Marsupia

Marsupia is a term that has been used historically and in some older classifications to refer to marsupials, which are a infraclass of mammals characterized by the females of most species having a pouch, or marsupium, in which they carry and nurse their young. These mammals are primarily found in Australia and the Americas. The term marsupia is not a formal taxonomic rank in current scientific usage, but it broadly encompasses this distinctive group of mammals.

The defining feature of marsupials is their reproductive strategy. Unlike placental mammals, marsupials give birth to very immature offspring, often referred to as 'joeys'. These underdeveloped newborns then crawl into the mother's pouch, where they attach to a nipple and continue their development for an extended period, receiving nourishment and protection. Prominent examples of marsupials include kangaroos, koalas, wallabies, opossums, and wombats. Their evolutionary history is distinct from that of placental mammals, and they represent a significant branch of mammalian evolution. The classification of marsupials has been refined over time, but the fundamental characteristic of having a pouch remains a key identifier for many species within this group.