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EquidaeExtant Ypresian first appearancesMammal familiesTaxa named by John Edward Gray

Equidae

Adapted from Wikipedia · Discoverer experience

A Persian onager, a wild relative of domestic donkeys, at Dubbo Zoo.

The Equidae family, also called the horse family, includes animals like horses, asses, zebras, and many ancient species known only from fossils. These animals first appeared over 50 million years ago during a time called the Eocene epoch. They evolved from small creatures with many toes into the large, single-toed animals we know today.

All living members of this family belong to the group called the genus Equus, which began in North America. Equidae is part of a larger group of animals named Perissodactyla, which also includes animals such as tapirs and rhinoceros. Within this group, Equidae is part of a subgroup called Equoidea, which only has one other ancient family known as Palaeotheriidae.

The word equid is used to describe any animal in this family, including any type of equine. These animals have played important roles in human history, helping with transportation, work, and even as friends.

Evolution

Main article: Evolution of the horse

Extinct equids restored to scale. Left to right: Mesohippus, Neohipparion, Eohippus, Equus scotti and Hypohippus

The oldest known fossils of the horse family, Equidae, were found in North America and date back to the early Eocene epoch, about 54 million years ago. These early animals were small, about the size of a fox, and had several toes on each foot. They ate soft plants and were already built for running. Over time, their bodies changed, losing some toes and developing teeth better suited for eating tough grasses.

During the Miocene epoch, the horse family grew more diverse, with many new species appearing. By this time, they looked more like modern horses, with a body shape we recognize today. The genus Equus, which includes all living horses, asses, and zebras, evolved by the early Pleistocene epoch and spread worldwide.

Classification

Skeletons

The Equidae family includes horses, asses, zebras, and many extinct species known only from fossils. This family belongs to the order Perissodactyla, which also includes tapirs and rhinoceroses.

The Equidae family has several subfamilies and genera, many of which are now extinct. The subfamily Equinae includes the modern genus Equus, which contains 22 species, including the familiar horse and zebra.

Images

An artist’s reconstruction of Hipparion, an ancient three-toed horse that lived millions of years ago.
A Przewalski's horse, a rare wild horse species known for its distinctive markings.
Scientific illustration of Palaeotherium medium, an extinct mammal, based on fossil skull and limb studies.
An artist’s reconstruction of Hyopsodus, a small early mammal from the Eocene period of North America, showing what scientists believe it looked like millions of years ago.
An artistic reconstruction of Meniscotherium, an ancient mammal that lived millions of years ago in North America.
Artist's reconstruction of Heptodon posticus, an ancient mammal.
Illustration of a giant tapir from ancient times in South China.
An artist’s reconstruction of Paraceratherium, an enormous ancient mammal from the fossil record.
An artist’s reconstruction of a Woolly Rhinoceros, an ancient ice-age mammal that lived in Europe and Asia.
An artist's reconstruction of Elasmotherium caucasicum, a large, ancient hoofed mammal from the Pleistocene epoch.
An artist’s illustration of Hyracodon, an ancient prehistoric mammal.

This article is a child-friendly adaptation of the Wikipedia article on Equidae, available under CC BY-SA 4.0.

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