Metatheriaan
Metatheria is a infraclass of mammals that, along with Eutheria (placental mammals) and Monotremata (monotremes), constitutes the class Mammalia. The defining characteristic of metatherians, commonly known as marsupials, is their reproductive strategy. Unlike placental mammals, which have a long gestation period where the fetus develops internally within the uterus nourished by a placenta, marsupials typically have a very short gestation period. The young are born in a relatively undeveloped state, often described as embryonic or fetal. After birth, these underdeveloped young crawl to a pouch, or marsupium, located on the mother's abdomen. Inside the pouch, they attach to a nipple and continue their development, receiving nourishment and protection until they are mature enough to survive outside.
The majority of extant marsupial species are found in Australia and surrounding islands, though a significant
The diversity within Metatheria is considerable, encompassing a wide range of forms from the small, insectivorous