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 (14–21 oz) for mammals of their size, one or two horns, and a thick 1.5–5 cm (0.59–1.97 in), protective skin formed from layers of collagen positioned in a lattice structure.

Seal subfamily A traditionally distinguished subfamily of eared seals. Molecular genetic evidence suggests that some sea lions are more closely related to fur seals than to other sea lions, making both subfamilies paraphyletic groups.