Dinosaur extinction Theories research paper

The Cause of the Mass Extinction in the Late Cretaceous Period Dinosaurs first appeared around 245 million years ago, and they lived for 180 million years. Then suddenly, 65 million years ago they went extinct. Not only did all the dinosaurs die out, but also up "to 75% of all marine genera were lost" ("mass extinction"). This leaves scientists wondering about what could have led to this mass extinction in the Cretaceous Period. They have collected evidence from fossils and earth’s geography, to propose some theories Scientists believe that the dinosaur extinction was due to either the collision of a massive asteroid, the eruptions of the Deccan Trap volcanos, or the epidemic of diseases. The collision of a massive asteroid is believed to be have instigated the dinosaur elimination. First of all an asteroid is a "minor planet, small body orbiting the sun" ("asteroid”) .There are many asteroids in space. Scientists believe that earth was hit by an asteroid that was over six miles wide, or that earth was hit by a comet travelling 18 miles per second. They contemplate that when the asteroid hit earth’s surface, a great amount of debris and sulfur rose into the air. They believe that this blocked the suns light from hitting the earth. In result, all the dinosaurs and 70 percent of all animals and plants died (“What Killed the Dinosaurs").

Scientists have backed up their theory that earth was hit by an asteroid, with a great amount of evidence. In 1980, Walter Alvarez of the University of California at Berkeley discovered deposits of iridium in sediments that dated back from the Cretaceous period, which was when the mass extinction occurred. "Iridium is rare on earth, but is concentrated in meteors and comets" ("mass extinction").This led to proposal of the asteroid theory since the discovery of the iridium sediments proves that an asteroid had hit earth. Then in 1991, the Chicxulub crater was found on the Yucatan peninsula in Mexico. This crater was 112