As an animator myself I've been a fan of Jim's work since I was a kid. When Dinosaurs Ruled The Earth is a masterpiece. I watched the super-8mm reels bought from the back of Famous Monsters over and over. I was thrilled to chat with Jim on a couple of occasions. What a masterful artist and master of the craft.
He painted Jack frame by frame on pieces of glass. He and Phil Kellison came up with what they called, “The animated glass shot.” It was also used where Jack knocks the sand bucket into the giant’s eyes. Painted on glass frame by frame during the stop-motion. Must’ve taken forever.