Came across an interesting report on the ABC News website saying that Platypus has 5 chromosomes determining gender as opposed to virtually the rest of the animal kingdom which makes do with 1. There are further articles on this at the ABC Science News website and at New Scientist.
There was this interesting quote in the New Scientist article:
Another intriguing discovery from the study is that one end of the platypuses’ chromosome chain shares similarities with mammalian sex chromosomes, while the other end shares characteristics with the sex chromosomes of birds.
Robin Williams was right.. 🙂