Drawing of dire wolf (Canis dirus) by Robert Larson
The genus Canis includes wolves, coyotes, jackals, and the 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 gray 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 (after about 12,000 years ago); however, none have been recovered in Pleistocene sites from the Midwest.
The gray wolves and coyotes of the last Ice Age were probably very similar in look and behavior to their modern relatives. The first specimen of a dire wolf was found at near Evansville, Indiana. The dire wolf was not quite like any animal surviving today. It was similar in overall size and mass to a large modern gray wolf. This means it was about 1.5 meters (5 feet) long and weighed about 50 kilograms (110 pounds) on average.
The dire wolf looked fairly similar to the modern gray wolf; however, there were several important differences. The dire wolf had a larger, broader head and shorter, more sturdy legs than its modern relative.
The teeth of dire wolf were much larger and more massive than those of the gray wolf. This specimen of a dire wolf upper jaw (maxilla) was excavated from a cave in Pulaski County, Missouri. Note the large, massive teeth. They may have been used to crush bones. The photograph to the right is a bottom view of a dire wolf left upper jaw
The braincase of the dire wolf was also smaller than that of a similarly-sized gray wolf. The jaws of the dire wolf and grey wolf also show the larger size of the dire wolf's teeth.
Many paleontologists think that the dire wolf may have used its relatively large, massive teeth to crush bone. 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 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, California. The coyote, gray wolf, and dire wolf have all been found in paleontological sites in the midwestern U.S.
The fact that the lower parts of the legs of the dire wolf are proportionally shorter than those of the gray wolf indicates that the dire wolf was probably not as good a runner as the gray wolf.
The genus Canis underwent a mixed fate at the end of the Pleistocene. The gray wolf and coyote survived the extinction that occurred approximately 11,500 years ago. The dire wolf, however, was one of the animals that did not survive. Perhaps 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; however, they continue to search for the reason that many kinds of mammals went extinct about 11,500 years ago.
The evolution of the genus Canis is a complex topic involving at least five continents. One model for the evolution of the genus Canis would be as follows:
The genus arose in North America sometime in the Late Miocene. A species of the genus entered Eurasia from North America via Beringia during the Late Miocene.
Coyotes derived from an exclusively North America lineage of the genus. This lineage is close to (or may be) C. leophagus.
The gray wolf, jackals, and hunting dogs derived from the Eurasian lineage. The gray wolf may have evolved from a wolf-like species such as C. etrucus. In the Early Pleistocene the gray wolf (Canis lupus) entered North America via Beringia.
The domestic dog is almost certainly derived from the gray wolf. Whether the wolf was domesticated just once or several times in different places is still a topic of much debate. More controversial ideas (from among others, Nowak, 1979 ) would include the following:
The red wolf (C. rufus) is derived from a North American lineage, perhaps from the Early Pleistocene species C. edwardsii or may be a sister taxon to that species.
The extinct North American dire wolf (C. dirus) evolved from a North American lineage. Possible sister taxa of the dire wolf include C. edwardsii, C. rufus, or the Middle Pleistocene genus C. arbrusteri. Kurten and Anderson, (1980) suggest that the dire wolf might be a sister taxon to C. nehringi from the Pleistocene of South America.
More information on the evolution of the genus Canis can be found in Kurten and Anderson, 1980, Martin, 1989, and Nowak, 1979.
This map shows some of the sites at which dire wolves, gray wolves, and coyotes have been found in the midwestern United States. Dire wolf (Canis dirus) finds are shown with green dots; gray wolf (Canis lupus) finds are shown as red squares; yellow triangles indicate coyote (Canis latrans) finds.
The sites on this map are all relatively well-dated and well-studied. These sites contain canid remains that are between 40,000 and 11,500 years old.