Marsupial

Marsupial, common name for any of a large group of mammals, most of which carry their young in an abdominal pouch after birth. All are native to Australia, Tasmania, and New Guinea except for the opossums, and the shrew opossums of South America. Marsupials range from shrew size to the size of an adult human. Some smaller marsupials are the dunnarts; the Tasmanian devil; the tree-inhabiting cuscus (see Phalanger); the wallabies (see Kangaroo); the bandicoot; and the diurnal numbat, or banded anteater. Larger marsupials include the kangaroo, the koala, and the wombat. Marsupial fossils dating from the Pleistocene Epoch 1.5 million years ago have included even larger marsupials such as a wombat the size of a small car, the largest kangaroo ever known, and giant marsupial lions.

Female marsupials have two vaginas, which share a common opening but do not fuse. The placenta is not well developed, as it is in all other mammals except monotremes. The birth canal forms from an opening that develops in the connective tissue between the two vaginas and two uteri. The young are born in an incomplete state of development some two to five weeks after conception. Immediately after birth they enter the mother's abdominal pouch, in species that have pouches, or they simply anchor themselves to a teat, which expands to hold the young in place. They remain attached to a teat, inside a pouch or not, until old enough to forage for their own food. The penis of the male marsupial is forked, and the testes generally lie in front of the penis.

Scientific classification: Marsupials make up the superorder Marsupialia, which is divided into seven orders: (1) Didelphimorphia, American opossums; (2) Pancituberculata, American shrew opossums; (3) Microbiotheria, colocolos (or Monito del Monte) from Chile and Argentina; (4) Dasyuromorphia, carnivorous Australasian mammals, including the numbat; (5) Peramelemorphia, bandicoots, and bilbies from Australasia; (6) Notoryctemorphia, two species of marsupial mole from Australia; (7) Diprotodontia, koala, wombat, possums, kangaroos, and wallabies.