An article about divergent evolution of marsupials in Australia, and a little info on what led to the development of these different animals.
Divergent evolution what is it? Divergent evolution happens when two different species evolve separately on say two different continents but nonetheless develop into similar species even though they may not share much if any common DNA.
Divergent evolution has occurred on all continents as they slowly separated from one another. The best-case example are the animals of Australia. All of the animals that are mammals except for Dingos are marsupials. None of the marsupials on Australia share more than a small amount of genetic material with any other mammal. Australia is the only continent around the globe where marsupials have not only survived but flourished.
More than 100 million years ago Australia split from Africa and Asia. At that time the only mammals around the globe consisted of very small mouse like creatures. As Australia spit over time the animals that evolved developed completely cut off from the rest of the world. Australia is the only continent in which marsupials have survived, the only marsupial the inhabits North America is the Opossum.
More then 100 million years ago marsupials were very common throughout the world but gradually as time wore on they became extinct everywhere except Australia and South America. When South America rejoined North America all of the marsupials except for the opossum quickly went extinct.
Gradually over time the marsupials in Australia expanded their size and shape to meet the needs of the environment. Along the way many adopted similar sizes and shapes of the other placental mammals all over the rest of the world.
Nearly one hundred percent of all the native animals of Australia are marsupials. As an example of marsupials filling the same bill as mammals, there are marsupial moles, mice and many others that share many of the same characteristics that mammals have. Marsupials are in a way primitive mammals, their dentition reflects those of early mammals.