Platypus Sex Chromosomes Could Be Missing Link Between Mammals and Birds

Most people know by now that the duck-billed platypus is a pretty strange animal – one that doesn't meet the conventional classification of a mammal because of the fact that it lays eggs, like birds and reptiles. However, scientists have discovered something even more perplexing: the platypus has five pairs of sex chromosomes – not one pair, as is the case with most mammals.

The ten sex chromosome set of the male platypus follows a XYXYXYXYXY pattern. This is weird enough in its own right; but when studied, it was also realized that the platypus had chromosomal similarities to birds as well as mammals. The complex sex chromosomes of the platypus also resemble the ZZ/ZW sex chromosome system found in birds.

It was once believed that the sex determination processes of birds and mammals were autonomous, but this is no longer thought to be the case. "Mammal sex chromosomes may well have co-evolved with those of birds, and the platypus could be the key to finding out,"

Maugrim wrote:Christ the platypus really is one intriguing critter.. as if being able to detect the electrical fields of its prey, debilitating attackers with venom and spending more time in REM sleep than any other animal wasn't cool enough.