What sequence of events resulted in this region having animals and plants that are different from those found anywhere else? (19 points for best answer! )

this is an open response question, and i just dont know what to say. if you could , that would be great. and .

I believe that the question refers to Australia and to the fact that it's been very isolated and that as a result it has developed a number of species which cannot be found anywhere else.
The series of events here would be 1) the geographical isolation of Australia  (it separated from the other lands 99 million years ago) and 2) the frequent  changes in climate it experienced which led to population bottlenecks (for example it was initially very warn and then it experienced a colder period)