Certainly, looking at present-day hare it is difficult to suppose, that a huge animal can evolve from it. However the common ancestor of such large animals, as bulls, giraffes and hippopotamuses was the small long-legged animal Diacodexis (rabbit-sized mammal). It lived on the Earth in early Eocene, and already from early Miocene real hollow-horned ruminants are known. Thus, the increase of the size had taken place for a time interval from 25 to 30 million years. And presence already in late Paleocene and Eocene huge (rhinoceros- or elephant-sized) fossil herbivores (had evolved, certainly, from other ancestors, than modern hoofed mammals) shows that the increase of the body size under favorable conditions (presence of free ecological niches) can pass even faster: at the end of the Cretaceous period large herbivores (dinosaurs) had died out, having left set of free ecological niches which were occupied subsequently by giant herbivore animals (orders Dinocerata, Pantodonta and others).
These facts also enable to suppose, that lagomorph mammal can evolve to large animal for the time period from Holocene to Neocene (25 million years). The hare can be considered as the primitive form of running herbivore and it is possible to suppose, that from it there will evolve in the beginning to animal, similar by constitution to the deer or the antelope, and then it will turn to an aurochid - the massive animal similar to the bull.
Aurochid is the huge animal, in size it is like domestic cow and it weights up to 500 kg. Animal lives in woods, keeps by herds of 25 - 30 animals under the leading of the skilled female. The body of aurochid is covered with shaggy wool, to winter wool becomes thicker because of underfur layer increasing. Legs had turned to similarity of camel feet: they maintain weight of a body on marshy ground, help to dig out snow in winter. The tail is short, covered with very long hair (it reminds horse tail). Colouring of the body in summer is brown, brightening in winter. Legs are colored darker then trunk. On the back there passes the longitudinal black strip. Head is big, ears are lengthened, mobile, are located on sides of head. On the nose there is the area of very dense thick skin, assisting to dig out wood litter and snow. Aurochid feed in bushes and on forest edges, sometimes in the summer beast comes to bogs and lakes. Forage includes grass, leaves and bark of young sprouts, in summer and an autumn – mushrooms; in winter aurochid can eat even sponks. In winter the animal can dig out snow in searches of last year's grass, using legs and muzzle. To winter it becomes fat, on shoulders there appears the small hump.
The breeding period passes in the beginning of an autumn. This time males struggle with each other, having risen on back legs and pushing by chest. In the beginning of summer the female gives rise to 1 - 2 cubs. Cubs are advanced, with opened eyes, stay on legs in 1-st hour of life, are capable to follow mother after 3 - 4 hours after birth. Cubs are protected from predators by all herd. Voice of adult animals sounds as the snort, at aggression - hoarse low roar. Cubs utter a sound reminding the sheep bleating.