North America indicates significantly greater abundances; therefore, the higher dire wolf numbers in the LaBrea region did not reflect the wider area. Assuming that only a few of the carnivores that were feeding became trapped, it is likely that fairly sizeable groups of dire wolves fed together on these occasions. The difference between the male and female of a species apart from their sex organs is called sexual dimorphism, and in this regard little variance exists among the canids. A study of dire wolf remains dated 15,360–14,310YBP and taken from one pit that focused on skull length, canine tooth size, and lower molar length showed little dimorphism, similar to that of the gray wolf, indicating that dire wolves lived in monogamous pairs. Their large size and highly carnivorous dentition supports the proposal that the dire wolf was a predator that fed on large prey. To kill ungulates larger than themselves, the African wild dog, the dhole, and the gray wolf depend on their jaws as they cannot use their forelimbs to grapple with prey, and they work together as a pack consisting of an alpha pair and their offspring from the current and previous years. It can be assumed that dire wolves lived in packs of relatives that were led by an alpha pair. Large and social carnivores would have been successful at defending carcasses of prey trapped in the tar pits from smaller solitary predators, and thus the most likely to become trapped themselves. The many A.d.guildayi and Smilodon remains found in the tar pits suggests that both were social predators. All social terrestrial mammalian predators prey mostly on terrestrial herbivorous mammals with a body mass similar to the combined mass of the social group members attacking the prey animal. The large size of the dire wolf provides an estimated prey size in the range. Stable isotope analysis of dire wolf bones provides evidence that they had a preference for consuming ruminants such as bison rather than other herbivores but moved to other prey when food became scarce, and occasionally scavenged on beached whales along the Pacific coast when available. A pack of timber wolves can bring down a moose that is their preferred prey, and a pack of dire wolves bringing down a bison is conceivable. Although some studies have suggested that because of tooth breakage, the dire wolf must have gnawed bones and may have been a