australasia has been separated from other continents for many millions of years. in the main part of the continent, australia, 83% of mammals, 89% of reptiles, 90% of fish and insects and 93% of amphibians are endemic. its native mammals are mostly marsupials like kangaroos, bandicoots, and quolls. by contrast, marsupials are today totally absent from africa and form a small portion of the mammalian fauna of south america, where opossums, shrew opossums, and the monito del monte occur (see the great american interchange).