Horses as we know them were brought to America by Christopher Columbus, who discovered the New World in 1492. But horses weren’t new to America even then. We now know that the first real horse, called Eohippus, emerged here about 60 million years ago, just after the dinosaurs died out — long before any people came along. Eohippus first appeared in what is called the Eocene period, the dawn of the Age of Mammals. Mammals are those animals that have hair and nurse their young, like horses, deer, whales, and people.
The name Eohippus (pronounced Ee-oh-hip-us) means “dawn horse” in Latin, a language scientists use for describing things. Unlike our horses, Eohippus was small, about the size of a cat or small dog. At 10 to 20 inches tall, a little Eohippus would have fit nicely in a grown-up’s lap. The largest Eohippus was only half the size of a small Shetland pony.
Eohippus was different from our horses in other ways, too. It had very long back legs, making it look more like a rabbit than a horse, and a long, bony tail — the long tails of modern horses are mostly made of hair. Eohippus backbones were flexible and arched, while our horses have straight, rigid backbones. The most unusual thing about Eohippus was that it had four small hooves on each of its front feet and three hooves each on its back feet. Modern horses have only one large hoof on each foot.
It took decades for scientists to realize that Eohippus was a horse at all. Since this animal lived long before anyone was ever born and is now extinct, all we know about it comes from fossils — bones that were buried long ago and have since been turned to stone. The first, partial Eohippus fossils were found in the mid-1800s, in the western United States and England, where Eohippus goes by the tongue-twisting title Hyracotherium (Hi-rack-oh-the-ree-um). It took quite a while for scientists to find a complete Eohippus skeleton so that they could know what all of the creature looked like. Now, there’s no doubt that Eohippus was the first horse. Studies of Eohippus skeletons have proved that their bones are very like those of horses today.
Scientists can tell a lot about an animal just by looking at its bones. For example, we know that there were many types or species of Eohippus; today there are only one or two species of horses, although a few horse relatives like zebras and donkeys are still around. The long, strong leg bones of Eohippus tell us that the first horses were already very fast little animals. Like modern horses, they could probably run as fast as 35 miles per hour. Their teeth are also very important. Eohippus had sharp, flat teeth (incisors) in the front of its mouth that it used to snip off and grasp food. In back it had a row of crushing and grinding teeth called molars. The shape of the lower jaw tells us that, like our horses, it moved its food around with its tongue. The types and shapes of its teeth let us know that (unlike some of its ancestors) it ate only plants. The teeth weren’t very useful for grinding up grass, the way today’s horses do, so we think it must have eaten only leaves and soft fruits and seeds. An animal that eats this type of food is called a “browser”; an animal that eats grass is called a “grazer”. Eohippus must have lived in forests, where it was easy to find leaves and fruits.
We know that some species of Eohippus still existed until about 38 million years ago; but no Eohippus fossils younger than that have been found. What happened to Eohippus? No one knows for sure, but scientists think that the different types of Eohippus slowly began to change into many types of bigger horses, some with three hooves on each foot and some with only one hoof per foot. These animals were able to spread over most of the world because sometimes, when the oceans are low, America and Europe are connected by narrow strips of ground called land bridges. Over many years, all the horses except the ones with one hoof on each foot died out, leaving us with modern horses, zebras, donkeys, and their relatives.
In America, horses became extinct about 11,000 years ago. Scientists now believe this was just after the very first people came to America. These first Native Americans may have killed all the horses, possibly for food, in a span of less than 1,000 years. So, sadly, the birthplace of all horses was empty of them until Christopher Columbus arrived just 500 years ago.
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