Or anything, heck, it is true, I just don't get it. Opossums are marsupials, and the obviously live in North America. Tell me of any other modern marsupials that are not found in Austrialia, I am curious to know of any more. I did not read Rich's biogeographical argument, so I shall make no claims to be supporting it.
Marsupials support both the claim that the earth is ancient and that evolution occured.
Since both mammals and marsupials exist on other continents, some situation must have arisen to account for this exceptional situation. Tectonic theory predicts that some time ago austrailia was connected to the rest of the continents before becoming an island. Marsupials were predominantly the type of mammal in the past and were the only type of mammal, in addition to monotremes, to survive and thrive to modern day times. Meanwhile placental mammals developed alongside marsupial mammals on one of the other continents, and proceed to eventually outnumber marsupials in species proportions on the non-Austrailian continents. It is not the fact that marsupials are rarely found off of Austrailia that is of support for an ancient Earth and evolution, it is that placental mammals are not found natively in Austrailia that is of importance.