1) Equus caballus 2) Horse 3) Transitional fossil 
Mesohippus (Greek: μεσο/meso meaning `middle` and ιππος/hippos meaning `horse`) is an extinct genus of early horse. It lived some 30 to 40 million years ago from the Middle Eocene to the Early Oligocene. Like many fossil horses, Mesohippus was common in North America. Mesohippus had longer legs than its predecessor Eohippus and stood ...
• (n.) An extinct mammal of the Horse family, but not larger than a sheep, and having three toes on each foot.
genus of extinct early and middle Oligocene horses (the Oligocene Epoch occurred from 36.6 to 23.7 million years ago) commonly found as fossils in ... [2 related articles]
Mesohippus meaning middle horse) is an extinct, dog-sized, three-toed horse. It was about 4 feet (1.2 m) long and was roughly 2 feet (60 cm) tall at the shoulder. Its middle toe had a light-weight hoof wth a large, weight-supporting middle toe; the head was long and pointed (the jaws were shallow). Mesohippus lived during the middle Oligocene (abou...
Mes`o·hip'pus noun [ New Latin , from Greek 
[n] - North American 3-toed Oligocene animal
noun North American three-toed Oligocene animal; probably not directly ancestral to modern horses