 Iguanodon teeth are , as the name suggests , like those of an iguana , but larger . Unlike hadrosaurids , which had columns of replacement teeth , Iguanodon only had one replacement tooth at a time for each position . The upper jaw held up to 29 teeth per side , with none at the front of the jaw , and the lower jaw 25 ; the numbers differ because teeth in the lower jaw are broader than those in the upper . Because the tooth rows are deeply <unk> from the outside of the jaws , and because of other anatomical details , it is believed that , as with most other ornithischians , Iguanodon had some sort of cheek @-@ like structure , muscular or non @-@ muscular , to retain food in the mouth . 
