At least your prof didn't put it up as a sign like the massive eden project (those big domes that you may have seen in the Bond film) did:
http://news.bbc.co.uk/1/hi/england/2788091.stm

>>A brief sweep of the web seems to indicate Australia has had the greatest number of mammalian extinctions in recent history, but i haven't found support for the 50% figure.<<

You win. Australia, with a population density of less than three per square kilometre(7.5 per square mile) has a very large proportion of the world's mammal extinctions to be proud of. I posted this to counter the usual rubbish that all the world's environment troubles are because 'people in the developing world
have too many babies'.

As for the figure, this page claims the figure is now down to 25%(due to the rest of the world 'catching up'):
http://www.wwf.org.au/tsn/TSN_about_plight.htm

While these pages claim the figure is one third:
http://audit.ea.gov.au/ANRA/docs/fas..._facts_35.html
http://www.smh.com.au/articles/2003/...777255475.html

In addition, all these creatures were entirely 'human compatible'. This compares to the somewhat harder to live with lion, elephant and rhino which are mostly still around. (Although the lion is endagered and four out of five species of rhino are critically endagered or functionally extinct).