Platypuses are weird

"Scientists from the Australian National University have proved what many have thought for years - platypuses are really weird.
In the international Nature journal today they report a platypus has five chromosomes determining sex, not one - like the rest of the species in the world.
Professor Jennifer Graves says platypuses have five X and five Y chromosomes, and when sperm are made it gets even stranger.
"What we've discovered is that these five Xs and five Ys line up in a great big long chain, that go XY XY XY XY XY XY, and then all the X chromosomes move to one pole, and all the Y chromosomes move to the other," she said.
Professor Graves says there is another unexpected finding.
"One end of the chain looks like human sex chromosomes but the other end of the chain looks like bird sex chromosomes, so the chain is actually linking a very ancient system of sex determination in birds and probably reptiles too," she said.
The unique status of the Australian mammal is now unassailable."
----ABC News

I wonder if Stephen Maturin ever got to study platypuses.