March 14, 2007 From Jaw to Ear: Transition Fossil Reveals Ear Evolution in Action Now hear this: early mammal fossil shows how sensitive ear bones evolved The mammal ear is a very precise system for hearing—enabling everything from human appreciation of music to the echolocation of bats. Three tiny bones known as ossicles—the hammer (malleus), anvil (incus) and stirrup (stapes)—work together to propagate sound from the outside world to the tympanic membrane, otherwise known as the eardrum. From there, the sound is transmitted to the brain and informs the listener about pitch, intensity and even location. But it has...