n.
Any mammal of the infraclass Marsupialia, characterized by premature birth and continued development outside the womb.
The young remain attached to the mother's teats for a period corresponding to the late stages of fetal development of a placental mammal. More than 170 species (e.g., bandicoots , kangaroos , koalas , wombats ) are found in Australia, New Guinea, and nearby islands. About 65 species of opossum occur in the Americas and seven species of ratlike marsupials in South America. Many species have a pouch (marsupium), a fold of skin covering the nipples on the mother's lower belly, where the young continue their development.