Marsupials are any members of the mammalian infraclass Marsupialia. All extant marsupials are endemic to Australasia and the Americas. A distinctive characteristic common to these species is that most of the young are carried in a pouch. Well-known marsupials include kangaroos, wallabies, koalas, possums, opossums, wombats, Tasmanian devils, and the recently extinct thylacines. Others include the numbat, the bandicoot, the bettong, the bilby, the quoll, the quokka, and the Potoroo.
Marsupials represent the clade originating from the last common ancestor of extant metatherians. Like other mammals in the Metatheria, they give birth to relatively undeveloped young that often reside with the mother in a pouch, for a certain amount of time. Close to 70% of the 334 extant species occur on the Australian continent (the mainland, Tasmania, New Guinea and nearby islands). The remaining 100 are found in the Americas — primarily in South America, but thirteen in Central America, and one in North America, north of Mexico.