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Suidae is the biological family to which pigs belong. In addition to numerous fossil species, up to sixteen extant species are currently recognized, classified into between four and eight genera. The family includes the domestic pig, ''Sus scrofa domesticus'' or ''Sus domesticus'', in addition to numerous species of wild pig, such as the babirusa ''Babyrousa babyrussa'' and the warthog ''Phacochoerus aethiopicus''. All suids, or swine, are native to the Old World, ranging from Asia and its islands, to Europe, and Africa. The earliest fossil suids date from the Oligocene epoch of Asia, and their descendants reached Europe during the Miocene. Several fossil species are known, and show adaptations to a wide range of different diets, from strict herbivory to possible carrion-eating (in ''Tetraconodon''). ==Physical characteristics== Suids belong to the order Artiodactyla, and are generally regarded as the living members of that order most similar to the ancestral form. Unlike most other members of the order, they have four toes on each foot, although they walk only on the middle two digits, with the others staying clear of the ground. They also have a simple stomach, rather than the more complex, ruminant, stomach found in most other Artiodactyl families. They are small to medium animals, varying in size from in length, and in weight in the case of the pygmy hog, to and in the giant forest hog.〔()〕 They have large heads and short necks, with relatively small eyes and prominent ears. Their heads have a distinctive snout, ending in a disc-shaped nose. Suids typically have a bristly coat, and a short tail ending in a tassle. The males possess a corkscrew-shaped penis, which fits into a similarly shaped groove in the female's cervix. Suids have a well-developed sense of hearing, and are vocal animals, communicating with a series of grunts, squeals, and similar sounds. They also have an acute sense of smell. Many species are omnivorous, eating grass, leaves, roots, insects, worms, and even frogs or mice. Other species are more selective and purely herbivorous.〔 Their teeth reflect their diet, and suids retain the upper incisors, which are lost in most other Artiodactyls. The canine teeth are enlarged to form prominent tusks, used for rooting in moist earth or undergrowth, and in fighting. They have only a short diastema. The number of teeth varies between species, but the general dental formula is: 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Suidae」の詳細全文を読む スポンサード リンク
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