Microcavia (mountain cavies) is a genus of rodents in the family Caviidae. They are unique within their family in that their premolar teeth do not grow and replace the original deciduous cheek teeth until after the animal is born; in other genera this occurs in the womb. It contains three extant species: \n* Southern mountain cavy, M. australis \n* Andean mountain cavy, M. niata \n* Shipton's mountain cavy, M. shiptoni At least nine fossil species have also been named, dating back to the mid Pliocene, although it is unclear how many of these are truly valid.