The hyenas, also members of the order Carnívora, appeared only relatively recently, in Mid-Miocene times, about 15 million years ago. They probably evolved on the African continent, and then spread throughout the Old World.
The only hyena known from the New World is Ch.asmaporth.etes, which lived in North America during the Pleistocene. It also lived throughout Africa, Asia and Europe. It was a fast-running hunter rather than a scavenger, and its legs and teeth were similar to those of the modern cheetah. Indeed, in Africa it had to compete with the true cheetahs, which also lived there during Pleistocene times.
The role of "mammalian scavenger" in North America was played chiefly by the heavy-toothed borophagine dogs, such as Osteoborus (above). Their diet and lifestyle mirrored that of the hyenas elsewhere in the world.
Today, hyenas are restricted to the warmer areas of Africa and Asia. Although they are chiefly scavengers, they are also agile and intelligent hunters, running in packs to bring down swift-footed grazing mammals. They have heavy bone-crushing teeth, and their remarkably tough digestive system enables them to absorb the organic matter in bone, while indigestible bone fragments, hooves, horns, ligaments and hair are regurgitated as pellets.
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