 One of the first details noted about Iguanodon was that it had the teeth of a herbivorous reptile , although there has not always been consensus on how it ate . As Mantell noted , the remains he was working with were unlike any modern reptile , especially in the toothless , <unk> @-@ shaped form of the lower jaw <unk> , which he found best compared to that of the two @-@ toed <unk> and the extinct ground <unk> <unk> . He also suggested that Iguanodon had a prehensile tongue which could be used to gather food , like a <unk> . More complete remains have shown this to be an error ; for example , the <unk> bones that supported the tongue are heavily built , implying a muscular , non @-@ prehensile tongue used for moving food around in the mouth . The <unk> @-@ tongue idea has also been incorrectly attributed to Dollo via a broken lower jaw . 
