The rhinoceros is the horned, armor-plated mammal often called a living dinosaur.
Rhinoceroses are large odd-toed ungulates in the family Rhinocerotidae. Five living species survive: the white, black, Indian, Javan, and Sumatran rhinoceroses. Depending on the species, the nose carries one or two horns made of keratin, the same structural protein found in human hair and fingernails.
Rhinoceroses are mammals, not reptiles or dinosaurs, despite their ancient-looking appearance. The Indian rhinoceros has prominent skin folds that resemble armor, while the white rhinoceros is especially known for its broad, grazing-friendly mouth. Their closest living relatives include horses and tapirs, rather than elephants or hippopotamuses. Several rhinoceros species are threatened by habitat loss and poaching for their horns.