The numerous prehistoric creatures inhabiting Skull Island were brought to life through the use of stop-motion animation by Willis O'Brien and his assistant animator, Buzz Gibson. The stop-motion animation scenes were painstaking and difficult to achieve and complete after the special effects crew realized that they could not stop, because it would make the movements of the creatures seem inconsistent and the lighting would not have the same intensity over the many days it took to fully animate a finished sequence. A device called the surface gauge was used in order to keep track of the stop-motion animation performance. The iconic fight between Kong and the "Tyrannosaurus" took seven weeks to be completed. O'Brien's protégé, Ray Harryhausen, who later worked with him on several films, stated that O'Brien's second wife noticed that there was so much of her husband in Kong.