 Dollo 's specimens allowed him to show that Owen 's prehistoric <unk> were not correct for Iguanodon . He instead modelled the skeletal mounts after the cassowary and <unk> , and put the spike that had been on the nose firmly on the thumb . He was not completely correct , but he also had the disadvantage of being faced with some of the first complete dinosaur remains . A problem that was later recognised was the bend he introduced into the tail . This organ was more or less straight , as shown by the skeletons he was excavating , and the presence of ossified tendons . In fact , to get the bend in the tail for a more <unk> or <unk> @-@ like posture , the tail would have had to be broken . With its correct , straight tail and back , the animal would have walked with its body held horizontal to the ground , arms in place to support the body if needed . 
