 During his re @-@ examination of Iguanodon , David Norman was able to show that this posture was unlikely , because the long tail was stiffened with ossified tendons . To get the <unk> pose , the tail would literally have to be broken . <unk> the animal in a horizontal posture makes many aspects of the arms and pectoral <unk> more understandable . For example , the hand is relatively immobile , with the three central fingers grouped together , bearing <unk> @-@ like phalanges , and able to <unk> . This would have allowed them to bear weight . The wrist is also relatively immobile , and the arms and shoulder bones robust . These features all suggest that the animal spent time on all fours . 
