 Gorgosaurus shared its general body plan with all other tyrannosaurids . Its massive head was perched on the end of an S @-@ shaped neck . In contrast to its large head , its forelimbs were very small . The forelimbs had only two digits , although a third metacarpal is known in some specimens , the vestigial remains of the third digit seen in other theropods . Gorgosaurus had four digits on each hindlimb , including a small first toe ( hallux ) which did not contact the ground . Tyrannosaurid hindlimbs were long relative to overall body size compared with other theropods . The largest known Gorgosaurus femur measured 105 cm ( 41 in ) long . In several smaller specimens of Gorgosaurus , the tibia was longer than the femur , a proportion typical of fast @-@ running animals . The two bones were of equal length in the largest specimens . The long , heavy tail served as a counterweight to the head and torso and placed the center of gravity over the hips . 
