Actually, ten arguments:
1 Sea mammal blowhole. Any animal that spends appreciable time in the ocean should be able to extract oxygen from water via gills. Enlarging the lungs and moving a nostril to the back of the head is a poor work-around.
2 Hyena clitoris. When engorged, this “pseudopenis,” which doubles as the birth canal, becomes so hard it can crush babies to death during exit.
3 Kangaroo teat. In order to nurse, the just-born joey, a frail and squishy jellybean, must clamber up Mom’s torso and into her pouch for a nipple.
