Equus (genus) and pioneer spirit of the West" under the Wild and Free-Roaming Horses and Burros Act of 1971, and in "Kleppe v. New Mexico", the United States Supreme Court ruled that the animals so designated were, as a matter of law, wildlife. Equus (genus) Equus is a genus of mammals in the family Equidae, which includes horses, donkeys, and zebras. Within Equidae, "Equus" is the only recognized extant genus, comprising seven living species. The term equine refers to any member of this genus, including horses. Like Equidae more broadly, "Equus" has numerous extinct species known only from fossils. The genus most
Equus (genus) each other both visually and vocally. Human activities have threatened wild equine populations. The word "equus" is Latin for "horse", and is cognate with the Greek ἵππος ("hippos"), "horse", and Mycenaean Greek "i-qo" /ikkʷos/, the earliest attested variant of the Greek word, written in Linear B syllabic script.; compare the alternative development of the Proto-Greek labiovelar in Ionic ἴκκος ("ikkos"). The genus "Equus" was first described by Carl Linnaeus in 1758. It is the only recognized extant genus in the family Equidae. The first equids were small, dog-sized mammals (e.g. "Eohippus") adapted for browsing on shrubs during the Eocene, around