deep snow that covers most of its geographical range in winter. The ears are relatively small and triangular. The wolf's head is large and heavy, with a wide forehead, strong jaws and a long, blunt muzzle. The skull is in length and in width. The teeth are heavy and large, making them better suited to crushing bone than those of other canids. They are not as specialized as those found in hyenas though. Its molars have a flat chewing surface, but not to the same extent as the coyote, whose diet contains more vegetable matter. Females tend to have narrower muzzles and foreheads, thinner necks, slightly shorter legs, and less massive shoulders than males. Adult wolves measure in length and at shoulder height. The tail measures in length, the ears in height, and the hind feet are . The size and weight of the modern wolf increases proportionally with latitude in accord with Bergmann's rule. The mean body mass of the wolf is , the smallest specimen recorded at and the largest at . On average, European wolves weigh , North American wolves , and Indian and Arabian wolves . Females in any given wolf population typically weigh less than males. Wolves weighing over are uncommon, though exceptionally large individuals have been recorded in Alaska and Canada. In central Russia, exceptionally large males can reach a weight of . Pelage The wolf has very dense and fluffy winter fur, with a short undercoat and long, coarse guard hairs. Most of the undercoat and some guard hairs are shed in spring and grow back in autumn. The longest hairs occur on the back, particularly on the front quarters and neck. Especially long hairs grow on the shoulders and almost form a crest on the upper part of the neck. The hairs on the cheeks are elongated and form tufts. The ears are covered in short hairs and project from the fur. Short, elastic and closely adjacent hairs are present on the limbs from the elbows down to the calcaneal tendons. The winter fur is highly resistant to the cold. Wolves in northern climates can rest comfortably in open areas at by placing their muzzles between the rear legs and covering their faces with their tail. Wolf fur provides better insulation than dog fur and does not collect ice when warm breath is condensed against it. In cold climates, the wolf can