Old World monkeys are medium to large in size, and range from arboreal forms, such as the Colobus, to fully terrestrial forms, such as the baboons. The smallest is the talapoin, with a head and body 34–37 cm in length, and weighing between 0.7 and 1.3 kilograms, while the largest is the male mandrill at around 70 cm in length, and weighing up to 50 kilograms (the females are much smaller).