Marsupials include the wallaby, kangaroo, koala, wombat, Tasmanian devil, dasyure, phalanger and opossum. A marsupial wolf existed up until the 1950s when it went extinct, according to the University of California Museum of Paleontology.
Marsupials are mammals that are largely characterized by a pouch in which they carry their young. Like other mammals, they birth live young, but the young are little more than embryos that finish developing outside of the womb. The size of jellybeans, these young crawl up to their mothers' teats, usually located inside the pouch, where they suck and stay for months. Many marsupials such as the kangaroo and wallaby have pouches where this development takes place.
The red kangaroo is the largest living marsupial. The joey, or young kangaroo, lives in its mother's pouch for two months before reemerging. During the next eight months, the joey comes and goes from its mother's pouch, often in response to danger.
The majority of all marsupials are native to Australia, with a few species residing in South and North America. The opossum is the only marsupial native to the United States. However, marsupials were more common than placental mammals during the Mesozoic era until they started going extinct in the Tertiary period.