Rhinoceros

As adults, all rhinoceroses weigh more than half a ton, making them some of the biggest megafauna still in existence. Their brains weigh 400–600 g (14–21 oz) for a mammal of their size, they have one or two horns, and their thick 1.5–5 cm (0.59–1.97 in) protective skin is made of layers of collagen arranged in a lattice arrangement.