The beginning of the end for the kings
The dinosaurs had several extinction phases, with the gigantic dinosaurs, being replaced by smaller, low browsing, beaked dinosaurs at the end of the Jurassic and early Cretaceous. Again, another extinction occurred and marked the late Cretaceous period. These dinosaur extinctions may have been related to the radiation of angiosperm plants (viz plants possessing flowers) which attracted animals to disseminate their pollen and seeds. A new generation of low browsing dinosaurs may have promoted the spread of these plants. Overgrazing by dinosaurs may have threatened many low-growing plants with extinction, except for the angiosperms which possessed reproductive superiority. The late Cretaceous period witnessed the Hadrosaurs or duckbill dinosaurs (Anatosaurus, Lambeosaurus, Corythosaurus and Parasaurolophus) occupying swamps and forests and large herds of Triceratops and their relatives on the grass plains together with Tyrannosaurus rex.