The large plant-eaters such as Apatosaurus moved constantly, perhaps like elephants feeding almost around the clock. They probably destroyed plant life as they grazed through an area, but at the same time they opened the ground to more sunlight for new growth. Migration of the sauropods was random and only loosely tied to a region. They may have had separate areas for laying eggs, where the young would hatch away from the adults. The large herds probably were mostly adults, with the adults protecting the young.
The large sauropods browsed at the tops of trees for food, where no other dinosaurs could reach. The smaller plant-eaters ate ground cover and shorter brush. Some, such as Stegoceres, probably reared up on their hind legs to get higher brush. The small meat-eaters probably ate lizards and scavenged meals from other animals. Large meat-eaters would have eaten smaller dinosaurs and even attempted to kill a sauropod, perhaps a youngster that strayed from the herd.
Dinosaurs of the Late Jurassic in China showed general similarities of body to those in other parts of the world. There were sauropods, stegosaurs, carnosaurs, and coelurosaurs, but when we look carefully, we see that the Chinese forms were all unique. They were not found in Africa or North America. China seems to have been isolated from the rest of the world at this time.
Archaeopteryx flew from conifer tree to conifer tree. It was an ancestor of modern birds. A coelurosaur dinosaur of the Middle Jurassic may have been its ancestor.
More and more kinds of dinosaurs were evolving in the Middle and Late Jurassic Period, but the most important dinosaurs of this time were the sauropods. These immense creatures roamed the earth searching for food to sustain their enormous size. The earth did provide for them, though there are still some questions scientists have about their diets. These animals were the most successful dinosaurs, with their numbers growing rapidly. They were truly the masters of their universe.