That means that the closest living relatives of the modern horse are fellow perissodactyls, rhinoceroses and tapirs.

Interesting fact: When the film director Stanley Kubrick recreated scenes of human ancestors in the first part of his movie "2001," he used living tapirs to simulate the archaic beasts that lived at the same time. It was good casting, because tapirs have retained a lot of the primitive features of early perissodactyls.