 Early fossil remains were fragmentary , which led to much speculation on the posture and nature of Iguanodon . Iguanodon was initially portrayed as a quadrupedal horn @-@ <unk> beast . However , as more bones were discovered , Mantell observed that the forelimbs were much smaller than the hindlimbs . His rival Owen was of the opinion it was a <unk> creature with four pillar @-@ like legs . The job of overseeing the first lifesize reconstruction of dinosaurs was initially offered to Mantell , who declined due to poor health , and Owen 's vision subsequently formed the basis on which the sculptures took shape . Its bipedal nature was revealed with the discovery of the Bernissart skeletons . However , it was depicted in an upright posture , with the tail dragging along the ground , acting as the third leg of a tripod . 
