| Xenocyon Temporal range:Pliocene to MiddlePleistocene | |
|---|---|
 | |
| Canis (Xenocyon)falconeri skull | |
Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Mammalia |
| Order: | Carnivora |
| Family: | Canidae |
| Genus: | Canis |
| Subgenus: | †Xenocyon Kretzoi, 1938[1] |
| Species | |
 | Parts of this article (those related to systematics concerning recent specieshttps://doi.org/10.1016/j.cub.2015.06.060) need to beupdated. Please help update this article to reflect recent events or newly available information.(February 2023) |
Xenocyon ("strange dog") is an extinct group of canids, either considered a distinctgenus[2] or asubgenus ofCanis. The group includesCanis (Xenocyon)africanus,Canis (Xenocyon)antonii andCanis (Xenocyon)falconeri that gave rise toCanis (Xenocyon)lycanoides.[3] ThehypercarnivorousXenocyon is thought to be closely related and possibly ancestral to moderndhole and theAfrican wild dog,[4]: p149 as well as the insularSardinian dhole.[5]
_Fig._1.png)
Xenocyon is proposed as a subgenus ofCanis namedCanis (Xenocyon).[3] Onetaxonomic authority proposes that as part of this subgenus, the group namedCanis (Xenocyon) ex gr.falconeri (ex gr. meaning "of the group including") would include all of the large hypercarnivorous canids that inhabited theOld World during the Late Pliocene–Early Pleistocene:Canis (Xenocyon)africanus inAfrica,Canis (Xenocyon)antonii inAsia andCanis (Xenocyon)falconeri inEurope. Further, these three could be regarded as extreme geographical variations within the onetaxon. This group was hypercanivorous, had a large body size that is comparable with the northern populations of the moderngray wolf (Canis lupus) and are characterized by a shortneurocranium relative to their skull size.[3]
The ancestral condition for canids is to have five toes on their forelimbs, but by theEarly Pleistocene this lineage had reduced this to four, which is also a characteristic feature of the modernAfrican wild dog (Lycaon pictus).[6][7] The African wild dog cannot be positively identified in thefossil record of eastern Africa until the middle Pleistocene,[8] and identifying the oldestLycaon fossil is difficult because these are hard to distinguish fromCanis (Xenocyon)africanus.[7] Some authors considerCanis (Xenocyon)lycanoides as ancestral to the generaLycaon andCuon.[9][10][11][4]: p149 Therefore, one taxonomic authority has proposed that all of theCanis (Xenocyon) group should be reclassified into the genusLycaon. This would form threechronospecies:Lycaon falconeri during theLate Pliocene of Eurasia,Lycaon lycaonoides during the Early Middle Pleistocene of Eurasia and Africa andLycaon pictus from the Middle Late Pleistocene to present.[6]
The species was originally namedCanis africanus (Pohle 1928)[12] but was later reassigned asCanis (Xenocyon)africanus. It existed during theLate Pliocene andEarly Pleistocene of Africa.[3]
The species was originally namedCanis antonii (Zdansky 1924)[13] but was later reassigned asCanis (Xenocyon)antonii. It existed during the late Pliocene and Early Pleistocene of Asia.[3] The name was applied to Late Pliocene fossils of canids with hypercarnivorous dentition that were found in China at the sites Loc. 33 (Yangshao,Henan), Loc. 64 (Zhili Province) andFancun,Shanxi Province.[14] The species was recorded in Europe asCanis (Xenocyon)falconeri.[6]
UpperValdarno is the name given to that part of theArno valley situated in the provinces ofFlorence andArezzo, Italy. The region is bounded by thePratomagno mountain range to the north and east and by the Chianti mountains to the south and west. The Upper Valdarno Basin has provided the remains of three fossil canid species dated to the LateVillafranchian era of Europe 1.9-1.8 million years ago that arrived with a faunal turnover around that time (Early Pleistocene). It is here that the Swiss paleontologistCharles Immanuel Forsyth Major discovered Falconer's wolf (Canis falconeri) (Forsyth Major 1877).[15] The species was later reassigned asCanis (Xenocyon)falconeri,[3] but was later regarded as the European arrival ofCanis (Xenocyon)antonii.[6] The species gave rise toCanis (Xenocyon)lycanoides.[3]
_fig._4_Xenocyon_lycaonoides.png)
The species was originally namedXenocyon lycaonoides (Kretzoi 1938)[1] but was later reassigned asCanis (Xenocyon)lycanoides.[3]
Another view is thatlycaonoides andfalconeri should be classified under genusLycaon, to give the descent of 3 chronospecies:L. falconeri Late Pliocene of Eurasia →L. lycaonoides Early Pleistoceneand the beginning of theMiddle Pleistocene of Eurasia and Africa →L. pictus Middle Pleistocene to the present day.[6]
The diversity of the wolf-sized species decreased by the end of the Early Pleistocene and into the Middle Pleistocene of Europe and Asia. These wolves include the large hypercarnivorousCanis (Xenocyon)lycaonoides that was comparable in size with the modern gray wolf (C. lupus) northern populations and the small Mosbach wolf (C. mosbachensis) that is comparable in size to the modernIndian wolf (C. l. pallipes). Both types of wolves could be found existing from England and Greece across Europe to the high latitudes of Siberia through to Transbaikalia, Tajikistan, Mongolia, and China.[14] Remains of both canid species are also found inUbeidiya, in the southern Levant.[16] The true gray wolves did not make an appearance until the end of the Middle Pleistocene, 500-300 thousand years ago.[14]
Fossil evidence to dated 1.8 million years ago fromDmanisi, Georgia in the southern Caucasus suggests that they were cooperative hunters which cared for their sick, injured and disabled pack members similar to the modern grey wolf.[17]
It preyed onantelope,deer,elephant calves,aurochs,baboons,wild horses and possiblyhumans. It was probably the ancestor of theAfrican wild dog (Lycaon pictus) and possibly thedhole (Cuon alpinus) of southeastern Asia, the extinctSardinian dhole (Cynotherium sardous)[6][18][9] and perhaps two extinct Javanese dogs (Merriam's dog (Megacyon merriami) and the Trinil dog (Mececyon trinilensis)).[19][20]
Just before the appearance of thedire wolf (Aenocyon dirus), North America was invaded by the genusXenocyon, which was as large asA. dirus and more hypercarnivorous. The fossil record shows them as rare and it is assumed that they could not compete with the newly derivedA. dirus.[4] These have been ascribed toXenocyon lycaonoides, withXenocyon texanus from as far south as Texas as itstaxonomic synonym.[21]
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