A DNA study found the creatures to be a mix of mammal, bird and reptile with, even more strangely, 10 sex chromosomes

At first dismissed as a prank, and later cited as proof that God has a sense of humour, the duck-billed platypus has finally given up its evolutionary secrets

The creature, considered one of the strangest mammals in the world, has become the latest to have its genetic code sequenced, revealing it to be a bizarre mix of mammal, bird and reptile, with very complex sexuality. While humans have two sex chromosomes, the X and Y, the platypus has 10, with five of each kind

An international team of scientists extracted DNA from a female platypus, named Glennie, reading all 2.2bn pairs of her genetic "letters". Thought to have begun to diverge from other mammals 170m years ago, the platypus has been regarded as the nearest thing biologists have to a missing link between the earliest reptiles and mammals