Canis dirus, [44] or as it is now widely recognized, Aenocyon dirus, lived in the late Pleistocene to early Holocene in North and South America. [45] 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 – a new species splitting from an older one – could occur together during periods of climatic extremes. [46] [47] Gloria D. Goulet agreed with Martin and further proposed that this hypothesis might explain the sudden appearance of A. dirus in North America, and that because of the similarities in their skull shapes that C. lupus gave rise to the A. dirus hypermorph due to abundant game, a stable environment, and large competitors. [48] Nowak, Kurten and Berta disagreed with Goulet and proposed that A. dirus was not derived from C. lupus. [23] [34] [49] The three noted paleontologists Xiaoming Wang, R. H. Tedford and R. M. Nowak have all proposed that A. dirus had evolved from C. armbrusteri, [50] [36] :181 with Nowak stating that there were specimens from Cumberland Cave, Maryland, that indicated C. armbrusteri diverging into A. dirus. [22] :p243 [51] The two taxa share a number of characteristics ( synapomorphy), which suggests an origin of A. dirus in the late Irvingtonian in the open terrain in the midcontinent, and then later expanding eastward and displacing its ancestor C. armbrusteri. [36] :181 Xu, Yu; Yang, Biao; Dou, Liang (2015). "Local villagers' perceptions of wolves in Jiuzhaigou County, western China". PeerJ. 3: e982. doi: 10.7717/peerj.982. PMC 4465947. PMID 26082870.

He said, 'To find such an array of artefacts untouched for so long is a rare and special occurrence. Equally rare is the presence of complete or semi-complete individual animals. We look forward to reaching the stage where the discoveries can be shared and displayed, so that everyone can find out more about our distant past.' The mutations that are different in these 4 sequences have been numbered and bolded. These mutations can then be used to build a phylogenetic tree for the four canids. In this example, the dog and grey wolf differ by two substitutions (highlighted in red), and each of them differs from the coyote by four substitutions. [94] Rob Bourn, the managing director of Orion Heritage and lead archaeologist on the project for the Sherford Consortium, said: “This is a major discovery of national significance, a once in a lifetime experience for those involved. To find such an array of artefacts untouched for so long is a rare and special occurrence.” The bones of mammoths, woolly rhinoceros and hyena are among the remains discovered in a cave during the construction of new houses in Sherford, near Plymouth. They date to the middle of the last Ice Age between 60,000 and 30,000 years ago.

References

a b c d e f g h Lescureux, Nicolas; Linnell, John D. C. (2014). "Warring brothers: The complex interactions between wolves ( Canis lupus) and dogs ( Canis familiaris) in a conservation context". Biological Conservation. 171: 232–245. doi: 10.1016/j.biocon.2014.01.032. Woodford, Riley (November 2004). "Alaska's Salmon-Eating Wolves". Wildlifenews.alaska.gov . Retrieved July 25, 2019. In 1986, a study of skull morphology found that the domestic dog is morphologically distinct from all other canids except the wolf-like canids. "The difference in size and proportion between some breeds are as great as those between any wild genera, but all dogs are clearly members of the same species." [81] In 2010, a study of dog skull shape compared to extant carnivorans proposed that "The greatest shape distances between dog breeds clearly surpass the maximum divergence between species in the Carnivora. Moreover, domestic dogs occupy a range of novel shapes outside the domain of wild carnivorans." [82] Comparison with modern wolves [ edit ]

Molnar, B.; Fattebert, J.; Palme, R.; Ciucci, P.; Betschart, B.; Smith, D. W.; Diehl, P. (2015). "Environmental and intrinsic correlates of stress in free-ranging wolves". PLOS ONE. 10 (9). e0137378. Bibcode: 2015PLoSO..1037378M. doi: 10.1371/journal.pone.0137378. PMC 4580640. PMID 26398784.

What is an Ice Age?

a b Kopaliani, N.; Shakarashvili, M.; Gurielidze, Z.; Qurkhuli, T.; Tarkhnishvili, D. (2014). "Gene Flow between Wolf and Shepherd Dog Populations in Georgia (Caucasus)". Journal of Heredity. 105 (3): 345–53. doi: 10.1093/jhered/esu014. PMID 24622972. Creel, S.; Fox, J. E.; Hardy, A.; Sands, J.; Garrott, B.; Peterson, R. O. (2002). "Snowmobile activity and glucocorticoid stress responses in wolves and elk". Conservation Biology. 16 (3): 809–814. doi: 10.1046/j.1523-1739.2002.00554.x. S2CID 84878446.

a b Sinding, Mikkel-Holger S.; Gopalakrishan, Shyam; Vieira, Filipe G.; Samaniego Castruita, Jose A.; Raundrup, Katrine; Heide Jørgensen, Mads Peter; Meldgaard, Morten; Petersen, Bent; Sicheritz-Ponten, Thomas; Mikkelsen, Johan Brus; Marquard-Petersen, Ulf; Dietz, Rune; Sonne, Christian; Dalén, Love; Bachmann, Lutz; Wiig, Øystein; Hansen, Anders J.; Gilbert, M. Thomas P. (2018). "Population genomics of grey wolves and wolf-like canids in North America". PLOS Genetics. 14 (11): e1007745. doi: 10.1371/journal.pgen.1007745. PMC 6231604. PMID 30419012.

Further information: Evolution of Canis and Canid relationships Canis etruscus skull in the Montevarchi Paleontological Museum