Extinction

Two-hundred and thirty million years ago the first dinosaur-like creature roamed the earth. Within five million years it could be considered a dinosaur. They were soon at the top of the food chain. They populated every continent. Then 65 million years ago they vanished. The most powerful creatures ever to live on earth had become extinct.
Dinosaurs were not the only victims of this 'mass extinction.' There were many other species that were killed off. During what is known as the K-T extinction (K stands for Cretaceous, T stands for Tertiary), many species and families became extinct. These include all marine reptiles such as plesiosaurs, mosasaurs, ichthyosaurs, and ammonites, swimming and flying reptiles, sea crocodiles, and foraminifera. In addition to that there were many bony fish, sponges, snails, clams, and sea urchins became extinct.
Paleontologists have proposed scenarios that could have caused these extinctions. One such scenario involves the growing number of small mammals which ate dinosaur eggs, and therefore caused the dinosaurs' birth rate to drop. …