extinction of the megaherbivore prey upon which they depended.<ref name=graham1987/><ref name=barnosky1989/><ref name=dundas1999/><ref name=valkenburgh1993a/> The cause of the extinction of the megafauna themselves is debated<ref name=desantis2015/> but has been attributed to the impact of [[climate change (general concept)|climatic change]], [[competition (biology)|competition]] with other species including [[overexploitation]] by newly arrived human hunters, or a combination of both.<ref name=desantis2015/><ref name=brannick2015/> One study proposes that several extinction models should be investigated because so little is known about the biogeography of the dire wolf and its potential competitors and prey, nor how all these species interacted and responded to the environmental changes that occurred at the time of extinction.<ref name=dundas1999/>

Ancient DNA and radiocarbon data indicate that local genetic populations were replaced by others within the same species or by others within the same genus.<ref name=cooper2015/> Both the dire wolf and the [[Beringian wolf]] went extinct in North America, leaving only the less carnivorous and more gracile form of the wolf to thrive,<ref name=leonard2007/> which may have outcompeted the dire wolf.<ref name=anderson1984/> One study proposes an early origin of the dire wolf lineage in the Americas which led to its reproductive isolation, such that when coyotes, dholes, gray wolves, and ''Xenocyon'' expanded into North America from Eurasia in the Late Pleistocene there could be no admixture with the dire wolf. Gray wolves and coyotes may have survived due to their ability to hybridize with other canids – such as the domestic dog – to acquire traits that resist diseases brought by taxa arriving from Eurasia. Reproductive isolation may have prevented the dire wolf from acquiring these traits.<ref name=Perri2021/> A 2023 study documented a high degree of [[subchondral defects]] in joint surfaces of dire wolf and ''Smilodon'' specimens from the La Brea Tar pits that resembled [[osteochondrosis dissecans]]. As modern dogs with this disease are [[inbred]], the researchers suggested this would have been the case for the prehistoric species as well as they approached extinction, but cautioned that more research was needed to determine if this was also the case in specimens from other parts of the Americas.<ref name="Subchondral defects">{{cite journal |last1=Schmökel |first1=Hugo |last2=Farrell |first2=Aisling |last3=Balisi |first3=Mairin F. |title=Subchondral defects resembling osteochondrosis dissecans in joint surfaces of the extinct saber-toothed cat ''Smilodon fatalis'' and dire wolf ''Aenocyon dirus'' |journal=PLOS ONE |date=2023 |volume=18 |issue=7 |article-number=e0287656 |doi=10.1371/journal.pone.0287656|pmid=37436967 |pmc=10337945 |doi-access=free |bibcode=2023PLoSO..1887656S }}</ref>

In 2019 the youngest known specimen of the 35 dire wolf fossils collected from Rancho La Brea, California was dated at 11,413 ± 754 [[Radiocarbon calibration|calibrated]] years [[before present]] (YBP),<ref>{{cite thesis|author=Finkelman, L.|year=2019|title=Anthropogenic and Non-anthropogenic Contributions to End-Pleistocene Megafaunal Extinctions in the American West|publisher=University of Oregon|degree=MSc|pages=45–46}}</ref> while in 2022 the bone collagen of a dire wolf also known from Rancho La Brea, California was dated at 11,581 ± 3,768 calibrated YBP.<ref>{{cite journal|author1=DeSantis, L.R.G.|author2=Feranec, R.S.|author3=Southon, J.|author4=Cerling, T.E.|author5=Harris, J.|author6=Binder, W.J.|author7=Cohen, J.E.|author8=Farrell, A.B.|author9=Lindsey, E.L.|author10=Meachen, J.|author11=O'Keefe, F.R.|author12=Takeuchi, G.T.|year=2022|title=On the relationship between collagen- and carbonate-derived carbon isotopes with implications for the inference of carnivore dietary behavior|journal=Frontiers in Ecology and Evolution|volume=20|article-number=1031383|doi=10.3389/fevo.2022.1031383|doi-access=free |bibcode=2022FrEEv..1031383D |hdl=1803/17954|hdl-access=free}}</ref> The youngest uncalibrated geological ages assigned to dire wolf remains are dated at 9,440{{nbsp}}YBP at Brynjulfson Cave, [[Boone County, Missouri]],<ref name=kurten1980/><ref name=anderson1984/> 9,860{{nbsp}}YBP at Rancho La Brea, California, and 10,690{{nbsp}}YBP at [[La Mirada, California]].<ref name=anderson1984/> Some remains have been radiocarbon dated (uncalibrated) to 8,200{{nbsp}}YBP from [[Whitewater Draw]] in [[Arizona]],<ref name=brannick2015/><ref name=hester1960/> though one author has stated that radiocarbon dating of bone carbonate is unreliable.<ref name=dundas1999/> In South America, the most recent remains at [[Talara]], Peru date to 9,030 ± 240 YBP (also uncalibrated), while the most recent remains of "''C. nehringi''" from [[Luján, Buenos Aires|Luján]], Argentina are older than the most recent [[stratigraphical]] section of the site, dated to 10–11,000 YBP.<ref name = "Prevosti1">{{cite journal|author1=Prevosti, F.J.|author2=Tonni, E.P.|author3=Bidegain, J.C.|year=2009|title=Stratigraphic range of the large canids (Carnivora, Canidae) in South America, and its relevance to quaternary biostratigraphy|journal=Quaternary International|volume=210|issue=1–2|pages=76–81|doi=10.1016/j.quaint.2009.06.034|bibcode=2009QuInt.210...76P |hdl=11336/103725 |hdl-access=free}}</ref>

=== Revival efforts ===
====Dire Wolf Project====
[[File:Asdirewolf.jpg|thumb|A 10-month-old American Alsatian, one of the dog breeds used for the Dire Wolf Project]]
There have been attempts to recreate the dire wolf or its phenotype. The first, the Dire Wolf Project, is a program initiated in 1988 by Lois Schwarz of the American Alsatian Breeders Association, aiming to selectively breed dogs to present a dire wolf-like appearance and sell them to private owners.<ref name=direwolfproject>{{Cite web |title=Find out about the Dire Wolf Project |url=https://direwolfproject.com/about-us/ |access-date=2025-04-07 |website=direwolfproject.com |language=en}}</ref><ref name=Edidin>{{cite web|author=Edidin, R.|date=2013-03-26|title=Your Dreams of Owning a Dire Wolf Can Finally Come True (Sort Of)|website=Wired.com|url=https://www.wired.com/2013/03/dire-wolf-pet-dog/|access-date=2025-04-26}}</ref> The dogs were originally produced by crossing [[German shepherd]]s and [[Alaskan malamute]]s, with [[English mastiff]]s and [[great Pyrenees]] added for mass and proportions, [[Akita (dog breed)|Akita]]s for shorter ears and [[Irish wolfhound]]s for height and length.<ref>{{cite news|author=Brulliard, K.|date=2017-07-31|title=Dire wolves were real. Now someone is trying to resurrect them.|newspaper=The Washington Post|url=https://www.washingtonpost.com/news/animalia/wp/2017/07/31/dire-wolves-were-real-now-someone-is-trying-to-resurrect-them/|access-date=2025-04-26}}</ref><ref>{{Cite web |title=Our History |url=https://direwolfproject.com/about-us/our-history/ |access-date=2025-04-26 |website=direwolfproject.com |language=en}}</ref> As Schwarz herself acknowledges, the project is not based on the [[scientific method]], with the dogs being selected purely on "wishful and fantasy-oriented" aesthetic and practical grounds "matched more to the needs of prospective owners than prehistoric fact".<ref name=direwolfproject/><ref name=Edidin/>

====Colossal Biosciences====
{{Main|Colossal Biosciences dire wolf project}}
In April 2025, it was announced that [[Colossal Biosciences]] used [[cloning]] and [[Genetic engineering|gene-editing]] to birth [[Romulus, Remus, and Khaleesi|three genetically modified wolf pups]], six-month-old males Romulus and Remus and two-month-old female Khaleesi. In-house scientists made 20 edits to 14 key genes in [[gray wolf]] [[Endothelial progenitor cell|EPC cells]] to match those genes from the dire wolf in order to recreate distinctive dire wolf traits. Colossal stated that these minor genetic modifications effectively revive dire wolves as a species. No ancient dire wolf DNA was actually spliced into the gray wolf's genome.<ref name=Klinger>{{Cite magazine|url=https://time.com/7274542/colossal-dire-wolf/|author=Jeffrey Klinger|title=The Return of the Dire Wolf|date=April 7, 2025|magazine=Time|access-date=April 7, 2025|archive-date=April 7, 2025|archive-url=https://web.archive.org/web/20250407144101/https://time.com/7274542/colossal-dire-wolf/|url-status=live}}</ref><ref name=Max>{{Cite magazine|url=https://www.newyorker.com/magazine/2025/04/14/the-dire-wolf-is-back|author=D. T. Max|title=The Dire Wolf is Back|date=April 7, 2025|magazine=The New Yorker|access-date=April 7, 2025|archive-date=April 7, 2025|archive-url=https://web.archive.org/web/20250407131025/https://www.newyorker.com/magazine/2025/04/14/the-dire-wolf-is-back|url-status=live}}</ref><ref name=Kluger>{{cite magazine|url=https://time.com/7275439/science-behind-dire-wolf-return/|author=Jeffrey Kluger|date=April 7, 2025|title=The Science Behind the Return of the Dire Wolf|magazine=Time}}</ref>

Independent experts disagreed with the Colossal Biosciences' claim that these animals are revived dire wolves, asserting that they are "not a dire wolf under any definition of a species ever".<ref>{{cite web|author=Gill, V.|date=2025-04-08|title=Experts dispute claim dire wolf brought back from extinction|website=BBC News|url=https://www.bbc.com/news/articles/c4g9ejy3gdvo|access-date=2025-04-08|archive-date=2025-04-08|archive-url=https://web.archive.org/web/20250408134503/https://www.bbc.com/news/articles/c4g9ejy3gdvo|url-status=live}}</ref><ref>{{cite web|author=Cassella, C.|title=Did Dire Wolves Just Come Back From Extinction? Here's The Truth.|date=2025-04-08|website=ScienceAlert|url=https://www.sciencealert.com/did-dire-wolves-just-come-back-from-extinction-heres-the-truth|access-date=2025-04-08|archive-date=2025-04-08|archive-url=https://web.archive.org/web/20250408092958/https://www.sciencealert.com/did-dire-wolves-just-come-back-from-extinction-heres-the-truth|url-status=live}}</ref> The [[IUCN Species Survival Commission]] Canid Specialist Group officially declared that the three animals are neither dire wolves nor proxies of the dire wolves based on the IUCN SSC guiding principles on creating proxies of extinct species for conservation benefit. They commented that creating phenotypic proxies does not change the conservation status of an extinct species and may instead threaten the extant species such as gray wolves, and therefore concluded that the Colossal Biosciences' project "does not contribute to conservation."<ref>{{cite journal|author1=Kitchener, A.|author2=Sacks, B.|author3=Sillero, C.|author4=Chavez, D.|author5=Machado, F.|author6=Werhahn, G.|author7=Senn, H.|author8=Marino, J.|author9=Cairns, K.|author10=Hennelly, L.|author11=Hoffmann, M.|author12=Viranta, S.|date=2025-04-18|title=Conservation perspectives on gene editing in wild canids: Commentary on the announced re-creation of a genetic proxy of an extinct dire wolf by Colossal|journal=IUCN Species Survival Commission Canid Specialist Group|url=https://www.canids.org/resources/CSG%20gene%20editing%20in%20wild%20canids.pdf}}</ref> Colossal Biosciences released a clarifying document ''Alignment of Colossal's Dire Wolf De-Extinction Project with IUCN SSC Guiding Principles'' in response.<ref>{{Cite web|url=https://colossal.com/wp-content/themes/colossal/IUCN_SSC_Alignment.pdf|title=Alignment of Colossal's Dire Wolf De-Extinction Project with IUCN SSC Guiding Principles|website=colossal.com|access-date=2025-05-16}}</ref> 

In May 2025, the company's chief scientist [[Beth Shapiro]] stated that the three animals are "grey wolves with 20 edits" as purportedly stated by the company "from the very beginning", acknowledging that it is impossible to bring back an extinct organism, or at least an organism "identical to a species that used to be alive". She stated that the term "dire wolves" applied to the pups are a [[colloquialism]]. This was called a "major departure from what Colossal had said previously".<ref>{{cite web|author=Le Page, M.|date=2025-05-22|title=Colossal scientist now admits they haven't really made dire wolves|url=https://www.newscientist.com/article/2481409-colossal-scientist-now-admits-they-havent-really-made-dire-wolves/|access-date=2025-05-22|website=New Scientist}}</ref>

==See also==
{{Portal|Paleontology}}
* [[List of North American animals extinct in the Holocene]]
* [[List of South American animals extinct in the Holocene]]

==Notes==
{{Notelist| group = note}}

==References==
{{Reflist|colwidth=30em|refs=

<ref name=allen1876>{{cite journal |title=Description of some remains of an extinct species of wolf and an extinct species of deer from the lead region of the upper Mississippi |journal=[[American Journal of Science]] |issue=61 |pages=47–51 |year=1876 |last1=Allen |first1=J. A. |url=https://www.biodiversitylibrary.org/item/113474#page/56/mode/1up |doi=10.2475/ajs.s3-11.61.47 |volume=s3-11 |bibcode=1876AmJS...11...47A |hdl=2027/hvd.32044107326068 |s2cid=88320413 |hdl-access=free |archive-date=2021-01-28 |access-date=2018-01-14 |archive-url=https://web.archive.org/web/20210128083835/https://www.biodiversitylibrary.org/item/113474#page/56/mode/1up |url-status=live }}</ref>

<ref name=Alvares2019>{{cite web|first1=Francisco|last1=Alvares|first2=Wieslaw|last2=Bogdanowicz|first3=Liz A.D.|last3=Campbell|first4=Rachel|last4=Godinho|first5=Jennifer|last5=Hatlauf|first6=Yadvendradev V.|last6=Jhala|first7=Andrew C.|last7=Kitchener|first8=Klaus-Peter|last8=Koepfli|first9=Miha|last9=Krofel|first10=Patricia D.|last10=Moehlman|first11=Helen|last11=Senn|first12=Claudio|last12=Sillero-Zubiri|first13=Suvi|last13=Viranta|first14=Geraldine|last14=Werhahn|year=2019|website=IUCN/SSC Canid Specialist Group|url=https://www.canids.org/CBC/Old_World_Canis_Taxonomy_Workshop.pdf|title=Old World ''Canis'' spp. with taxonomic ambiguity: Workshop conclusions and recommendations. CIBIO. Vairão, Portugal, 28th–30th May 2019|access-date=6 March 2020|archive-date=12 February 2020|archive-url=https://web.archive.org/web/20200212111856/https://www.canids.org/CBC/Old_World_Canis_Taxonomy_Workshop.pdf|url-status=live}}</ref>

<ref name=anderson1984>{{cite book |last1=Anderson |first1=Elaine |title=Quaternary Extinctions: A Prehistoric Revolution |publisher=[[University of Arizona Press]] |location=Tucson |editor1=Paul S. Martin |editor2=Richard G. Klein |year=1984 |chapter=Chapter 2: Who's who in the Pleistocene |page=55 |chapter-url=https://books.google.com/books?id=qIDC7ybvHQEC&pg=PA55 |isbn=978-0-8165-1100-6}}</ref>

<ref name=anyonge2005a>{{cite journal |doi=10.1671/0272-4634(2006)26[209:NBMEFC]2.0.CO;2 |year=2006 |volume=26 |pages=209–212 |title=New body mass estimates for ''Canis dirus'', the extinct Pleistocene dire wolf |journal=Journal of Vertebrate Paleontology |last1=Anyonge |first1=William |last2=Roman |first2=Chris|s2cid=83702167 }}</ref>

<ref name=anyonge2005b>{{cite journal |doi=10.1111/j.1469-7998.2006.00043.x |title=Craniofacial morphology and feeding behavior in ''Canis dirus'', the extinct Pleistocene dire wolf |journal=[[Journal of Zoology]] |volume=269 |issue=3 |pages=309–316 |year=2006 |last1=Anyonge |first1=W. |last2=Baker |first2=A.}}</ref>

<ref name=barnosky1989>{{cite book |last1=Barnosky |first1=A. D. |chapter=The Late Pleistocene extinction event as a paradigm for widespread mammal extinction |title=Mass Extinctions: Processes and Evidence |editor1-last=Donovan |editor1-first=Stephen K. |publisher=[[Columbia University Press]], New York |year=1989 |isbn=978-0-231-07091-1 |pages=235–255}}</ref>

<ref name=berta50>{{Harvnb|Berta|1988|pp=50}}</ref>

<ref name=berta113>{{Harvnb|Berta|1988|pp=113}}</ref>

<ref name=berta119>{{Harvnb|Berta|1988|pp=119}}</ref>

<ref name=binder2002>{{cite journal |doi=10.1671/0272-4634(2002)022[0423:TVITFA]2.0.CO;2 |year=2002 |volume=22 |issue=2 |pages=423–428 |title=Temporal variation in tooth fracture among Rancho La Brea dire wolves |journal=Journal of Vertebrate Paleontology |last1=Binder |first1=Wendy J. |last2=Thompson |first2=Elicia N. |last3=Van Valkenburgh |first3=Blaire|s2cid=85799312 }}</ref>

<ref name=brannick2015>{{cite journal |last1=Brannick |first1=Alexandria L. |last2=Meachen |first2=Julie A. |last3=O'Keefe |first3=F. Robin |title=Microevolution of Jaw Shape in the Dire Wolf, ''Canis dirus'', at Rancho La Brea |publisher=Natural History Museum of Los Angeles County |series=Science Series 42 |journal=Contributions in Science |issue=A Special Volume Entitled la Brea and Beyond: The Paleontology of Asphalt-Preserved Biotas in Commemoration of the 100th Anniversary of the Natural History Museum of Los Angeles County's Excavations at Rancho la Brea |editor=John M. Harris |date=September 15, 2015 |pages=23–32}}</ref>

<ref name=carbone2009>{{cite journal |doi=10.1098/rsbl.2008.0526 |pmid=18957359 |pmc=2657756 |title=Parallels between playbacks and Pleistocene tar seeps suggest sociality in an extinct sabretooth cat, ''Smilodon'' |journal=Biology Letters |volume=5 |issue=1 |pages=81–5 |year=2009 |last1=Carbone |first1=C. |last2=Maddox |first2=T. |last3=Funston |first3=P. J. |last4=Mills |first4=M. G. L. |last5=Grether |first5=G. F. |last6=Van Valkenburgh |first6=B.}}</ref>

<ref name=clark2009>{{cite journal |doi=10.1126/science.1172873 |pmid=19661421 |title=The Last Glacial Maximum |journal=Science |volume=325 |issue=594 1|pages=710–4 |year=2009 |last1=Clark |first1=P. U. |last2=Dyke |first2=A. S. |last3=Shakun |first3=J. D. |last4=Carlson |first4=A. E. |last5=Clark |first5=J. |last6=Wohlfarth |first6=B. |last7=Mitrovica |first7=J. X. |last8=Hostetler |first8=S. W. |last9=McCabe |first9=A. M.|author-link6=Barbara Wohlfarth |bibcode=2009Sci...325..710C|s2cid=1324559 }}</ref>

<ref name=coltrain2004>{{cite journal |doi=10.1016/j.palaeo.2003.12.008 |title=Rancho La Brea stable isotope biogeochemistry and its implications for the palaeoecology of late Pleistocene, coastal southern California |journal=Palaeogeography, Palaeoclimatology, Palaeoecology |volume=205 |issue=3–4 |pages=199–219 |year=2004 |last1=Coltrain |first1=Joan Brenner |last2=Harris |first2=John M. |last3=Cerling |first3=Thure E. |last4=Ehleringer |first4=James R. |last5=Dearing |first5=Maria-Denise |last6=Ward |first6=Joy |last7=Allen |first7=Julie |bibcode=2004PPP...205..199C}}</ref>

<ref name=cooper2015>{{cite journal |author=Cooper, A. |year=2015 |title=Abrupt warming events drove Late Pleistocene Holarctic megafaunal turnover |journal=[[Science (journal)|Science]] |volume=349 |issue=6248 |pages=602–6 |doi=10.1126/science.aac4315 |pmid=26250679|bibcode=2015Sci...349..602C |s2cid=31686497 |doi-access=free }}</ref>

<ref name=CWRU>{{cite web |url=http://geology.cwru.edu/~huwig/catalog/slides/748.B.15.jpg |title=Rancho la Brea Tar Pool. Restoration by Bruce Horsfall for W.B. Scott |author=College of Arts and Sciences |website=Case Western Reserve University |year=2016 |access-date=24 December 2016 |archive-date=26 February 2007 |archive-url=https://web.archive.org/web/20070226222843/http://geology.cwru.edu/~huwig/catalog/slides/748.B.15.jpg |url-status=live }}</ref>

<ref name=Lu2020>{{cite journal|last1=Lu|first1=Dan|last2=Yang|first2=Yangheshan|last3=Lia|first3=Qiang|last4=Nia|first4=Xijun|date=1 October 2020|title=A late Pleistocene fossil from Northeastern China is the first record of the dire wolf (Carnivora: Canis dirus) in Eurasia|journal=Quaternary International|volume=591|pages=87–92|doi=10.1016/j.quaint.2020.09.054|bibcode=2021QuInt.591...87L |s2cid=224877090}}</ref>

<ref name=desantis2015>{{cite journal |last1=DeSantis |first1=L.R.G. |last2=Schubert |first2=B.W. |last3=Schmitt-Linville |first3=E. |last4=Ungar |first4=P. |last5=Donohue |first5=S. |last6=Haupt |first6=R.J. |title=Dental microwear textures of carnivorans from the La Brea Tar Pits, California and potential extinction implications |publisher=Natural History Museum of Los Angeles County |series=Science Series 42 |journal=Contributions in Science |issue=A Special Volume Entitled la Brea and Beyond: The Paleontology of Asphalt-Preserved Biotas in Commemoration of the 100th Anniversary of the Natural History Museum of Los Angeles County's Excavations at Rancho la Brea |editor=John M. Harris |date=September 15, 2015 |pages=37–52 |url= https://www.researchgate.net/publication/282253545}}</ref>

<ref name=dundas1999>{{cite journal |last1=Dundas |first1=R.G. |year=1999 |title=Quaternary records of the dire wolf, ''Canis dirus'', in North and South America |url=http://www.fresnostate.edu/csm/ees/documents/facstaff/dundas/publication/Dundas-1999.pdf |journal=Boreas |volume=28 |issue=3 |pages=375–385 |doi=10.1111/j.1502-3885.1999.tb00227.x |bibcode=1999Borea..28..375D |s2cid=129900134 |access-date=2015-08-28 |archive-date=2020-09-27 |archive-url=https://web.archive.org/web/20200927071042/http://www.fresnostate.edu/csm/ees/documents/facstaff/dundas/publication/Dundas-1999.pdf }}</ref>

<ref name=earle1987>{{cite journal |last1=Earle |first1=M. |title=A flexible body mass in social carnivores |journal=[[The American Naturalist]] |volume=129 |issue=5 |year=1987 |pages=755–760 |doi=10.1086/284670|bibcode=1987ANat..129..755E |s2cid=85236511 }}</ref>

<ref name=elias2016>{{cite book |doi=10.1016/B978-0-12-409548-9.10283-0 |chapter=Late Pleistocene Megafaunal Extinctions |title=Reference Module in Earth Systems and Environmental Sciences |year=2016 |last1=Elias |first1=S.A. |last2=Schreve |first2=D. |isbn=978-0-12-409548-9 |url=https://pure.royalholloway.ac.uk/portal/files/1398773/Article_318_Late_Pleistocene_megafaunal_extinctions.pdf |pages=3202–3217 |s2cid=130031864 |archive-url=https://web.archive.org/web/20161220173549/https://pure.royalholloway.ac.uk/portal/files/1398773/Article_318_Late_Pleistocene_megafaunal_extinctions.pdf |archive-date=2016-12-20 }}</ref>

<ref name=flower2014>{{cite journal |doi=10.1016/j.quascirev.2014.04.015 |title=An investigation of palaeodietary variability in European Pleistocene canids |journal=Quaternary Science Reviews |volume=96 |pages=188–203 |year=2014 |last1=Flower |first1=Lucy O.H. |last2=Schreve |first2=Danielle C. |bibcode=2014QSRv...96..188F}}</ref>

<ref name=frick1930>{{cite journal |last1=Frick |first1=C. |title=Alaska's frozen fauna |journal=[[Natural History (magazine)|Natural History]] |issue=30 |year=1930 |pages=71–80}}</ref>

<ref name=fox2003>{{cite journal |last1=Fox-Dobbs |first1=K. |last2=Koch |first2=P. L. |last3=Clementz |first3=M. T. |title=Lunchtime at La Brea: isotopic reconstruction of ''Smilodon fatalis'' and ''Canis dirus'' dietary patterns through time |journal=[[Journal of Vertebrate Paleontology]] |volume=23 |issue=3, Supplement |year=2003 |pages=51A |doi=10.1080/02724634.2003.10010538|s2cid=220410105 }}</ref>

<ref name=fox2007>{{cite journal |doi=10.1139/Z07-018 |title=Carnivore-specific stable isotope variables and variation in the foraging ecology of modern and ancient wolf populations: Case studies from Isle Royale, Minnesota, and La Brea |journal=[[Canadian Journal of Zoology]] |volume=85 |issue=4 |pages=458–471 |year=2007 |last1=Fox-Dobbs |first1=K. |last2=Bump |first2=J.K. |last3=Peterson |first3=R.O. |last4=Fox |first4=D.L. |last5=Koch |first5=P.L. |bibcode=2007CaJZ...85..458F |url=https://websites.pmc.ucsc.edu/~pkoch/pdfs/Koch%20papers/2007/Fox-Dobbs%20et%2007%20CJZ%2085-458/Fox-Dobbs%20et%2007%20CJZ%2085-458.pdf |access-date=6 May 2017 |archive-date=9 August 2017 |archive-url=https://web.archive.org/web/20170809130357/https://websites.pmc.ucsc.edu/~pkoch/pdfs/Koch%20papers/2007/Fox-Dobbs%20et%2007%20CJZ%2085-458/Fox-Dobbs%20et%2007%20CJZ%2085-458.pdf }}</ref>

<ref name=geist1987>{{cite journal |doi=10.1139/z87-171 |title=On speciation in Ice Age mammals, with special reference to cervids and caprids |journal=Canadian Journal of Zoology |volume=65 |issue=5 |pages=1067–1084 |year=1987 |last1=Geist |first1=Valerius|bibcode=1987CaJZ...65.1067G }}</ref>

<ref name=geist1998>{{cite book |last1=Geist |first1=Valerius |title=Deer of the World: Their Evolution, Behaviour, and Ecology |publisher=[[Stackpole Books]] |location=Mechanicsburg, Pennsylvania |edition=1 |year=1998 |page=10 |url=https://books.google.com/books?id=bcWZX-IMEVkC&pg=PA10 |access-date=1 May 2017 |isbn=978-0-8117-0496-0}}</ref>

<ref name=gold2014>{{cite journal |doi=10.1002/ece3.928 |pmid=24634719 |title=Attempted DNA extraction from a Rancho La Brea Columbian mammoth (''Mammuthus columbi''): Prospects for ancient DNA from asphalt deposits |journal=Ecology and Evolution |volume=4 |issue=4 |pages=329–36 |year=2014 |last1=Gold |first1=David A. |last2=Robinson |first2=Jacqueline |last3=Farrell |first3=Aisling B. |last4=Harris |first4=John M. |last5=Thalmann |first5=Olaf |last6=Jacobs |first6=David K. |pmc=3936381|bibcode=2014EcoEv...4..329G }}</ref>

<ref name=goulet1993>{{cite thesis |last1=Goulet |first1=G. D. |title=Comparison of temporal and geographical skull variation among Nearctic, modern, Holocene, and late Pleistocene gray wolves (''Canis lupus'') and selected ''Canis'' |type=Master's thesis |publisher=University of Manitoba, Winnipeg |year=1993 |pages=1–116}}</ref>

<ref name=graham1987>{{cite book |last1=Graham |first1=R. W. |last2=Mead |first2=J. I. |chapter=Environmental fluctuations and evolution of mammalian faunas during the last deglaciation in North America |title=North America and Adjacent Oceans During the Last Deglaciation |editor1-last=Ruddiman |editor1-first=W. F. |editor2-last=Wright |editor2-first=H. E. |publisher=Geological Society of America K–3, Boulder, Colorado |year=1987 |pages=371–402 |isbn=978-0-8137-5203-7}}</ref>

<ref name=hartstone2015>{{cite journal |last1=Hartstone-Rose |first1=Adam |last2=Dundas |first2=Robert G. |last3=Boyde |first3=Bryttin |last4=Long |first4=Ryan C. |last5=Farrell |first5=Aisling B. |last6=Shaw |first6=Christopher A. |title=The Bacula of Rancho La Brea |publisher=Natural History Museum of Los Angeles County |series=Science Series 42 |journal=Contributions in Science |issue=A Special Volume Entitled la Brea and Beyond: The Paleontology of Asphalt-Preserved Biotas in Commemoration of the 100th Anniversary of the Natural History Museum of Los Angeles County's Excavations at Rancho la Brea |editor=John M. Harris |date=September 15, 2015|pages=53–63}}</ref>

<ref name=hester1960>{{cite journal |doi=10.2307/277160 |jstor=277160 |title=Late Pleistocene Extinction and Radiocarbon Dating|journal=[[American Antiquity]] |volume=26 |issue=1 |pages=58–77 |year=1960 |last1=Hester |first1=Jim J.|s2cid=161116564 }}</ref>

<ref name=hodnett2009>{{cite journal |last=Hodnett |first=John-Paul |author2=Mead Jim |title=Dire Wolf, ''Canis dirus'' (Mammalia; Carnivora; Canidae), from the Late Pleistocene (Rancholabrean) of East-Central Sonora, Mexico |journal=The Southwestern Naturalist |date=March 2009 |volume=54 |issue=1 |pages=74–81 |doi=10.1894/CLG-12.1 |last3=Baez |first3=A.|bibcode=2009SWNat..54...74H |s2cid=84760786 }}</ref>

<ref name=iczncode2017>{{cite web|url=http://www.iczn.org/iczn/index.jsp|title=The Code online (refer Chapter 6, article 23.1)|author=ICZN|date=2017|website=International Code of Zoological Nomenclature online|publisher=International Commission on Zoological Nomenclature|access-date=2017-04-17|archive-url=https://web.archive.org/web/20090524144249/http://www.iczn.org/iczn/index.jsp|archive-date=2009-05-24}}</ref>

<ref name=ipcc2007>{{cite web |author=Intergovernmental Panel on Climate Change (UN) |title=IPCC Fourth Assessment Report: Climate Change 2007 – Palaeoclimatic Perspective |publisher=[[Nobel Foundation]] |year=2007 |url=https://www.ipcc.ch/publications_and_data/ar4/wg1/en/spmsspm-a-palaeoclimatic.html |access-date=2016-12-11 |archive-url=https://web.archive.org/web/20151030211417/http://www.ipcc.ch/publications_and_data/ar4/wg1/en/spmsspm-a-palaeoclimatic.html |archive-date=2015-10-30 }}</ref>

<ref name=janczewski1992>{{cite journal |pmid=1409696 |pmc=50214 |year=1992 |last1=Janczewski |first1=D. N. |title=Molecular phylogenetic inference from saber-toothed cat fossils of Rancho La Brea |journal=Proceedings of the National Academy of Sciences of the United States of America |volume=89 |issue=20 |pages=9769–73 |last2=Yuhki |first2=N. |last3=Gilbert |first3=D. A. |last4=Jefferson |first4=G. T. |last5=O'Brien |first5=S. J. |doi=10.1073/pnas.89.20.9769 |bibcode=1992PNAS...89.9769J|doi-access=free }}</ref>

<ref name=johnson1977>{{cite journal |doi=10.1016/0033-5894(77)90043-6 |title=The Late Quaternary Climate of Coastal California: Evidence for an Ice Age Refugium |journal=Quaternary Research |volume=8 |issue=2 |pages=154–179 |year=1977 |last1=Johnson |first1=Donald Lee |bibcode=1977QuRes...8..154J|s2cid=129072450 }}</ref>

<ref name=Koepfli2015>{{cite journal|last1=Koepfli|first1=K.-P.|last2=Pollinger|first2=J.|last3=Godinho|first3=R.|last4=Robinson|first4=J.|last5=Lea|first5=A.|last6=Hendricks|first6=S.|last7=Schweizer|first7=R. M.|last8=Thalmann|first8=O.|last9=Silva|first9=P.|last10=Fan|first10=Z.|last11=Yurchenko|first11=A. A.|last12=Dobrynin|first12=P.|last13=Makunin|first13=A.|last14=Cahill|first14=J. A.|last15=Shapiro|first15=B.|last16=Álvares|first16=F.|last17=Brito|first17=J. C.|last18=Geffen|first18=E.|last19=Leonard|first19=J. A.|last20=Helgen|first20=K. M.|last21=Johnson|first21=W. E.|last22=O'Brien|first22=S. J.|last23=Van Valkenburgh|first23=B.|last24=Wayne|first24=R. K.|title=Genome-wide Evidence Reveals that African and Eurasian Golden Jackals Are Distinct Species|journal=Current Biology|volume=25|issue=16|pages=2158–65|date=2015-08-17|doi=10.1016/j.cub.2015.06.060|pmid=26234211|doi-access=free|bibcode=2015CBio...25.2158K }}</ref>

<ref name=kurten1980>{{cite book |last1=Kurtén |first1=B. |last2=Anderson |first2=E. |title=Pleistocene mammals of North America |publisher=[[Columbia University Press]], New York |year=1980 |chapter=11-Carnavora |pages=168–172 |isbn=978-0-231-03733-4}}</ref>

<ref name=kurten1984>{{cite book |last1=Kurtén |first1=B. |chapter=Geographic differentiation in the Rancholabrean dire wolf (''Canis dirus'' Leidy) in North America |title=Contributions in Quaternary Vertebrate Paleontology: A Volume in Memorial to John E. Guilday |url=https://archive.org/details/contributionsinq81984geno |publisher=[[Carnegie Museum of Natural History]] |editor1-last=Genoways |editor1-first=H. H. |editor2-last=Dawson |editor2-first=M. R. |series=Special Publication 8 |year=1984 |pages=[https://archive.org/details/contributionsinq81984geno/page/218 218–227] |isbn=978-0-935868-07-4}}</ref>

<ref name=leidy1854>{{cite journal |last1=Leidy |first1=J. |title=Notice of some fossil bones discovered by Mr. Francis A. Lincke, in the banks of the Ohio River, Indiana |journal=Proceedings of the Academy of Natural Sciences of Philadelphia |issue=7 |year=1854 |volume=7 |page=200 |url=https://www.biodiversitylibrary.org/page/1694312#page/221/mode/1up |archive-date=2020-12-01 |access-date=2018-01-14 |archive-url=https://web.archive.org/web/20201201191043/https://www.biodiversitylibrary.org/page/1694312#page/221/mode/1up |url-status=live }}</ref>

<ref name=leidy1858>{{cite journal |last1=Leidy |first1=J. |title=Notice of remains of extinct vertebrata, from the Valley of the Niobrara River, collected during the Exploring Expedition of 1857, in Nebraska, under the command of Lieut. G. K. Warren, U. S. Top. Eng., by Dr. F. V. Hayden, Geologist to the Expedition, Proceedings |journal=Proceedings of the Academy of Natural Sciences of Philadelphia |volume=10 |year=1858 |page=21 |url=https://www.biodiversitylibrary.org/page/26289610#page/41/mode/1up |archive-date=2016-12-01 |access-date=2018-01-14 |archive-url=https://web.archive.org/web/20161201105519/http://www.biodiversitylibrary.org/page/26289610#page/41/mode/1up |url-status=live }}</ref>

<ref name=leidy1869>{{cite journal |last1=Leidy |first1=J. |title=The extinct mammalian fauna of Dakota and Nebraska, including an account of some allied forms from other localities, together with a synopsis of the mammalian remains of North America |journal=Journal of the Academy of Natural Sciences of Philadelphia |volume=7 |year=1869 |page=368 |url=https://www.biodiversitylibrary.org/item/60918#page/374/mode/1up |archive-date=2021-02-02 |access-date=2018-01-14 |archive-url=https://web.archive.org/web/20210202195630/https://www.biodiversitylibrary.org/item/60918#page/374/mode/1up |url-status=live }}</ref>

<ref name=leonard2007>{{cite journal |pmid=17583509 |url=https://websites.pmc.ucsc.edu/~pkoch/pdfs/Koch%20papers/2007/Leonard%20et%2007%20CurBio%2017-1146.pdf |year=2007 |last1=Leonard |first1=J. A. |title=Megafaunal extinctions and the disappearance of a specialized wolf ectomorph |journal=Current Biology |volume=17 |issue=13 |pages=1146–50 |last2=Vilà |first2=C |last3=Fox-Dobbs |first3=K |last4=Koch |first4=P. L. |last5=Wayne |first5=R. K. |last6=Van Valkenburgh |first6=B. |doi=10.1016/j.cub.2007.05.072 |bibcode=2007CBio...17.1146L |s2cid=14039133 |access-date=6 May 2017 |hdl=10261/61282 |hdl-access=free |archive-date=28 December 2016 |archive-url=https://web.archive.org/web/20161228122803/http://www.es.ucsc.edu/~pkoch/pdfs/Koch%20papers/2007/Leonard%20et%2007%20CurBio%2017-1146.pdf }}</ref>

<ref name=leonard2014>{{cite journal |author=Leonard, Jennifer |year=2014 |title=Ecology drives evolution in grey wolves |journal=Evolution Ecology Research |volume=16 |pages=461–473 |url=http://www.evolutionary-ecology.com/open/v16n06/eear2913.pdf |archive-date=2016-04-15 |access-date=2016-12-24 |archive-url=https://web.archive.org/web/20160415155506/http://www.evolutionary-ecology.com/open/v16n06/eear2913.pdf |url-status=live }}</ref>

<ref name=lundelius1972>{{cite journal |last1=Lundelius |first1=E. L. |title=Fossil vertebrates, late Pleistocene Ingleside Fauna, San Patricio County, Texas |journal=Bureau of Economic Geology |volume=Report of Investigations no.77 |year=1972 |pages=1–74}}</ref>

<ref name=lundelius2004>{{cite book |last1=Lundelius |first1=E.L. |last2=Bell |first2=C.J. |title=Late Cretaceous and Cenozoic Mammals of North America: Biostratigraphy and Geochronology |publisher=Columbia University Press |editor=Michael O. Woodburne |chapter=7 The Blancan, Irvingtonian, and Rancholabrean Mammal Ages |year=2004 |page=285 |isbn=978-0-231-13040-0 |chapter-url=https://edocs.uis.edu/druez2/www/publications/Bla%20Irv%20Ranch.pdf |access-date=1 May 2017 |archive-date=8 June 2017 |archive-url=https://web.archive.org/web/20170608233927/https://edocs.uis.edu/druez2/www/publications/Bla%20Irv%20Ranch.pdf }}</ref>

<ref name=mchorse2012>{{cite journal |doi=10.1016/j.palaeo.2012.02.022 |title=The carnivoran fauna of Rancho La Brea: Average or aberrant? |journal=Palaeogeography, Palaeoclimatology, Palaeoecology |volume=329–330 |pages=118–123 |year=2012 |last1=McHorse |first1=Brianna K. |last2=Orcutt |first2=John D. |last3=Davis |first3=Edward B.|bibcode=2012PPP...329..118M }}</ref>

<ref name=marcus1984>{{cite book |last1=Marcus |first1=L. F. |last2=Berger |first2=R. |chapter=The significance of radiocarbon dates for Rancho La Brea |title=Quaternary Extinctions |publisher=University of Arizona Press, Tucson |editor1-first=P. S. |editor1-last=Martin |editor2-first=R. G. |editor2-last=Klein |year=1984 |pages=159–188 |isbn=978-0-8165-0812-9}}</ref>

<ref name=martin1974>{{cite book |last1=Martin |first1=R. A. |first2=S. D. |last2=Webb |year=1974 |chapter=Late Pleistocene mammals from the Devil's Den fauna, Levy County |pages=[https://archive.org/details/pleistocenemamma0000webb/page/114 114–145] |editor-first=S. D. |editor-last=Webb |title=Pleistocene Mammals of Florida |url=https://archive.org/details/pleistocenemamma0000webb |url-access=registration |location=Gainesville |publisher=[[University Press of Florida]] |isbn=978-0-8130-0361-0}}</ref>

<ref name=meachen2016>{{cite journal |doi=10.1002/ece3.2141 |pmid=27252837 |title=Extinct Beringian wolf morphotype found in the continental U.S. has implications for wolf migration and evolution |journal=[[Ecology and Evolution]] |volume= 6 |issue=10 |pages= 3430–8 |year=2016 |last1=Meachen |first1=Julie A. |last2=Brannick |first2=Alexandria L. |last3=Fry |first3=Trent J. |pmc=4870223|bibcode=2016EcoEv...6.3430M }}</ref>

<ref name=mead1996>{{cite book |last1=Mead |first1=J. I. |last2=Manganaro |first2=C. |last3=Repenning |first3=C. A. |last4=Agenbroad |first4=L. D. |title=Palaeoecology and Palaeoenvironments of Late Cenozoic Mammals, Tributes to the Career of C. S. (Rufus) Churcher |publisher=[[University of Toronto Press]], Toronto, Ontario, Canada |editor1-last=Stewart |editor1-first=K. M. |editor2-last=Seymour |editor2-first=K. L. |year=1996 |chapter=Early Rancholabrean mammals from Salamander Cave, Black Hills, South Dakota |pages=458–482 |chapter-url= https://nps.gov/wica/naturescience/abstact-palaeoecology-and-palaeoenvironments-of-late-cenozoic-mammals-early-rancholabrean-mammals-from-salamander-cave-black-hills-south-dakota.htm |isbn=978-0-8020-0728-5 |url-status=live |archive-url=https://web.archive.org/web/20150110234550/http://www.nps.gov/wica/naturescience/abstact-palaeoecology-and-palaeoenvironments-of-late-cenozoic-mammals-early-rancholabrean-mammals-from-salamander-cave-black-hills-south-dakota.htm |archive-date=2015-01-10 }}</ref>

<ref name=mech1966>{{cite book |last=Mech |first=L. David |author-link=L. David Mech |title=The Wolves of Isle Royale |publisher=Fauna of the National Parks of the United States |series=Fauna Series 7 |year=1966 |isbn=978-1-4102-0249-9 |url=https://archive.org/stream/wolvesofisleroya00royal#page/1 |access-date=1 May 2017}}</ref>

<ref name=merriam1912>{{cite journal |last1=Merriam |first1=J. C. |title=The fauna of Rancho La Brea, Part II. Canidae |journal=Memoirs of the University of California |volume=1 |year=1912 |pages=217–273 |url=https://archive.org/stream/faunaofrancholab02merr/faunaofrancholab02merr_djvu.txt}}</ref>

<ref name=merriam1918>{{cite journal |last1=Merriam |first1=J.C. |title=Note on the systematic position of the wolves of the Canis dirus group |journal=Bulletin of the Department of Geology of the University of California |volume=10 |year=1918 |page=533 |url=https://www.biodiversitylibrary.org/item/139018#page/686/mode/1up |archive-date=2021-01-29 |access-date=2018-01-14 |archive-url=https://web.archive.org/web/20210129220446/https://www.biodiversitylibrary.org/item/139018#page/686/mode/1up |url-status=live }}</ref>

<ref name=moratto1984>{{cite book |last1=Moratto |first1=Michael J. |title=California Archaeology |publisher=[[Academic Press]], Orlando, Florida |year=1984 |page=89 |url=https://books.google.com/books?id=jUm0BQAAQBAJ&pg=PA89 |access-date=1 May 2017 |isbn=978-0-12-506180-3}}</ref>

<ref name=nowak84>{{Harvnb|Nowak|1979|pp=84}}</ref>

<ref name=nowak93>{{Harvnb|Nowak|1979|pp=93}}</ref>

<ref name=nowak102>{{Harvnb|Nowak|1979|pp=102}}</ref>

<ref name=nowak106>{{Harvnb|Nowak|1979|pp=106–108}}</ref>

<ref name=nowak116>{{Harvnb|Nowak|1979|pp=116–117}}</ref>

<ref name=nowak2002>{{cite journal |doi=10.1007/BF03194151 |title=The systematic status of the Italian wolf ''Canis lupus'' |journal=Acta Theriologica |volume=47 |issue=3 |pages=333–338 |year=2002 |last1=Nowak |first1=Ronald M. |last2=Federoff |first2=Nicholas E. (Brusco)|bibcode=2002AcTh...47..333N |s2cid=366077 }}</ref>

<ref name=nowak2003>{{cite book |editor-last=Mech |editor-first=L. David |editor2-last=Boitani |editor2-first=Luigi |title=Wolves: Behaviour, Ecology and Conservation |publisher=[[University of Chicago Press]] |year=2003 |isbn=978-0-226-51696-7 |chapter=9-Wolf evolution and taxonomy |author=R.M. Nowak|pages=242–243}}</ref>

<ref name=okeefe2008>{{cite journal |last1=O'Keefe |first1=F.R. |title=Population-level response of the dire wolf, ''Canis dirus'', to climate change in the upper Pleistocene |journal=Journal of Vertebrate Paleontology |volume=28 |year=2008 |page=122A |doi=10.1080/02724634.2008.10010459|s2cid=220405736 }}</ref>

<ref name=okeefe2009>{{cite journal |last1=O'Keefe |first1=F.R. |last2=Fet |first2=E.V. |last3=Harris |first3=J.M. |title=Compilation, calibration, and synthesis of faunal and floral radiocarbon dates, Rancho La Brea, California |journal=Contributions in Science |volume=518 |year=2009 |pages=1–16 |doi=10.5962/p.226783 |s2cid=128107590 |url=https://nhm.org/site/sites/default/files/pdf/contrib_science/CS518.pdf |access-date=2017-06-28 |archive-url=https://web.archive.org/web/20170703194412/https://nhm.org/site/sites/default/files/pdf/contrib_science/CS518.pdf |archive-date=2017-07-03 }}</ref>

<ref name=okeefe2014>{{cite journal |last1=O'Keefe |first1=F.Robin |last2=Binder |first2=Wendy J. |last3=Frost |first3=Stephen R. |last4=Sadlier |first4=Rudyard W. |last5=Van Valkenburgh |first5=Blaire |title=Cranial morphometrics of the dire wolf, ''Canis dirus'', at Rancho La Brea: temporal variability and its links to nutrient stress and climate |journal=Palaeontologia Electronica |volume=17 |issue=1 |year=2014 |pages=1–24 |url=http://www.palaeo-electronica.org/content/2014/723-canis-dirus-craniometrics |archive-date=2018-12-16 |access-date=2016-05-17 |archive-url=https://web.archive.org/web/20181216130648/http://www.palaeo-electronica.org/content/2014/723-canis-dirus-craniometrics |url-status=live }}</ref>

<ref name=page>{{cite web |author=Page Museum |title=View the collections at Rancho La Brea |website=The Natural History Museum of Los Angeles County Foundation |access-date=19 December 2016 |url=http://www.nhm.org/site/research-collections/rancho-la-brea/view-collections |archive-url=https://web.archive.org/web/20170125214327/http://www.nhm.org/site/research-collections/rancho-la-brea/view-collections |archive-date=25 January 2017 }}</ref>

<ref name=perri2016>{{cite journal |doi=10.1016/j.jas.2016.02.003 |title=A wolf in dog's clothing: Initial dog domestication and Pleistocene wolf variation |journal=[[Journal of Archaeological Science]] |volume=68 |pages=1–4 |year=2016 |last1=Perri |first1=Angela|bibcode=2016JArSc..68....1P }}</ref>

<ref name=Perri2021>{{cite journal|doi=10.1038/s41586-020-03082-x|title=Dire wolves were the last of an ancient New World canid lineage|year=2021|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|last12=Antipina|first12=Ekaterina E.|last13=Bover|first13=Pere|last14=Brace|first14=Selina|last15=Carmagnini|first15=Alberto|last16=Carøe|first16=Christian|last17=Samaniego Castruita|first17=Jose A.|last18=Chatters|first18=James C.|last19=Dobney|first19=Keith|last20=Dos Reis|first20=Mario|last21=Evin|first21=Allowen|last22=Gaubert|first22=Philippe|last23=Gopalakrishnan|first23=Shyam|last24=Gower|first24=Graham|last25=Heiniger|first25=Holly|last26=Helgen|first26=Kristofer M.|last27=Kapp|first27=Josh|last28=Kosintsev|first28=Pavel A.|last29=Linderholm|first29=Anna|last30=Ozga|first30=Andrew T.|last31=Presslee|first31=Samantha|last32=Salis|first32=Alexander T.|last33=Saremi|first33=Nedda F.|last34=Shew|first34=Colin|last35=Skerry|first35=Katherine|last36=Taranenko|first36=Dmitry E.|last37=Thompson|first37=Mary|last38=Sablin|first38=Mikhail V.|last39=Kuzmin|first39=Yaroslav V.|last40=Collins|first40=Matthew J.|last41=Sinding|first41=Mikkel-Holger S.|last42=Gilbert|first42=M. Thomas P.|author-link42=Marcus Thomas Pius Gilbert|last43=Stone|first43=Anne C.|last44=Shapiro|first44=Beth|last45=Van Valkenburgh|first45=Blaire|author-link45=Blaire Van Valkenburgh|last46=Wayne|first46=Robert K.|last47=Larson|first47=Greger|last48=Cooper|first48=Alan|last49=Frantz|first49=Laurent A. F.|journal=Nature|volume=591|issue=7848|pages=87–91|pmid=33442059|bibcode=2021Natur.591...87P|s2cid=231604957|url=https://ora.ox.ac.uk/objects/uuid:c087f6d0-e084-4558-be53-d503697ce140|archive-date=2022-12-31|access-date=2021-08-02|archive-url=https://web.archive.org/web/20221231112007/https://ora.ox.ac.uk/objects/uuid:c087f6d0-e084-4558-be53-d503697ce140|url-status=live}}</ref>

<ref name=prevosti2010>{{cite journal|doi=10.1111/j.1096-0031.2009.00298.x|title=Phylogeny of the large extinct South American Canids (Mammalia, Carnivora, Canidae) using a "total evidence" approach|journal=Cladistics|volume=26|issue=5|pages=456–481|year=2010|last1=Prevosti|first1=Francisco J.|pmid=34875763|s2cid=86650539|url=https://www.academia.edu/1455344|doi-access=free|archive-date=2023-04-07|access-date=2017-12-15|archive-url=https://web.archive.org/web/20230407055116/https://www.academia.edu/1455344|url-status=live}} Refer page 472</ref>

<ref name=scott2016>{{cite journal |doi=10.7717/peerj.2151 |pmid=27366649 |pmc=4924133 |title=First records of ''Canis dirus'' and ''Smilodon fatalis'' from the late Pleistocene Tule Springs local fauna, upper Las Vegas Wash, Nevada |journal=PeerJ |volume=4 |article-number=e2151 |year=2016 |last1=Scott |first1=Eric |last2=Springer |first2=Kathleen B. |doi-access=free |bibcode=2016PeerJ...4.2151S }}</ref>

<ref name=sellards1916>{{cite journal |last1=Sellards |first1=E.H. |title=Human remains and associated fossils from the Pleistocene of Florida |journal=Annual Report of the Florida Geological Survey |volume=8 |year=1916 |page=152 |url=https://www.biodiversitylibrary.org/item/24960#page/180/mode/1up |archive-date=2021-02-01 |access-date=2018-01-14 |archive-url=https://web.archive.org/web/20210201160158/https://www.biodiversitylibrary.org/item/24960#page/180/mode/1up |url-status=live }}</ref>

<ref name=sorkin2008>{{cite journal |doi=10.1111/j.1502-3931.2007.00091.x |title=A biomechanical constraint on body mass in terrestrial mammalian predators |journal=Lethaia |volume=41 |issue=4 |pages=333–347 |year=2008 |last1=Sorkin |first1=Boris|bibcode=2008Letha..41..333S }}</ref>

<ref name=stock1948>{{cite journal |last1=Stock |first1=Chester |last2=Lance |first2=John F. |title=The Relative Lengths of Limb Elements in ''Canis dirus'' |journal=Bulletin of the Southern California Academy of Sciences |volume=47 |issue=3 |year=1948 |pages=79–84 |url=https://www.biodiversitylibrary.org/page/34150894#page/271/mode/1up |archive-date=2018-10-10 |access-date=2018-01-14 |archive-url=https://web.archive.org/web/20181010024946/https://www.biodiversitylibrary.org/page/34150894#page/271/mode/1up |url-status=live }}</ref>

<ref name=stevenson1978>{{cite book |first=Marc |last=Stevenson |year=1978 |title=Wolf and Man: Evolution in Parallel |editor1-first=Roberta L. |editor1-last=Hall |editor2-first=Henry S. |editor2-last=Sharp |publisher=Academic Press |location=New York |chapter=9 |page=180 |chapter-url=https://books.google.com/books?id=tj60BQAAQBAJ&pg=PA180 |access-date=1 May 2017 |isbn=978-0-12-319250-9}}</ref>

<ref name=stock1992>{{cite book |last1=Stock |first1=C. |title=Rancho La Brea: A Record of Pleistocene Life in California |publisher=Natural History Museum of Los Angeles County |series=Science Series |edition=7 |year=1992 |pages=1–113 |isbn=978-0-938644-30-9}}</ref>

<ref name=tedford4>{{Harvnb|Tedford|Wang|Taylor|2009|pp=4}}</ref>

<ref name=tedford146>{{Harvnb|Tedford|Wang|Taylor|2009|pp=146–148}}</ref>

<ref name=tedford181>{{Harvnb|Tedford|Wang|Taylor|2009|pp=181}}</ref>

<ref name=tedford325>{{Harvnb|Tedford|Wang|Taylor|2009|pp=325}}</ref>

<ref name=therrien2005>{{cite journal |doi=10.1017/S0952836905007430 |title=Mandibular force profiles of extant carnivorans and implications for the feeding behaviour of extinct predators |journal=Journal of Zoology |volume=267 |issue=3 |pages=249–270 |year=2005 |last1=Therrien |first1=François}}</ref>

<ref name=troxell1915>{{cite journal |last1=Troxell |first1=E.L. |title=Vertebrate fossils of Rock Creek, Texas |journal=American Journal of Science |volume=189 |issue=234 |year=1915 |pages=613–618 |url=https://www.biodiversitylibrary.org/item/124986#page/675/mode/1up|doi=10.2475/ajs.s4-39.234.613 |bibcode=1915AmJS...39..613T }}</ref>

<ref name=tseng2010>{{cite journal |doi=10.1002/jmor.10881 |pmid=20799339 |title=Cranial functional morphology of fossil dogs and adaptation for durophagy in ''Borophagus'' and ''Epicyon'' (Carnivora, Mammalia) |journal=[[Journal of Morphology]] |volume=271 |issue=11 |pages=1386–98 |year=2010 |last1=Tseng |first1=Zhijie Jack |last2=Wang |first2=Xiaoming|bibcode=2010JMorp.271.1386T |s2cid=7150911 }}</ref>

<ref name=valkenburg1987>{{cite journal |doi=10.1111/j.1469-7998.1987.tb02910.x |title=Canine tooth strength and killing behaviour in large carnivores |journal=Journal of Zoology |volume=212 |issue=3 |pages=379–397 |year=1987 |last1=Valkenburgh |first1=B. Van |last2=Ruff |first2=C. B.}}</ref>

<ref name=valkenburgh1988>{{cite journal |last1=Van Valkenburgh |first1=B. |year=1988 |title=Incidence of tooth breakage among large predatory mammals |journal=American Naturalist |volume=131 |issue=2 |pages=291–302 |doi=10.1086/284790|bibcode=1988ANat..131..291V |s2cid=222330098 }}</ref>

<ref name=valkenburgh1993a>{{cite journal |last1=Van Valkenburgh |first1=Blaire |last2=Hertel |first2=Fritz |title=Tough Times at La Brea: Tooth Breakage in Large Carnivores of the Late Pleistocene |journal=Science |series=New Series |volume=261 |issue=5120 |year=1993 |pages=456–459 |url=http://www.cof.orst.edu/leopold/class-reading/Van%20Valkenburgh%20and%20Hertel%201993.pdf |doi=10.1126/science.261.5120.456 |pmid=17770024 |bibcode=1993Sci...261..456V |s2cid=39657617 |archive-date=2016-12-20 |access-date=2016-05-06 |archive-url=https://web.archive.org/web/20161220115240/http://www.cof.orst.edu/leopold/class-reading/Van%20Valkenburgh%20and%20Hertel%201993.pdf |url-status=live }}</ref>

<ref name=valkenburgh1993b>{{cite book |last1=Van Valkenburgh |first1=B. |last2=Koepfli |first2=K.-P. |title=Mammals as Predators |publisher=Oxford University Press |location=Oxford |editor1-first=N. |editor1-last=Dunston |editor2-first=J. L. |editor2-last=Gorman |year=1993 |chapter=Cranial and dental adaptations to predation in canids |pages=15–37}}</ref>

<ref name=valkenburgh1998>{{cite book |last1=Van Valkenburgh |first1=B. |title=Quaternary Paleozoology in the Northern Hemisphere |publisher=Illinois State Museum Scientific Papers, Springfield |editor1-first=J. J. |editor1-last=Saunders |editor2-first=B. W. |editor2-last=Styles |editor3-first=G. F. |editor3-last=Baryshnikov |year=1998|chapter=The decline of North American predators during the late Pleistocene|pages=357–374|isbn=978-0-89792-156-5}}</ref>

<ref name=valkenburgh2002>{{cite journal |doi=10.1671/0272-4634(2002)022[0164:SDSBAI]2.0.CO;2 |year=2002 |volume=22 |pages=164–169 |title=Sexual dimorphism, social behavior, and intrasexual competition in large Pleistocene carnivorans |journal=Journal of Vertebrate Paleontology |last1=Van Valkenburgh |first1=Blaire |last2=Sacco |first2=Tyson|s2cid=86156959 }}</ref>

<ref name=valkenburgh2008b>{{cite journal |doi=10.1111/j.1095-8312.2008.01108.x |title=Costs of carnivory: Tooth fracture in Pleistocene and Recent carnivorans |journal=[[Biological Journal of the Linnean Society]] |volume=96 |pages=68–81 |year=2008 |last1=Van Valkenburgh |first1=Blaire |url=https://zenodo.org/record/890150 |doi-access=free |archive-date=2020-01-21 |access-date=2019-09-06 |archive-url=https://web.archive.org/web/20200121183613/https://zenodo.org/record/890150 |url-status=live }}</ref>

<ref name=wang20>{{Harvnb|Wang|Tedford|2008|pp=20}}</ref>

<ref name=wang49>{{Harvnb|Wang|Tedford|2008|pp=49}}</ref>

<ref name=wang60>{{Harvnb|Wang|Tedford|2008|pp=60}}</ref>

<ref name=wang143>{{Harvnb|Wang|Tedford|2008|pp=143–144}}</ref>

<ref name=wang148>{{Harvnb|Wang|Tedford|2008|pp=148–150}}</ref>

<ref name=Wang-Tedford_2008>{{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=2014-05-24 |archive-date=2022-01-29 |archive-url=https://web.archive.org/web/20220129005203/https://www.naturalhistorymag.com/features/15771/how-dogs-came-to-run-the-world |url-status=live }}</ref>

<ref name=wang1990>{{cite journal |last1=Wang |first1=X. |title=Pleistocene dire wolf remains from the Kansas River with notes on dire wolves in Kansas |journal=Occasional Papers of the Museum of Natural History, University of Kansas |volume=137 |year=1990 |pages=1–7}}</ref>

<ref name=webb1991>{{cite journal |last1=Webb |first1=S.D. |year=1991 |title=Ecogeography and the great American interchange |journal=[[Paleobiology (journal)|Paleobiology]] |volume=17 |issue=3 |pages=266–280 |doi=10.1017/S0094837300010605|bibcode=1991Pbio...17..266W |s2cid=88305955 }}</ref>

<ref name=wroe2005>{{cite journal |doi=10.1098/rspb.2004.2986 |title=Bite club: Comparative bite force in big biting mammals and the prediction of predatory behaviour in fossil taxa |journal=Proceedings of the Royal Society B: Biological Sciences |volume=272 |issue=1563 |pages=619–25 |year=2005 |last1=Wroe |first1=S. |last2=McHenry |first2=C. |last3=Thomason |first3=J. |pmid=15817436 |pmc=1564077}}</ref>

<ref name=yukon2017>{{cite web |url=http://www.env.gov.yk.ca/animals-habitat/mammals/documents/Grey_wolf.pdf |title=Gray wolf (in the Yukon) |year=2017 |website=Environment Yukon |publisher=Government of Canada |access-date=18 April 2017 |archive-date=25 July 2019 |archive-url=https://web.archive.org/web/20190725164111/http://www.env.gov.yk.ca/animals-habitat/mammals/documents/Grey_wolf.pdf |url-status=live }}</ref>

<ref name=Zrzavy2018>{{cite journal|doi=10.1111/zsc.12293|title=Phylogeny of the Caninae (Carnivora): Combining morphology, behaviour, genes and fossils|year=2018|last1=Zrzavý|first1=Jan|last2=Duda|first2=Pavel|last3=Robovský|first3=Jan|last4=Okřinová|first4=Isabela|last5=Pavelková Řičánková|first5=Věra|journal=Zoologica Scripta|volume=47|issue=4|pages=373–389|s2cid=90592618}}</ref>
}}

==Works cited==
* {{cite journal|last1=Berta|first1=A.|author-link1=Annalisa Berta|title=Quaternary evolution and biogeography of the large South American Canidae (Mammalia: Carnivora) |journal=University of California Publications in Geological Sciences|issue=132|year=1988|url=https://books.google.com/books?id=LD5BVM_jG7gC|isbn=978-0-520-09960-9}}
* {{cite book|last1=Nowak|first1=Ronald M.|title=North American Quaternary Canis |publisher=Monograph of the Museum of Natural History, University of Kansas |series=6 |year=1979|isbn=978-0-89338-007-6 |doi=10.5962/bhl.title.4072|url=https://www.biodiversitylibrary.org/item/22683#page/118/mode/1up |access-date=1 May 2017}}
* {{cite journal|last1=Tedford|first1=Richard H.|author-link1=Richard H. Tedford|last2=Wang|first2=Xiaoming|author-link2=Xiaoming Wang (paleontologist)|last3=Taylor|first3=Beryl E.|year=2009|title=Phylogenetic Systematics of the North American Fossil Caninae (Carnivora: Canidae)|doi=10.1206/574.1|volume=325|journal=[[Bulletin of the American Museum of Natural History]] |pages=1–218|url=http://digitallibrary.amnh.org/bitstream/2246/5999/1/B325.pdf|hdl=2246/5999|s2cid=83594819}}
* {{cite book|last1=Wang|first1=Xiaoming|author-link1=Xiaoming Wang (paleontologist)|last2=Tedford|first2=Richard H.|author-link2=Richard H. Tedford|title=Dogs: Their Fossil Relatives and Evolutionary History|publisher=[[Columbia University Press]], New York|year=2008|pages=1–232|isbn=978-0-231-13529-0|url={{Google books|plainurl=yes|id=LnWdpK7ctI0C|page=}}}}

==External links==
* For younger readers – [https://books.google.com/books?id=yV9953KbfoIC&pg=PA3 Dire Wolf] by Marc Zabludoff, Marshall Cavendish, 2009
* [http://www.museum.state.il.us/exhibits/larson/canis.html Information on the dire wolf from the Illinois State Museum]
* [http://faculty.evansville.edu/ck6/bstud/direwolf.html The Evansville Dire Wolf]

{{Canidae extinct nav|W.}}
{{Authority control}}
{{Taxonbar|from=Q496689}}

[[Category:Dire wolf| ]]
[[Category:Canina (subtribe)]]
[[Category:Prehistoric canines]]
[[Category:Pleistocene carnivorans]]
[[Category:Holocene extinctions]]
[[Category:Pleistocene first appearances]]
[[Category:Pleistocene mammals of North America]]
[[Category:Pleistocene mammals of South America]]
[[Category:Pleistocene mammals of Asia]]
[[Category:Fossil taxa described in 1858]]
[[Category:Mammals described in 1858]]
[[Category:Apex predators]]
[[Category:Taxa named by Joseph Leidy]]