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Hyenas or hyaenas (from Greek ὕαινα hýaina) are any feliform carnivoran mammals of the family Hyaenidae /haɪˈɛnɪdiː/. With only four extant species, it is the fifth-smallest biological family in the Carnivora, and one of the smallest in the class Mammalia. Despite their low diversity, hyenas are unique and vital components of most African ecosystems. Although phylogenetically they are closer to felines and viverrids, hyenas are behaviourally and morphologically similar to canines in several elements of convergent evolution; both hyenas and canines are non-arboreal, cursorial hunters that catch prey with their teeth rather than claws. Both eat food quickly and may store it, and their calloused feet with large, blunt, nonretractable claws are adapted for running and making sharp turns. However, the hyenas’ grooming, scent marking, defecating habits, mating and parental behaviour are consistent with the behaviour of other feliforms. Spotted hyenas may kill as many as 95% of the animals they eat, while striped hyenas are largely scavengers. Generally, hyenas are known to drive off larger predators, like lions, from their kills, despite having a reputation in popular culture for being cowardly. Hyenas are primarily nocturnal animals, but sometimes venture from their lairs in the early-morning hours. With the exception of the highly social spotted hyena, hyenas are generally not gregarious animals, though they may live in family groups and congregate at kills.
Hyenas first arose in Eurasia during the Miocene period from viverrid-like ancestors, and diversified into two distinct types: lightly built dog-like hyenas and robust bone-crushing hyenas. Although the dog-like hyenas thrived 15 million years ago (with one taxon having colonised North America), they became extinct after a change in climate along with the arrival of canids into Eurasia. Of the dog-like hyena lineage, only the insectivorous aardwolf survived, while the bone-crushing hyenas (including the extant spotted, brown and striped hyenas) became the undisputed top scavengers of Eurasia and Africa.Hyenas feature prominently in the folklore and mythology of human cultures with which they are sympatric. Hyenas are commonly viewed as frightening and worthy of contempt. In some cultures, hyenas are thought to influence people’s spirits, rob graves, and steal livestock and children. Other cultures associate them with witchcraft, using their body parts in traditional African medicine.
Hyenas originated in the jungles of Miocene Eurasia 22 million years ago, when most early feliform species were still largely arboreal. The first ancestral hyenas were likely similar to the modern banded palm civet; one of the earliest hyena species described, Plioviverrops, was a lithe, civet-like animal that inhabited Eurasia 20–22 million years ago, and is identifiable as a hyaenid by the structure of the middle ear and dentition. The lineage of Plioviverrops prospered, and gave rise to descendants with longer legs and more pointed jaws, a direction similar to that taken by canids in North America.
By 10–12 million years ago, the hyena family had split into two distinct groups: dog-like hyenas and bone-crushing hyenas. The arrival of the ancestral bone-crushing hyenas coincided with the decline of the similarly built family Percrocutidae. The bone-crushing hyenas survived the changes in climate and the arrival of canids, which wiped out the dog-like hyenas, though they never crossed into North America, as their niche there had already been taken by the dog subfamily Borophaginae. By 5 million years ago, the bone-crushing hyenas had become the dominant scavengers of Eurasia, primarily feeding on large herbivore carcasses felled by sabre-toothed cats. One genus, Pachycrocuta, was a 200 kg (440 lb) mega-scavenger that could splinter the bones of elephants. With the decline of large herbivores by the late ice age, Pachycrocuta was replaced by the smaller Crocuta.