The Anchitheriinae are an extinct subfamily of the Perissodactyla family Equidae

Equidae

Equidae is the taxonomic family of horses and related animals, including the extant horses, donkeys, and zebras, and many other species known only from fossils. All extant species are in the genus Equus...

, the same family which includes modern horses, zebras and donkeys. This subfamily is more primitive then the living members of the family. The group first appeared with Mesohippus

Mesohippus

Mesohippus is an extinct genus of early horse. It lived some 40 to 30 million years ago from the late Eocene to the mid-Oligocene...

in north America during the middle Eocene

Eocene

The Eocene Epoch, lasting from about 56 to 34 million years ago , is a major division of the geologic timescale and the second epoch of the Paleogene Period in the Cenozoic Era. The Eocene spans the time from the end of the Palaeocene Epoch to the beginning of the Oligocene Epoch. The start of the...

 and thrived until the late Miocene

Miocene

The Miocene is a geological epoch of the Neogene Period and extends from about . The Miocene was named by Sir Charles Lyell. Its name comes from the Greek words and and means "less recent" because it has 18% fewer modern sea invertebrates than the Pliocene. The Miocene follows the Oligocene...

. The subfamily continued in Eurasia with the genus Sinohippus until the early Pliocene

Pliocene

The Pliocene Epoch is the period in the geologic timescale that extends from 5.332 million to 2.588 million years before present. It is the second and youngest epoch of the Neogene Period in the Cenozoic Era. The Pliocene follows the Miocene Epoch and is followed by the Pleistocene Epoch...

, when it finally went extinct.