 The arms of I. bernissartensis were long ( up to 75 % the length of the legs ) and robust , with rather <unk> hands built so that the three central fingers could bear weight . The <unk> were conical spikes that stuck out away from the three main digits . In early restorations , the spike was placed on the animal 's nose . Later fossils revealed the true nature of the thumb spikes , although their exact function is still debated . They could have been used for defense , or for foraging for food . The little finger was elongated and <unk> , and could have been used to manipulate objects . The <unk> formula is 2 @-@ 3 @-@ 3 @-@ 2 @-@ 4 , meaning that the innermost finger ( <unk> ) has two bones , the next has three , etc . The legs were powerful , but not built for running , and each foot had three toes . The backbone and tail were supported and stiffened by ossified tendons , which were tendons that turned to bone during life ( these rod @-@ like bones are usually omitted from skeletal mounts and drawings ) . 
