A class of animals known as Marsupials is a characteristic feature of

1. Marsupials are a group of mammals characterized by premature birth and continued development of the newborn while attached to the nipples on the mother's lower belly, often within a pouch. 2. Australia became isolated from other continents early in the Cenozoic Era, allowing its unique fauna, including a wide variety of marsupials, to evolve with relatively little competition from placental mammals which dominate elsewhere. 3. While some marsupials exist in the Americas (like opossums), the greatest diversity and dominance as a characteristic feature is found in Australia.