The dire wolf was never really a wolf
For more than a century the dire wolf sat in the same genus as wolves, dogs and coyotes. Then a 2021 genetic study showed it belonged to an ancient American lineage that had split off before Canis even existed, and had never interbred with it.
Carl Linnaeus created the genus Canis in 1758 for the domestic dog, wolves, coyotes and jackals. Its members share 78 chromosomes and can potentially interbreed. They are medium to large animals with heavy skulls and teeth, long legs and fairly short ears and tails. Classification keeps shifting: in 2019 experts recommended moving the side-striped and black-backed jackals into a genus of their own, Lupulella, because DNA placed them outside the group.
The family tree runs deep. A fox-like genus, Leptocyon, lived from about 24 million years ago and split into foxes and canines 11.9 million years ago. In North America a jackal-sized ancestor gave rise to the first Canis around 6 million years ago in the south-western United States and Mexico, followed by Canis lepophagus, ancestor of wolves and coyotes. In the Old World, Canis evolved around 5 million years ago and then exploded across Eurasia about 1.8 million years ago in the so-called wolf event, linked to spreading mammoth steppe and ice sheets. An extinct subgroup, Xenocyon, meaning strange wolf, gave rise to the dhole and the African wild dog.
Teeth reveal diet. In carnivores the upper fourth premolar and lower first molar work like scissors to slice muscle and tendon; on that lower molar a front slicing section and a rear grinding section occur in proportions that indicate how meat-heavy an animal's diet is. Measured for body size, the dire wolf had the strongest canine bite of any placental predator studied, at 163 newtons per kilogram, ahead of the African hunting dog at 142, the grey wolf at 136, the dhole and the dingo.
Males and females look much alike. Most species live in monogamous pairs, and wolves, coyotes and jackals form groups built around a breeding pair and its young. Since a wolf cannot grapple with its forelimbs, bringing down prey bigger than itself depends on its jaws and on teamwork.
Source: Canis
