Przewalski's Horse (Equus ferus przewalskii) Fact Sheet: Taxonomy & History

Taxonomy

• Horses were previously assigned to 2 different species, Equus caballus and E. przewalskii.
  •  In 1986 and 1994 Colin Groves, a leading taxonomist, proposed using E. caballus for all domestic horses and E. ferus for the 2 wild horses: 
    • E. ferus przewalskii = Przewalski horse
    • E. ferus ferus = tarpan (extinct in the wild around 1897)
• Equus ferus przewalskii and E. caballus able to interbreed (e.g., Der Sarkissian et al. 2015; Gashchak and Paskevych 2019)

Nomenclature

• Named for 19th century Russian explorer, Col. Nikolai Przewalski (pronounced zheh-VAHL-skee)
  • Przewalski shipped a skull and skin to the St. Petersburg Zoological Museum
    • I.S. Poliakov, museum conservator, declared the horse a new species, Equus przewalskii
• Common Names
  • Przewalski’s wild horse
  • Asiatic wild horse
  • Mongolian wild horse
  • Mongolian takh
  • Takhi (spirit horse)

Horses

• Horses diverged from rhinos between 54 and 58 million years ago (early Eocene) (Ryder 2009)
  • Horse lineages are called the hippomorphs; tapirs and rhinos are the ceratomorphs
• Horses likely first dispersed from Europe to North America at the beginning of the Eocene (Hooker 2008)
  • Pliolophus is now considered the earliest horse; it is closely related Hyracotherium from North America (Froehlich 2002; Hooker 2008)
  • Pliolophus had four hooves on front limbs, three on rear, with short legs and was half the size of a fox terrier (Agusti & Anton 2005; Hooker 2008)
• Horse family, Equidae, has three main divisions based on anatomy and DNA studies (Oakenfull et al 2000)
  • Horses: domestic and wild horses (Forstén 1988)
    • Includes Przewalski's horse
  • Asses
    • Domestic donkey
    • African wild asses
    • Asiatic onager
    • Kiang
  • Zebras
• The genus Equus likely originated 4.0-4.5 million years ago (Orlando et al. 2013)
• Equus dispersed from North America to Eurasia around 2.6 million years ago (Steiner & Ryder 2011)
• The modern horse genus Equus probably evolved in North America and migrated across the Bering land bridge into Asia and Europe (Steiner & Ryder 2011)
• ~150,000 years ago
  • Divergence of Late Pleistocene horse, domestic horse, and Przewalski's horse lineages (Der Sarkissian et al. 2015)

Przewalski's horse

• Przewalski's horses are closely related to but not direct ancestors of modern domestic horses (Goto et al. 2011; Lau 2009; Orlando et al. 2013; Vilà et al. 2001)
  • 45,000 years ago: diverged of Przewalski's horses and modern domestic horses (Orlando et al. 2013; Der Sarkissian et al. 2015)
  • Przewalski's and domestic horses have unique evolutionary histories (Lau 2009)
  • Przewalski's horses are only surviving wild horse (Orlando et al. 2013)
    • DNA evidence shows no recent admixture with domestic horses

• 30,000 years ago
  • Wild horses hunted as prey by early humans
• 20,000 years ago
  • Rock art engravings/paintings of wild horses in Italy, France and Spain
• 10,000 years ago
  • Massive extinctions in North and South America wiped out all horse species, mammoths, and saber-tooth tigers
    • In Eurasia and Africa, 7 equid species survived
• 3,000 B.C.
  • Domestication began
    • Tamer horses kept for breeding
    • Horses not tamed killed for food
• 900 A.D.
  • First account of wild horse written by a Tibetan monk
• 1226 A.D.
  • Seen by Genghis Khan during one of his Mongolian campaigns
• 1750
  • Manchurian emperor shot 200 to 300 wild horses in a single day
• 1881
  • Skull and hide shipped to St. Petersburg Zoological Museum
    • Przewalski’s horse became known to western societies
• After WWII
  • Dramatic declines due to hunting, military activities, climate change, livestock competition, and numerous collecting expeditions
• 1969
  • Last confirmed sighting in southwestern part of Mongolia
• See additional records in Kaczensky et al. (2017); Table 1

Kingdom: Animalia

Phylum: Chordata

Class: Mammalia

Order: Perissodactyla

Family: Equidae — horses, asses, zebras

Genus: Equus — horses

Species: Equus ferus — wild horse, Eurasian wild horse

Subspecies: Equus ferus przewalkskii — Przewalski's horse

Describers
Equus caballus, Linnaeus (1758); Syst. Nat., 10th ed., 1:73
Equus ferus, Boddaert (1785)
Equus przewalskii, Polyakov (1881)
Equus ferus przewalskii, Groves (1986)

The Przewalski's horses is the only surviving wild horse.

Przewalski's and domestic horses are evolutionarily distinct. Their lineages diverged approximately 150,000 years ago.

Image credit: © San Diego Zoo Wildlife Alliance. All rights reserved.

Agusti & Anton (2005)
Bennett & Hoffmann (1999)
Bowling & Ruvinsky (2000)
Boyd (1994)
Forstén (1988)
Froehlich (2002)
Groves (2002)
Groves & Ryder (2000)
Hooker (2008)
Oakenfull et al. (2000)
Ryder (2009)
Steiner & Ryder 2011)
Villa et al. (2001)
Wilson & Reeder (2005)