An introductory page contains a diagram of the Mesozoic Era showing the Triassic, the Jurassic, and the Cretaceous Periods. A brief text explains that living things have been around for billions of years and the place in time for the Triceratops. A twenty-four page story follows which personifies a male Triceratops and takes him through a day in his life. After eating some nearby plants, he observes two Pachycephalosaurus fighting over territory by crashing their heads together. He continues wandering and eating before discovering he has become separated from his herd.