Multiple sex genes make platypus weirder

The platypus just got even weirder.

Australian researchers have discovered that the curious mammal has 10 separate sex chromosomes - some of which show links to birds.

Humans have two sex chromosomes - the female X chromosome and the male Y chromosome.

Platypuses, it is now known, have five pairs of chromosomes made up of five Xs and five Ys. Multiple sex chromosomes occur in termites and spiders but what had been discovered in the platypus is believed to be unique in mammals.