Mara

The maras (Dolichotis) are a genus of the cavy family. They are the sole representatives of the subfamily Dolichotinae. These large relatives of guinea pigs are common in the Patagonian steppes of Argentina but live in other areas of South America as well such as Paraguay. Maras are the fourth largest rodent in the world, after capybaras, beavers, and porcupines, reaching about 45 cm (18 in) in height.

http://en.wikipedia.org/wiki/Dolichotis