Whales are descendants of land-dwelling mammals of the artiodactyl order (even-toed ungulates). Dolphins are descendants of land-dwelling mammals of the artiodactyl order (even-toed ungulates). Tahrs are a species of large Asian artiodactyl ungulates related to the wild goat. Elomeryx is an extinct genus of artiodactyl ungulate, and is among the earliest known anthracotheres. An okapi is a giraffid artiodactyl mammal native to the Ituri Rainforest in central Africa. Indohyus is a genus of extinct digitigrade artiodactyl known from Eocene fossils in Asia. The order of Artiodactyl includes all even-hooved mammals. Suidae is a family of artiodactyl mammals which are commonly called pigs, hogs or boars. The family Raoellidae is said to be the closest artiodactyl family to the cetaceans. Proantilocapra is an extinct genus of the artiodactyl family Antilocapridae. Osbornoceros is an extinct artiodactyl genus of the family Antilocapridae. Merycodus is an extinct genus of the artiodactyl family Antilocapridae. Rusingoryx is a genus of extinct alcelaphine bovid artiodactyl closely related to the wildebeest. There are about 220 artiodactyl species worldwide, including many that are of great economic importance.