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 …showed first 75 words of 2061 total…

…showed last 75 words of 2061 total…block out light and heat from the sun. This could have lasted for decades. This cloud of darkness would have killed off vegetation, and then herbivores, having nothing to eat, would have died. With no herbivores to eat, carnivores would have killed each other, and the reign of the dinosaurs would have ended. Now Alvarez's theory is regarded as one of the leading theories justifying the K-T extinct                                                               Biology 6th Period Dinosaur Report                                                               Ryan Humphries