Many hystricognaths live in South, Central and North America, e.g. capybara, cavy or guinea-pig, coypu and the New World Porcupines; they generally have large heads, plump bodies, slender legs and short tails. The sub-order also includes the Old World porcupines belonging to the family Hystricidae, which gives the group their subordinal name, and such diverse creatures as chinchillas, gerbils and the African Mole Rat. Many are large rodents and used for food - capybara and guinea-pigs in South America; cane-rats and porcupines in Africa.

Skulls and dentition

Hystricognath skulls are rather angular with very strongly developed incisors. The surfaces of the cheek teeth show enormous variation in pattern and complexity among different species. The gnawing action is provided by the deep masseter muscle which extends forward through an opening in the zygomatic arch and attaches to the muzzle. The other end attaches to a characteristic outward projecting flange of the lower jaw. The lateral muscle is only used to close the jaw.