The grey wolf, or gray wolf, (Canis lupus, also known as the timber wolf, or simply wolf, is the largest wild canid, with height ranging from 0.6 to 0.95 m (26-38 in) and weight from 20 to 65 kg (44-150 lb), with a record of 86 kg (189 lb). The grey wolf evolved in the Late Pleistocene, about 300,000 years ago, and is a survivor of the last glacial period, during which much of Eurasia and North America were covered in ice caps. The grey wolf's former range extended across most of Eurasia and North America, but it has been extirpated among much of it, especially in the United States and Europe.
Wolves are social animals that hunt in packs with an average of eight members. As one would gather from their name, grey wolves are mostly grey, though they shed their coats in spring or summer, giving them a pale milky tone. Some groups have a wide variety of coat colors, ranging across the entire canine color spectrum, including white, red, brown, and black. Desert subspecies of the wolf have the milky tone year-round. Aside from Italy, where about a quarter of wolves are black, black grey wolves are only found in North America.
Highly adaptable, the grey wolf can thrive in temperate forests, mountains, deserts, taiga, tundra, grasslands, and some urban areas. They have the longest and most powerful snout of wild canids, which can be used to distinguish them from other canids such as coyotes and jackals, which have a narrower snout. Compared to domestic dogs (which are categorized as a subspecies of the grey wolf), they have longer legs, yellow eyes, larger paws, and bigger teeth. A wolf can bite down with 1,450 lbs of force per square inch.
The grey wolf is extremely territorial and quite ruthless. The pack, which usually consist of a couple and their offspring, hunts together, and is capable of taking down large animals like deer or buffalo. When the pups of the pack reach sexual maturity, tensions increase, and in some cases the children kill the parents or vice versa. Wolves that act unusual, such as epileptic wolves, or injured wolves are often killed by the members of their pack. A study of wolves in Minnesota found that 14-56% of wolf deaths were due to predation by other wolves.