There are many theories about why the dinosaurs vanished from the planet. One theory is that a gigantic meteorite smashed into the Earth. Scientists believe that the meteorite was very big. The impact may have produced a large dust cloud that covered the Earth for many years. The dust cloud may have caused plants to not receive sunlight. The large plant eaters, or herbivores, may have died off, followed by the large meat eaters, or carnivores. This theory may or may not be true, but it is one explanation on why these giant reptiles no longer inhabit the Earth.