Information about Marsupials
Marsupials are mammals that have an external pouch (marsupium) in which the immature young are raised after birth until early infancy. Due to early birth, the young are born undeveloped, and they crawl in to the mother's pouch to grow further. Marsupials are found in Australia, Central And South America, New Zealand and on a few islands in the Pacific. Kangaroos, wallabies, koalas and opossums are the most commonly known marsupials.
The pouch
All marsupials do not have a permanent pouch. It is formed by a temporary fold of the skin that swells up to from a sac during the breeding season and disappears after the baby has developed. Usually, carnivorous mammals such as quolls, dunnarts and phascogales have a temporary pouch. Inside the pouch, the newborns are permanently attached to the mother's nipple. Once they grow, they live the pouch and return only when theyy feel threatened or to sleep. Kangaroos and wallabies allow their young to stay in the pouch even after the young once are capable of managing on their own. A few marsupials do not have a pouch at all.Evolution
Marsupials and placental mammals branched out from monotremes during the Cretaceous Period. The primitive marsupials and four pairs of molar teeth in each jaw, while the placental mammals didn't have more than three pairs. Sinodelphys szalayi is the earliest known marsupial. It lived in China around 125 million years ago. After the division of the supercontinent Pangaea, the marsupials finally found themselves inhabiting Australia. the wide variety of marsupials seen today evolved in Australia. In the resent times, modern marsupials seem to have reached the islands of Borneo or Sulawesi through Australia.
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