Explain that oviparous and marsupial mammals are found predominantly in Australia.

It’s pretty simple from an evolutionary point of view. Millions of years ago, all continents were interconnected. But after the separation of the continents, development began in closed territories. The fauna of Australia is very different from the fauna of Africa, Eurasia and other continents. Evolution on each continent proceeded differently. This is the reason for the differences in different animals. Marsupials and oviparous mammals did well in Australia. Therefore, they were able to survive there and have lived for millions of years.