The tip of the upper jaw is beak-like and separated from the remainder of the jaw by a notch. There is a single row of teeth in the lower jaw and a double row in the upper, with the bottom row fitting perfectly between the two upper rows when the mouth is closed. This specific tooth arrangement is not seen in any other reptile; although most snakes have a double row of teeth in their upper jaws, their arrangement and function is different from the tuatara.