At the top of the skull, there are 2 rows of teeth, and that’s really unusual – normally, you’d just expect 1 row of teeth in the upper jaw. There’s some differences there in the way they feed. A tuatara, for instance, when it catches food will actually catch food like that and slide the lower jaw like this, whereas a lizard has got more flexibility in the bones of the skull, and it can actually arch the bones over like that and meet them at the front of the mouth, and it doesn't move the lower jaw, just swallows – it chews a bit and swallows. So a very different way of feeding, and that may be one of the reasons why lizards are more successful today. There’s a lot more species of lizards than there are of tuatara and their relatives.
Acknowledgement: University of Waikato