a genus of tridactylous fossil horse; existed from the Upper Miocene until the end of the Pliocene. Hipparion was a small horse (height, up to 1.5 m at the withers). The molars were shorter than in horses of the genus Equus, and the side toes (second and fourth) were small and could not spread outward to prevent the limbs from sinking into the ground. Hipparion lived in large herds (up to several thousand) on grassy, savanna-like plains with occasional groves and bodies of water. During the Upper Miocene they were distributed throughout North America, which is the first place they appeared; later they settled all the continents except South America and Australia.
More than 50 species of Hipparion are known; they all became extinct and left no descendants. Hipparion was replaced by the single-hoofed horse, which arose from the closely related genus Pliohippus. Better adapted to the conditions of life in the plains, Pliohippus moved from North America to all continents.
B. A. TROFIMOV