The genus Canis includes wolves, coyotes, jackals, and domestic dogs. In the midwestern U.S. at least three members of the genus are found in sites that date from the last Ice Age. These three members are the dire wolf (Canis dirus), the grey wolf (Canis lupus) and the coyote (Canis latrans). One additional species, the domestic dog (Canis familiaris), was almost certainly also present at the very end of the Pleistocene.

The grey wolves and coyotes of the last Ice Age were probably very similar in look and behaviour to their modern relatives.

The dire wolf was not quite like any animal we have today. It was similar in overall size and mass to a large modern grey wolf. This means it was about 5 feet long and weighed about 110 pounds on average. The dire wolf looked fairly similar to the modern grey wolf but there were several important differences. The dire wolf had a larger, broader head and shorter, more sturdy legs than its modern counterpart and its teeth were much larger and more massive. The braincase of the dire wolf is also smaller than that of a similarly-sized grey wolf.

The fact that the lower part of the legs of the dire wolf are proportionally shorter than those of the gray wolf, indicates that the dire wolf was probably not a good a runner as the gray wolf.

Many paleontologists think that the dire wolf may have used its relatively large, massive teeth to crush bone and this idea is supported by the fact that dire wolf teeth frequently have large amounts of wear on their crowns. Several people have suggested that dire wolves may have made their living in similar ways to the modern hyenas. Wolves and coyotes are relatively common large carnivores found in Ice Age sites, in fact several thousand dire wolves have been found in the asphalt pits at Rancho La Brea in Los Angeles. The first specimen of a dire wolf was found at near Evansville, Indiana.

The genus Canis underwent a mixed fate at the end of the Pleistocene. The grey wolf and coyote survived the extinction that occurred approximately 10,000 years ago but the dire wolf did not. It is possible that the dire wolf depended on scavanging the remains of the large herbivores of the last Ice Age. The extinction of these herbivores may have then led to the extinction of the dire wolf. Scientists do not know if this is the case, but they continue to search for the reason that many kinds of mammals became extinct about 10,000 years ago.

The evolution of these three species of canids is interesting stuff. Paleontologists think that, although all three of the species were found in the same area at the same time, each comes from a different evolutionary lineage within the genus Canis. That is, none of these three species is the direct ancestor of either of the other two species.