Animals that travel in packs include members of the dog family, carnivorous dinosaurs and mules. Dogs, wolves, African wild dogs, dholes, bush dogs, dingos and coyotes often travel in packs, while foxes and raccoon dogs are usually seen in pairs or small family groups.
African wild dog packs can have up to 40 members. Canine packs are led by an alpha animal. Sometimes, only the alpha male and female are allowed to mate.
Some scientists believe that meat-eating dinosaurs such as allosaurs hunted in packs, though there is some dispute about this. Though the fossilized bones of these dinosaurs have been found together, these animals may have simply been fighting each other over a kill.
Mules are a bit of a special case for equines because a group of mules is called a pack as opposed to a herd, as is the case for horses, donkeys and zebras. Mules, the result of cross-breeding male donkeys with female horses, have long been used as pack animals. As with many hybrid animals, mules are sterile because the chromosome count of their parents is different. Mules are prized by humans because they can be as strong and fast as horses but are tougher.