The cheetah is built for running, with long limbs and powerful muscles that propel it along as it chases down its prey. But a new study has found that the world’s fastest land mammal has another, less obvious adaptation hidden away in its inner ear. Scientists suspected that the cheetah might also rely on a specialized vestibular system, the part of the inner ear that detects head movements and helps animals maintain their gaze and posture. Using computerized tomography scans, they created detailed 3D images of the inner ear from the skulls of cheetahs and other cat species, from leopards to domestic cats. They found that the vestibular system took up a much greater part of the inner ear in cheetahs than in any other cat. The cheetahs also had elongated semicircular canals, parts of the system involved in head movement and eye direction. These features help the animal catch dinner by letting it keep its head still and its eyes on the prize, even when the rest of its body is rapidly moving, the researchers write in Scientific Reports. The extinct giant cheetah did not have the same features, suggesting that the distinct vestibular system evolved fairly recently, they say.