Some scientists believe that 65 million years ago an asteroid struck what is now the Yucatan Peninsula, thereby causing extinction of the dinosaurs  These scientists have established that such a strike could have hurled enough debris into the atmosphere to block sunlight and cool the atmosphere  Without adequate sunlight, food sources for herbivorous dinosaurs would have disappeared, and no dinosaurs could have survived a prolonged period of low temperatures
These same scientists, however, have also established that most debris launched by the asteroid would have settled to the ground within six months, too soon for the plants to disappear or the dinosaurs to freeze
Dinosaurs were susceptible to fatal respiratory problems caused by contamination of the air by asteroid debris.