 Soon after describing Stegosaurus , Marsh noted a large canal in the hip region of the spinal cord , which could have accommodated a structure up to 20 times larger than the famously small brain . This has led to the influential idea that dinosaurs like Stegosaurus had a " second brain " in the tail , which may have been responsible for controlling reflexes in the rear portion of the body . This " brain " might have given a Stegosaurus a temporary boost when it was under threat from predators . More recently discussed , this space ( also found in sauropods ) may have been the location of a glycogen body , a structure in living birds whose function is not definitely known , but which is postulated to facilitate the supply of glycogen to the animal 's nervous system . 
