The largest species in the genus Canis, the Hydni, has a shoulder height of 1.2 meters and an estimated weight of 95-120 kilograms, which is twice the size of the North American gray wolf. The sturdy physique and tenacious collective strength made these terrifying animals a nightmare for many vegetarians in North America at that time. The emergence of the upper dog was due to the decline of the canine bear family, which allowed them to turn passive into active and deliver fatal blows to their opponents, thus replacing half of the dominance of canine bears. The Terridae subfamily not only suppressed the development of the Canidae family in North America, but also eliminated its own ancestral group, led by the Osborn dog, which can weigh up to 50 kilograms.