Coyote (Canis latrans) was one of the most successful predators of North America in late Holocene epoch. In Neocene coyote descendants had radiated to numerous species of predators of New and Old World. Among them Nearctic hyena-toother (Neohyaenognathus macrodens) is remarkable – it is huge canid having the certain features of saber teeth. Hyena-toothers did not become true saber-toothed predators, because during the evolution process they had adapted to carrion eating. But one canid descended from the same ancestors as hyena-toother turned to the real saber-toothed predator. It is atshehaske, huge saber-toothed coyot. The name “atshehaske” descends from Great Coyote – the Supreme deity of Havajo Indians. Like its “divine namesake” atshehaske differs in complex behaviour – this predator has remarkable cunning, insidiousness and nasty customs. The Latin name of species means “regal saber-toothed dog” and emphasizes appearance of this animal as well as possible. Atshehaske is extraordinary beautiful and majestic animal. It is built lighter, rather than hyena-toother (the maximal weight of atshehaske does not exceed 150 kg.), and has more graceful proportions. The reddish skin of atshehaske is patterned with beautiful spots and strips of yellowish-grey, brownish and black colors. Males have beautiful yellowish-grey shabrack with reddish shade, and females lack of it. On paws there are cross strips breaking to separate spots on shoulders and hips. Tail is short enough, but fluffy, with black tip. Like hyena-toother, atshehaske has sloping back, but on the whole its constitution is much more graceful. Muzzle of atshehaske is rather short. The extended obverse part of a muzzle characteristic for coyotes evolved to rather massive forward part of the lower jaw. The upper jaw smoothly passes into powerful and strong forehead. Prominent feature of the upper jaw is the presence of huge canines – up to 25 cm long at males and up to 20 cm at females. Animal has large enough peaked ears on which tips there are beautiful brushes of yellowish-grey fur. In the whole, despite of low, flat and massive forehead, atshehaske is rather majestic animal. On a way of hunting atshehaske is the real analogue of extinct large saber-toothed cats. It is an ambush hunter for large prey, unting in small groups. Attacking its prey atshehaske knocks it down and puts a bite. The predator uses canines as daggers – at the moment of bite in neck of prey canines of atshehaske simultaneously injure the large blood vessels carrying blood to brain and block respiratory ways. Prey dies from asphyxia and the termination of blood supply of brain. One more way of prey killing is putting large deep wounds in prey's belly, that causes fast death from bleeding. Atshehaske hunts most effectively in thickets of grass at riverbanks and shores of lakes where large mammals come to watering place. Atshehaske is a social species, like the most part of canid species, and lives in clans united by consanguinity (usually patrilineal). Each clan jealously protects the hunting territory, marking its borders with urine. The courtship season begins in winter. At this time males gather near the lair of female ready to pairing, and arrange severe duels for the right of pairing. They do not use canines against contenders, but tear skin of each other by incisors, pulling out large pieces of wool and skin. But direct skirmish of competing males happens rather seldom. Usually duels are limited to demonstration of canines and an exchange of ritual poses. After pairing male stays with the female and in common they build a lair – wide hole under roots of tree. Animals also frequently occupy caves of natural origin. Male feeds up the female and stays with her until while his puppies will become independent. In litter it may be up to 3 – 4 puppies which will become independent hunters at the age of approximately one and half years. After posterity rearing the female has the year long break in breeding, and at this time male can couple to another female. Life expectancy of atshehaske makes about 30 years. This species of canids in Neocene is at the edge of extinction due to rather recent occurrence in their area of saber-toothed cat missopeho, the large predator. Populations of atshehaske are isolated also, and gene exchange between them proceeds slowly. Therefore small populations quickly degenerate because of inbreeding depressions. The most successful populations of this species live in Rocky Mountains and in mixed forests of the north. The large population lives in Appalachian Mountains, and along the northern border of prairies this species is present as small isolated populations. In significant area of northern forests this species was superseded by missopeho.