Most birds, such as chickens, owls, and penguins, have no teeth. They use their beaks to peck, tear, or crush food. A muscular section of their belly, the gizzard, assists in grinding food, filling the gap that is left when there are no teeth. Some birds swallow tiny stones to assist the gizzard in grinding hard seeds. Their beaks and claw capability of handling food render teeth obsolete. Birds’ evolution illustrates how flight capabilities, beak structure, and digestive compensations render chewing unnecessary.
