 Because it is both one of the first dinosaurs described and one of the best @-@ known dinosaurs , Iguanodon has been well @-@ placed as a barometer of changing public and scientific perceptions on dinosaurs . Its reconstructions have gone through three stages : the <unk> quadrupedal horn @-@ <unk> reptile satisfied the <unk> , then a bipedal but still fundamentally <unk> 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 . 
