Each entry in Ancient Creatures includes key information either in chart or picture form that lists the name, pronunciation, and its meaning, as well as scientific classification, location of the fossil on a map of the world, estimated size in comparison to an average human, and the time period in which the animal existed. Extensive explanations of each animal follow, and include a detailed introduction, classification, anatomy, reproduction and population, intelligence, diet, behavior, habitat and other life forms, research, bibliography on relevant sources, websites for further research, and a vocabulary chart of pertinent words.