Equus occidentalis Leidy, 1865:94

Western horse



Taxonomy & Nomenclature

Considered a synonym of E. mexicanus by (Alberdi et al. 2014).


Conservation Status


Last record: Late Pleistocene





Biology & Ecology










Original scientific description:

Leidy, J. (1865). Bones and teeth of horses from California and Oregon. Proceedings of the Academy of Natural Sciences of Philadelphia 1865: 94.


Other references:

Alberdi, María Teresa, Arroyo-Cabrales, Joaquín, Marín-Leyva, Alejandro H. and Polaco, Oscar J. (2014). Study of Cedral Horses and their place in the Mexican Quaternary. Revista Mexicana de Ciencias Geológicas 31(2): 221-237.

Annoor, Tahsin et al. (2018). From colts to horses: a study of the allometric growth in the limb bones in Equus occidentalis from the La Brea Tar Pits, pp. 13-16. In: Lucas, Spences G. and Sullivan, Robert M. (eds). Fossil Record 6(1). New Mexico Museum of Natural History & Science Bulletin 79.

Azzaroli, A. (1998). The genus Equus in North America: The Pleistocene species = Le genre Equus en Amérique du Nord - Les espèces du Pléistocène. Palaeontographia Italica 85: 1-60. [Abstract]

Bennett, D. K. 1980. Stripes do not make a zebra, part I: A cladistic analysis of Equus. Systematic Zoology 29(3): 272-287.

Brown, Kristen E., Akersten, William A. and Scott, Eric. (2015). Equus occidentalis Leidy from “Asphalto,” Kern County, California, pp. 81-89. In: Harris, John M. (ed.). La Brea and Beyond: The Paleontology of Asphalt-Preserved Biotas. Los Angeles, California: Natural History Museum of Los Angeles County, Science Series No. 42. 174 pp.

Cirilli, Omar, Machado, H., Arroyo-Cabrales, J., Barrón-Ortiz, C. I., Davis, E., Jass, C. N., Jukar, A. M., Landry, Z., Marín-Leyva, A. H., Pandolfi, L., Pushkina, D., Rook, L., Saarinen, J., Scott, E., Semprebon, G., Strani, F., Villavicencio, N. A., Kaya, F. and Bernor, R. L. (2022). Evolution of the Family Equidae, Subfamily Equinae, in North, Central and South America, Eurasia and Africa during the Plio-Pleistocene. Biology 11(9): 1258.

Cohen, Joshua E. et al. (In press, 2021). Dietary stability inferred from dental mesowear analysis in large ungulates from Rancho La Brea and opportunistic feeding during the late Pleistocene. Palaeogeography, Palaeoclimatology, Palaeoecology. doi: [Abstract]

Colbert, E. H. 1950. The fossil vertebrates. Pp. 126-148 in The stratigraphy and archaeology of Ventana Cave. University of Arizona Press and University of New Mexico Press, Tucson and Albuquerque.

Cope, E.D. 1884. The extinct Mammalia of the Valley of Mexico. Proceedings of the American Philosophical Society 22(117): 1-21.

Dalquest, W.W. 1978. Phylogeny of American horses of Blancan and Pleistocene age. Annales Zoologici Fennici 15(3): 191-199.

Gidley, J.W. 1901. Tooth characters and revision of the North American species of the genus Equus. Bulletin of the American Museum of Natural History 14: 91-142.

Harris, Arthur H. (1987). Reconstruction of Mid Wisconsin Environments in Southern New Mexico. National Geographic Research 3(2): 142-151.

Harris, A. H. 1989. The New Mexican late Wisconsin—east versus west. National Geographic Research 5:205-217.

Harris, A. H. 1993. Quaternary vertebrates of New Mexico. Pp. 179-197, in Vertebrate Paleontology in New Mexico, New Mexico Museum of Natural History, Bulletin 2:i-vii, 1-338.

Harris, Arthur H. and Porter, Linda S. W. (1980). Late Pleistocene horses of Dry Cave, Eddy County, New Mexico. Journal of Mammalogy 61(1): 46-65.

Hibben, F. C. 1941. Evidences of early occupation in Sandia Cave, New Mexico, and other sites in the Sandia-Manzano region. With appendix on Correlation of the deposits of Sandia Cave, New Mexico, with the glacial chronology. Smithsonian Miscellaneous Collections 99(23):i-vi, 1-(?63+)

Jefferson, G. T. 1991. A catalogue of Late Quaternary vertebrates from California. Part two: Mammals. Natural History Museum of Los Angeles County Technical Reports 7:1-129.

Jefferson, G. T., H. G. McDonald, and S. D. Livington. 2015. Catalogue of late Quaternary and Holocene fossil vertebrates from Nevada. Nevada State Museum, Occasional Papers no. 6a:iv + 86.

Jones,Davis Brent and Desantis, Larisa R. G. (In Press, 2016). Dietary ecology of ungulates from the La Brea tar pits in southern California: A multi-proxy approach. Palaeogeography, Palaeoclimatology, Palaeoecology. [Abstract]

Kottkamp, Scott et al. (2022). Pleistocene vertebrates from Carlsbad Caverns National Park, New Mexico. In: Morgan et al. (eds.). Late Cenozoic Vertebrate Paleontology: Tribute to Arthur H. Harris. New Mexico Museum of Natural History and Science Bulletin 88: 267-290.

Kurtén, B., and Anderson, E. (1980). Pleistocene mammals of North America. New York: Columbia University Press, xvii + 442 pp.

Leidy, J. (1869). 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 of the Academy of Natural Sciences of Philadelphia 7(2): 1-472.

Leidy, J. (1873). Contributions to the extinct vertebrate fauna of the Western Territories. Report of the U.S. Geological Survey of the Territories, F.V. Hayden, U.S. geologist in charge. Washington, D.C.: U.S. Government Printing Office, 358 pp, pls. i-xxxv.

MacFadden, B.J. 1998. Equidae. In Evolution of tertiary mammals of North America, ed. C.M. Janis, K.M. Scott, and L.L. Jacobs, vol. 1, 537–559. Cambridge, U.K.: Cambridge University Press.

May-Davis, Sharon et al. (2021). A comparative morphological study of the spinous processes of the sixth and seventh cervical vertebrae in extinct and extant species of Equus. Vertebrate Anatomy Morphology Palaeontology 9: 40-51.

Merriam, J. C. (1913). Preliminary report on the horses of Rancho La Brea. University of California Publications, Bulletin of the Department of Geological Sciences 7: 397-418.

Miller, W. E. (1971). Pleistocene vertebrates of the Los Angeles Basin and vicinity (exclusive of Rancho La Brea). Bulletin of the Los Angeles County Museum 10: 1-124.

O'Keefe, F. Robin et al. (2023). Pre–Younger Dryas megafaunal extirpation at Rancho La Brea linked to fire-driven state shift. Science 381(6659): eabo3594.

Savage, D. E. (1951). Late Cenozoic vertebrates of the San Francisco Bay Region. University of California Publications, Bulletin of the Department of Geological Sciences 28(10): 215-314.

Schultz, J. R. (1937). A Late Quaternary mammal fauna from the tar seeps of McKittrick, California. Ph.D. thesis, California Institute of Technology, 202 pp + 2 plates.

Scott, E. (2004). Pliocene and Pleistocene horses from Porcupine Cave. In Biodiversity response to environmental change in the Middle Pleistocene: The Porcupine Cave fauna from Colorado, ed. A.D. Barnosky, 264–279, Berkeley: University of California Press.

Springer, K., E. Scott, C. Sagebiel, and L. K. Murray. 2009. The Diamond Valley Lake local fauna: Late Pleistocene vertebrates from inland southern California. Pp. 217-235, in Papers on geology, vertebrate paleontology, and biostratigraphy in honor of Michael O. Woodburne (L. G. Albright, III, ed.). Museum of Northern Arizona Bulletin 65, Flagstaff, Arizona.

Stock, C., and Harris, J. M. (1992). Rancho La Brea: A record of Pleistocene life in California. Natural History Museum of Los Angeles County, Science Series no. 37, 7th ed.:i-xiv + 1-113.

Tomassini, R. L., Pesquero, M. D., Garrone, M. C., Marin-Monfort, M. D., Cerda, I. A., Prado, J. L., et al. (2021). First osteohistological and histotaphonomic approach of Equus occidentalis Leidy, 1865 (Mammalia, Equidae) from the late Pleistocene of Rancho La Brea (California, USA). PLoS ONE 16(12): e0261915.

Whitney, J. D. (1880). The auriferous gravels of the Sierra Nevada of California. Memoirs of the Museum of Comparative Zoology 6(1): 569.

Willoughby, D. P. 1974. The empire of Equus. A. S. Barnes and Company, South Brunswick, 475 pp. Early prehistoric agriculture in the American Southwest 1st ed.

Wilson, R. W. 1933. Pleistocene mammalian fauna from the Carpinteria asphalt. Carnegie Institute of Washington, Publication 440:60-76.

Winans, M. C. 1985. Revision of North American fossil species of the genus Equus (Mammalia:Perissodactyla:Equidae). Dissertation, University of Texas at Austin, 264 pp.


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