The Evolution of the Horse

Skeletal System

Horses Past to Present

Recent studies show that Paleozoontologists have been able to trace the modern horse's evolutionary lineage more than any other species. The evolution of the horse began with the small, dog-sized Eohippus. Horses also share a common ancestry with tapirs and rhinoceros. Horses are common domesticated animals, today, around the U.S and other countries around the world.(6) The natural habitats of the horse are grasslands, grassy fields, zoos or farms. Horses have adapted long legs giving them the ability to escape from their predators. Their short fur also keeps them unheated from hot climates during different seasons. Not all Horses have these traits, horses fall into 3 subcategories: spirited "hot bloods" with speed and endurance; "cold bloods", such as draft horses and some ponies, suitable for slow, heavy work; and "warm bloods”, horses with a medium muscle tone and height. (6) Predators of horses mainly include large felines and humans. Horses are classified as herbivores, meaning they eat hay or grass when available. (4)

55 million years ago was the first ancestor in mind for the horses called the Eohippus. The Eohippus had a short face and low-crowned teeth. Their molars represent the characteristics of a horse’s molar today. Later on, around 32-25million years ago the Miohippus gave rise and created the diversity in the horse family. The Miohippus ranged a bit larger than normal and at adult age it would weigh around 100 pounds. (5)Merychippus marked a significant change in the evolution of horses. Though it kept the character of 3 toes, it looked very much like a modern horse. Merychippus had a long face and long legs which allowed it to escape from predators and migrate long distances for its food. It had high-crowned cheek teeth and lived from 17-11 million years ago. These species are among many of the ancestors of horse species. Equus is the only surviving genus in the once diverse family of horses. It was domesticated about 3,000 years ago and has had a great impact on human history in areas such as migration, farming, warfare, sport, communication, and travel. Species of Equus lived from 5 million years ago until the present. (2)

Other species in the Horse clade are Orohippus, Epihippus, Mesohippus, Kalobatippus, Parahippus, Hipparion, Pliohippus, Dinohippus, and Plesippus. According to, fossils of the miohippus were found in different terrain in the Great Plains, the western US and a few places in Florida. (3) Evidence of evolution of the horse includes many features such as the morphology. Morphology is the study of the form and structure of organisms and description of its structures. The morphology of the horse includes mane, withers, back, loin, croup, flank, tail among others. A vestigial organ in today’s horses would be the plantaris muscle. Vestigial organs help scientists find evidence in evolution, in a way, because they might not be useful now, but they were once useful to their ancestors. Another clue to patterns of past evolution is found in the natural geographic distribution of related species. It is clear that major isolated land areas and island groups often evolved their own unique plant and animal communities. (7) Artificial selection on horses has been used earlier on in a profitable way such as horse racing. Trainers breed a strong horse and a really fast horse to get those desired traits in their offspring. (1) Lastly, but not least fossils play an important role when it comes to evolution. Fossils give evidence of ancestors of the organism and how they’ve evolved. Fossil record can be done by relative or radioactive dating. Fossils of these species have been found in many places throughout the world except for Australia and Antarctica. (2)


Evolution of the Horse

The Evolution of the horse.