Practically everyone has owned a teddy bear as a child, but not everyone realizes that the animal it is modeled on is not a bear at all. Bears are placental mammals whereas the Koala, which is often called the Australian teddy bear, is another marsupial number of marsupials restricted to the Australian region look mammal grouped with the phalanger family. It is interesting that and acts like placental mammals found on other continents. The gliding phalanger is very much like the flying squirrel for example.
Why is this?
About fifty million years ago Australia became cut off from the other continents as the mammals evolved. This allowed the marsupials to adapt themselves to live in every kind of habitat, free from competition from the more advanced placental mammals.
In every other continent the placentals flourished and replaced the marsupials so that apart from Australia (and America where some opossums have somehow managed to survive), marsupials are found nowhere else in the world.
So, on separate continents, representatives from two unrelated groups of mammals became adapted to live in all the available habitats. Where particular conditions were the same in either continent, the animals which evolved to suit them bear similarities in shape and behavior. This phenomenon is called parallel or convergent evolution.