Rhinoceroses are some of the largest remaining megafauna: all weigh at least one tonne in adulthood. They have a herbivorous diet, small brains (400–600 g) for mammals of their size, one or two horns, and a thick (1.5–5 cm), protective skin formed from layers of collagen positioned in a lattice structure. They generally eat leafy material, although their ability to ferment food in their hindgut allows them to subsist on more fibrous plant matter when necessary. Unlike other perissodactyls, the two African species of rhinoceros lack teeth at the front of their mouths; they rely instead on their lips to pluck food.
Rhinoceros are killed by some poachers for their horns, which are bought and sold on the black market, and used by people in some cultures for ornaments or traditional medicine. Although rapidly declining in many regions, East Asia as well as a few other regions were seen as the largest market for rhino horns. It was seen as a medicine in ancient China (TCM), a belief that was spread widely across to other Asian countries. By weight, rhino horns cost as much as gold on the black market, making it novel for criminal and illegal poachers. However, the horns are made of keratin, the same type of protein that makes up hair and fingernails, which have null medicinal properties, despite TCM texts saying that rhino horns were "detoxifiers". Rhino horn consumption was also related to status and wealth, with the majority of consumers being older, educated, wealthy men, or those seeking rhino horn ornaments. Demand was driven from sudden wealth, and medicinal misinformation.
