The Diplodos first appeared in 1987 and ran for one season of twenty four episodes (although it has been repeated since). It focuses on five dinosaur-like creatures, known as the diplodorians. These creatures are from Diplodorianrex, the sister planet/parallel of Earth, which lies in the fourth dimension – meaning whatever happens to one planet also affects the other planet.

The Diplodos have successfully defended their home planet and put up a strong defensive shield. This results in the Diplidos’ enemies, led by the evil Santos, targeting Earth in order to destroy the Diplodos’ home planet. With this threat, the five chosen Diplodos travel to Earth in order to defend the planet, which will result in saving their own. Here, they meet and become allies with two children, Peter and Joan.