Possum is a colloquial term for the American opposum. It is a marsupial because it's offspring are born extremely small and not fully developed the way placental mammals are. read more
It is a marsupial because it's offspring are born extremely small and not fully developed the way placental mammals are. The offspring then climb into the mother's pouch in which the offspring nurse and live until they are fully developed. Special note- a true possum is native to Australia, and is also a marsupial. read more