A new study on the topic looks at Equus ferus, an extinct species that sired both domestic horses (Equus ferus caballus) and the wild Przewalski's horses (Equus ferus przewalskii) pictured above. Researchers t

The horse (Equus ferus caballus)[2][3] is one of two extant subspecies of Equus ferus, or the wild horse. It is a single-hooved (ungulate) mammal belonging to the taxonomic family Equidae. The horse has evolved over the past 45 to 55