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A brief history of the horse in America
Horse phylogeny and evolution
Story by Ben Singer

natural history Modern Horses (Equus caballus) belong to the Perissodactyls, an order that includes tapirs and rhinos. They are “odd-toed” hoofed mammals that walk on modified third toes. The family Equidae (Equids) includes modern horses, zebras, asses and many extinct cousins.

The ancestor of all equids, Eohippus (aka Hyracotherium), lived in the early Eocene epoch: 54 - 55 million years ago

  • It was a small, fox-like animal with four toes
  • Hyracotherium lived on grasslands in both North America and Europe
  • It was thought to have evolved on both continents, but the descendents were more successful in North America
Horse evolution continued through series of genera in N. America, throughout the Eocene epoch:
  • 50 - 47 million years ago (mya): Orohippus
  • 47 - 40 mya: Epihippus
  • 40 - 30 mya: Mesohippus: had developed narrow skull, characteristic of horses
  • 37 - 25 mya: Miohippus

Eocene horse variants crossed into Eurasia over land bridges at different times, but weren’t able to become as well-established as their cousins in the New World.

By 25 mya, not much branching had taken place took place, but from then onwards the line branched into two major groups in the Oligocene epoch:

  • Anchitherinae, which went extinct by 7 mya in Asia and North America
  • Equinae, which developed a densely packed foot good for running in open grasslands
The Equinae gave rise to several intermediate species in the middle Miocene (15 mya).
  • Kalobatippus
  • Archaeohippus
  • Parahippus


Learn more:
•  Sable Island

•  Spanish blood

•  Spanish mustang trail
Each new variant had better developed molars for eating tough grasses. From later parahippus species, molars and premolars had high crowns with cementum, ideal for chomping silica-covered grass.

In middle Miocene (15 mya) horse ancestry split into three branches or “tribes” that are complicated in the fossil record by parallel evolution:

  • Protohippini
  • Hipparionini - had three-toes for marshy terrain, lived in North America until 5 mya, and Africa until Africa until 1 mya
  • Equini, which reduced it’s toes to one on each foot

Some early horse variants occurred as far north as the Yukon in Canada, 1.2 mya.

Equini branched several times in North America:

  • Pliohippus lived in N. America from 14.5 — 6 MYA (Pliocene) during a time of expanding plains and grasses and rapid branching and evolution of horse-species
  • Pliohippus gradually gave rise to Dinohippus, which lived in N. America 8 — 5 MYA, which gave rise to Equus which is the modern horse genus.
  • In the Early Pleistocene (3 mya) horses spread to Eurasia over the Bering land bridge, displacing earlier Hipparion ancestors there and gave rise to modern horses in the north and zebras and asses in hotter climes


North American horses disappeared around 8,000 - 10,000 years ago. Multiple factors including hunting by early Natives, climate change, and disease are thought to have helped contribute to their demise. They disappeared around the same time as other large mammals like Wooly Mammoths.

Human contact with horses is thought to have first occurred around 3 mya, as Homo sapiens moved out of Africa. Ancient Eurasians were known to hunt and eat horses, and their meat formed a staple of many diets at the time.

First domestication of horses occurred around 3,000 B.C. in the Middle East. At this time, the horse replaced the onager as a beast of burden. In fact, European horses were domesticated for several thousand years at the time the Spanish began exploring the Americas in the late 15th century.

Spain’s king gave Conquistadors very fine horses, which the sailors sold to buy cheaper, hardier horses — Iberian Barb’ descendents, also known as Jennets or Andaluz Mustangs. These creatures were small and rugged working, unique to Iberia. They no longer exists but their legacy lives on as Iberian horses have a rich history in horsemanship and breeding. Likewise, old Spanish horses not around anymore outside of heritage in some wild/domestics.

The first Spanish horses arrived in the Carribbean in the early 1500s. In 1519, Conquistadors re-introduced horses to North America. Fifteen horses were brought by the Cortez expedition and were imported by Spanish homesteaders to Mexico and New Mexico. The re-introduced species made their way north through the western U.S. west of the Rocky Mountains to the coast, following the expansion of the Mexican/Spanish. Although greatly valued by their owners, they occasionally escaped, fueling Navajo raiders as early as 1606. Trading and warring among Natives resulted in a rapid spread pf horses through the continent.

Within 150 years of the first colonizers, herds of millions ÿ mostly Spanish Andaluz Mustangs — were roaming the plains. The following centuries saw other European settlers bringing their own horses from the east. British and French colonizers introduced Thoroughbreds, where as Russians are thought to have brought horses to the continent from the Northwest, but this is unestablished. Most non-Spanish stock blended together, becaming "North American breeds" through cross-breeding. In the 1800s in the U.S., millions of horses were collected for riding and other use by ranchers and the military. By the late 1800s millions of wild horses were killed due to increasing land conflicts with ranchers.

Today, there are hundreds of wild horse herds in North America. Their numbers are estimated to be about 15,000 in total where as once vast herds of millions roamed western North America. Even though horses produce just one foal per year, herds can expand 17 percent per year.

Today the vast majority of wild horses are in Nevada with a fair number spreading throughout the west in Wyoming, Colorado and Oregon — states where there is a lot of public land. Another herd of note are those on the Barrier Islands off the coast of North Carolina.

In Western Canada, settlement occurred later so horse populations once numbered in the millions. Also, there is clear evidence of horses until 12,000 years ago with isolated finds indicating there may have been horses closer to 3000-1000 years ago.

Anecdotal evidence shows that in 1776, herds of mustangs were kept by Assiniboines in Manitoba and Saskatchewan. By 1790, Alberta tribes had acquired mustangs from Shoshoni and under two decades later, there were extensive herds in the Kootenays, estimated at two million in total! Wild herds served as stock for Natives, and escapees often replenished them.

There are four main herds of horses in Canada today: Sable Island in Nova Scotia, two herds in B.C.’s Brittany Triangle (Chilcotin), and one in the Siffleur Wilderness Area in Alberta. Herds in both B.C. and Alberta have shown evidence of Spanish blood, possibly from the “Spanish mustang trail” that came from Mexico up to the Canadian prairies.


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