As his group of researchers unearthed a dinosaur bone, a sudden nearby explosion caused the fragile bone to shatter. When they investigated, Dr. Piltdown and his team saw what they believed to be a dinosaur egg in perfect condition and shipped it off to the museum. Unbeknownst to them, however, the "dinosaur egg" was really a spacecraft piloted by Steggy, an alien Stegosaur from a world beyond.
Dr. Piltdown isn't seen again until the episode's climax. When he and the researchers happened upon Steggy, they set out to make him part of the research project.