As the number of carnivores in a community increases, they eat more and more of the herbivores, decreasing the herbivore population. It then becomes harder and harder for the carnivores to find herbivores to eat, and the population of carnivores decreases. In this way, the carnivores and herbivores stay in a relatively stable equilibrium, each limiting the others population. A similar equilibrium exists between plants and plant-eaters. Some also have flat teeth for grinding tough plant fibers.
Many herbivores have cheek pouches in which they can store food for a while.
Plant-eaters also usually have larger digestive systems that are needed to digest the tough fibers. Fossilized stomach remains are extremely rare, and coprolites are hard to match up to a particular dinosaur. Flowering plants evolved during the Cretaceous period. Carnivorous dinosaurs usually had long, strong legs so thay they could run fast in order to catch their prey. They also needed big, strong jaws, sharp teeth and deadly claws that could kill and then tear apart the prey.