What are the differences between mammals and mangles?

There are three groups of mammals: placental mammals, marsupials and monotrems. Monotremes include only platypus and four echidna species. The remaining mammals are all placenta or marsupials. Placental mammals are clearly dominant because it was more than 65 million years, with more than 5,500 species on each continent except Antarctica. Marsupials, with only 334 species, carved a niche for themselves in Australia, where to a large extent of displaced placental mammals. Marsupials are also located in small numbers in South America and Central America, with a single type (Virginia Opossum) in North America.

Marsupials and placental mammals are both mammals, ie the thermally distorted tetraps with sweat glands that provide milk for young and are covered in fur or hair. What distinguishes two apart from each other is 1) their way of reproduction, 2) genitalia and 3) their blood temperature, which is slightly smaller than the temperature of placental mammals. For many centuries, the marsupials were considered "primitive" SAMore, but there are few real evidence for it outside cultural bias. Because Marsupials occupy mainly Australia and the remote areas of South America, scientists were poorly characterized until the mid -18th century.

instead of staying in the womb, such as placental mammals, the warning strips leave the mother's body in a very early stage and climb from the genital opening to a special case with nipples for milk. This evolutionary strategy avoids the need for complex placenta to protect the growing fetus from the immune system of his mother. Marsupials and placental mammals have both developed at about the same time, about 125 million years ago, and although they have evolved separately since then, they showed significant parallel development because they have radiated from ancestors similar Shrew. For an occasional observer without prior knowledge of the species, the only way to distinguish marsupials from placental mammal is forExamine the genitals.

Some known marsupials include Koala, Kangaroo, Opssums, Vačice, Wombats, Tasmanian Devil, Marsupial Mice, Bandicoot and lesser-known species such as Marsupial Mole, Numbat, Bilby and Musk Rasa-Kangaroo. Placentary mammals include rodents, whales, elephants, otters, horses, cats, dogs, people and many others.