The wild yak (Bos mutus) is a large, wild cattle native to the Himalayas. It is the ancestor of the domestic yak (Bos grunniens).

The wild yak is among the largest extant bovid species. Adults stand about 1.6 to 2.05 m (5.2 to 6.7 ft) tall at the shoulder, and weigh 500–1,200 kg (1,100–2,600 lb). The head and body length is 2.4 to 3.8 m (7.9 to 12 ft), not counting the tail of 60 to 100 cm (24 to 39 in).^[4] The females are about one-third the weight and are about 30% smaller in their linear dimensions when compared to bull wild yaks. Domesticated yaks (Bos grunniens) are somewhat smaller.^[5][6][7][8]

They are heavily built animals with a bulky frame, sturdy legs, and rounded cloven hooves. To protect against the cold, the udder in females and the scrotum in males are small, and covered in a layer of hair. Females have four teats. Both sexes have long shaggy hair, with a dense woolly undercoat over the chest, flanks, and thighs for insulation against the cold. In males especially, this undercoat may form a long “skirt” that can reach the ground. The tail is long and horse-like, rather than tufted like the tails of cattle or bison. The coat is typically black or dark brown, covering most of the body, with a grey muzzle (although some wild golden-brown individuals have been reported). Wild yaks with gold coloured hair are known as the wild golden yak (Chinese: 金色野牦牛; pinyin: jīnsèyě máoniú). They are considered an endangered subspecies in China, with an estimated population of 170 left in the wild.^[9]

(From Wikipedia, June 2021)