Why is the platypus found only in Australia?

Why do platypuses live only in Australia? The answer is probably in the timing. Most genetic and morphological analyses suggest that monotremes [1] predate other mammals [2], with marsupials [3] and placentals [4] coming a bit later. read more

In the regions of Australia in which the platypus is most commonly found (the eastern states), there are not many natural predators of mammals. In northern Queensland there are crocodiles and pythons which could prey on platypuses. read more

In 2004, researchers at the Australian National University discovered the platypus has ten sex chromosomes, compared with two (XY) in most other mammals (for instance, a male platypus is always XYXYXYXYXY), The sex chromosomes of the platypus have been found to have great homology to the bird Z chromosome. read more