The fur of the mountain gorilla, often thicker and longer than that of other gorilla species, enables them to live in colder temperatures. Gorillas can be identified by nose prints unique to each individual. Males, at a mean weight of 195 kg (430 lb) upright standing height of 168 cm (66 in) usually weigh twice as much as the females, at a mean of 100 kg (220 lb) and a height of 140 cm (55 in).
š š¦šØš© This subspecies is smaller than the eastern lowland gorilla, the other subspecies of eastern gorilla. Adult males have more pronounced bony crests on the very top and back of their skulls, giving their heads a more conical shape. These crests anchor the powerful temporalis muscles, which attach to the lower jaw (mandible). Adult females also have these crests, but they are less pronounced. Like all gorillas they feature dark brown eyes framed by a black ring around the iris. Adult males are called silverbacks because a saddle of gray or silver-colored hair develops on their backs with age. The hair on their backs is shorter than on most other body parts, and their arm hair is especially long.
Source: the_urbanhistorian
Wood, Gerald (1983). The Guinness Book of Animal Facts and Feats.