If you want to find a useful list of the ancient Australian megafauna, the Wikipedia page is fairly good - with a good list of now extinct creatures.
http://en.wikipedia.org/wiki/Australian_megafauna
An excellent list of Internet sites are available at;
http://science.uniserve.edu.au/schoo...s/mgfauna.html
A good site with detailed information is from the Australian Museum.
I.e.
http://australianmuseum.net.au/Austr...xtinct-animals