The weird and wonderful duck-billed platypus just got even more weird and more wonderful.
Platypuses are famous for laying eggs yet producing milk, having a bird-like bill and a skeleton with reptilian features. Now it turns out that the mammal has an equally eye-catching way of deciding its sex, according to a study by Frank Grützner and Jenny Graves at the Australian National University in Canberra, and colleagues.
In most mammals, including humans, sex is decided by the X and Y chromosomes: two Xs create a female, while XY creates a male. In birds, the system is similar: ZW makes for a female, while ZZ makes for a male.
But in platypuses, XXXXXXXXXX creates a female, while XYXYXYXYXY creates a male.
We here at ArchaeoBlog adore the platypus. Almost as much as sea slugs.
For more information about the humble platypus, see the Australian Platypus Conservancy or the Tasmanian government's platypus page (plus a movie!).
Lemurs are cool, too.