The four species of chevrotain, also known as mouse deer, make up the family Tragulidae. Chevrotains are small, secretive creatures, now found only in the tropical forests of Africa, India, and South-east Asia.
The family was widespread and successful from the Oligocene (34 million years ago) to the Miocene (about 5 million years ago), but has remained almost unchanged over that time and remains as an example of primitive ruminant form. Chevrotains have a four-chambered stomach to ferment tough plant foods, but the third chamber is poorly developed. They do not have horns or antlers, and their short, thin legs leave them lacking in agility.
The largest member of the family is the Water Chevrotain of Africa, at about 80 cm in length and roughly 10 kilos. It is regarded as the most pig-like and primitive of the four. The remaining three all prefer rocky forest habitats. The Lesser Mouse Deer of South-east Asia is the smallest, and one of the smallest ungulates at around 45 cm and 2 kilos.
All four species depend for their survival on the retention of their fast-dwindling forest habitat and restriction of the bush meat trade.