Scientists are researching which plants giant dinosaurs could have lived off more than 100 million years ago. They want to find out how the dinosaurs were able to become as large as they did. In actual fact such gigantic animals should not have existed. There is a law to which most animals living today conform: The larger an animal, the smaller the density of the population, i.e. the fewer animals of the same species there are per square mile. The larger an animal is, the larger the amount of food it has to have in order to survive. Therefore a specific area can only feed a certain maximum number of animals.