Class: Mammalia (mammals) (Linnaeus, 1758)
Order: Artiodactyla* (or Cetartiodactyla) (even-toed hoofed animals: includes pigs, sheep goats, cattle, deer) (Owen 1848)
Family: Bovidae (buffalo, cattle, sheep, goats) (Gray, 1821)
Subfamily: Caprinae (goats, sheep) (Gray, 1821)
Genus: Ovis (sheep, mouflons, urial, argali, bighorn, thin horns snow sheep, Dall's sheep) (Linnaeus, 1758)
Species: Ovis canadensis (Shaw, 1804) - bighorn sheep
Subspecies: O. c. auduboni (Merriam, 1901)
Subspecies: O. c. californiana (Douglas, 1829) - California bighorn sheep
Subspecies: O. c. canadensis (Shaw, 1804) - Rocky Mountain bighorn sheep
*Subspecies: O. c. cremnobates (Elliot, 1904) - Peninsular bighorn sheep
Subspecies: O. c. mexicana (Merriam, 1901) - desert bighorn sheep
*Subspecies: O. c. nelsoni (Merriam, 1897) - Nelson's/Nelson bighorn sheep, Peninsular bighorn sheep, desert bighorn sheep
Subspecies: O. c. weemsi (Goldman, 1937)
*Wehausen and Ramey (1993) synonymized O. c. crenobates and O. c. nelsoni.
Describer: Shaw (1804). The Canadian Sheep. Plate 610, the description and the index in The Naturalist’s Miscellany (by G. Shaw and E. Nodder), Vol 15. Nodder and Co., London.
**New anatomical and DNA evidence on the relationship between Artiodactyla (even-toed ungulates) and Cetacea (whales and dolphins) recently led to a merging of the two orders into a new group, Cetartiodactyla (Montgelard, 1997; reviewed in Kulemzina, 2009). As of October 2012, experts had not agreed on whether to define Cetartiodactyla as an official taxonomic order that would replace Artiodactyla and Cetacea. Some continue to list okapi in the order Artiodactyla (Franklin, 2011) or use the term Cetartiodactyla without defining it as an order (IUCN, 2008).
Young & Manville (1960)
Ramey & Wehausen (1993)
Boyce et al. (1999)