The world can be divided into distinct biogeographical regions more or
less corresponding to the continents. In isolated geographic regions with
similar climatic conditions and habitats, present day populations of
species are more like those which existed there in the past than current
species in a different region. Even though Australia is in similar
latitudes and has similar climatic conditions and habitats to much of S
America and Africa, it has a distinctive fauna and flora such as:
* (platypus and echidna) are only found in Australia
* are totally absent in Africa and only represented by the opossums in S
America; the marsupials evolved to occupy niches in Australia which are
occupied by placental mammals elsewhere
* other than those introduced by humans, are noticeable by their
absence. (A recent fossil find, the jawbone of Ausktribosphinos nyktos, at
Inverloch, Victoria, has been dated at 115 million years old when Australia
was joined to Antarctica. The find has implications for re-interpreting the
origin and distribution of placentals worldwide).
* (porcupine grass) and are common in the arid areas of Australia but
not in those of America
