 In recognition of the resemblance of the teeth to those of the iguana , Mantell decided to name his new animal Iguanodon or " iguana @-@ tooth " , from iguana and the Greek word <unk> ( <unk> , <unk> or " tooth " ) . Based on isometric scaling , he estimated that the creature might have been up to 18 metres ( 59 feet ) long , more than the 12 metres ( 39 feet ) length of Megalosaurus . His initial idea for a name was Iguana @-@ <unk> ( " Iguana lizard " ) , but his friend William Daniel <unk> suggested that that name was more applicable to the iguana itself , so a better name would be <unk> ( " Iguana @-@ like " ) or Iguanodon . He neglected to add a specific name to form a proper binomial , but one was supplied in 1829 by Friedrich Holl : I. <unk> , which was later amended to I. anglicus . 
