Because it is both one of the first dinosaurs described and one of the best @-@ known dinosaurs , Iguanodon have been well @-@ placed as a barometer of changing public and scientific perceptions on dinosaurs . Its reconstructions have gone through three stages : the elephantine quadrupedal horn @-@ snouted reptile satisfied the Victorians , then a bipedal but still fundamentally reptilian animal using its tail to prop itself up dominated the early 20th century , but was slowly overturned during the 1960s by its current , more agile and dynamic representation , able to shift from two legs to all fours .