Chacoan mara the capybara, and guinea pigs. Chacoan maras are closely related to the other member of the genus "Dolichotis", the Patagonian mara. Maras are the fourth largest rodent in the world after the capybaras, beavers and porcupines . Though the mara may look like a rabbit, the rabbit is not actually a rodent and therefore not as closely related to the mara as one might expect. Chacoan mara The Chacoan mara, Dolichotis salinicola, is a relatively large South American rodent of the cavy family. They are a close relative of the better known Patagonian mara. The Chacoan mara lives in the
Guinea pig for researching scurvy. From the accidental discovery in 1907 that scurvy could be induced in guinea pigs, to their use to prove the chemical structure of the "ascorbutic factor" in 1932, the guinea pig model proved a crucial part of vitamin C research. Complement, an important component for serology, was first isolated from the blood of the guinea pig. Guinea pigs have an unusual insulin mutation, and are a suitable species for the generation of anti-insulin antibodies. Present at a level 10 times that found in other mammals, the insulin in guinea pigs may be important in growth regulation, a