One of the theories is the falling of asteroids. These rarely enter the earth's atmosphere, but it is believed that it hit the Yucatan Peninsula in the Gulf of Mexico. It caused a natural disaster that made some dinosaurs completely extinct. This huge asteroid was believed to be about 4 -9 miles wide in size when it struck the earth, causing a fatal blow that sent dust and steam into the atmosphere. This triggered huge forest fires, tidal waves, severe storms, and eliminated sunlight for 6 months. Even the strongest dinosaurs like Tyrannosaurus rex could not live through this disaster.