How did the dinosaurs become extinct? What happened so long ago to kill the "terrible lizard" a species that once roamed this earth? The answer is that no one knows for sure, but everyone seems to have their own favorite theory.
Some of the theories that led to the dinosaurs becoming extinct are:
A huge asteroid approximately 4-9 miles wide, struck the earth on the tip of the Yucatan Peninsula, in the Gulf of Mexico dealing the dinosaurs a fatal blow. This is one of the most popular theories. Upon striking, the asteroid would have caused huge forest fires, tidal waves, severe storms, and eliminated all sunlight for up to 6 months. The lack of sunlight and plant life would have killed the dinosaurs.
Another Theory is that the tropical climate changed. Scientists know that the climate was tropical back then because nearly half of the plants were tropical plants. The theory is that at the end of the Cretaceous period the temperature dropped. If that is the case the plant eaters would have surely died for lack of food. If the plant eaters died then the meat eaters food supply would be gone and they would eventually die out also.
Could volcanic eruptions have caused the death of the dinosaurs ? It is possible. When volcano's erupt, they send clouds of dust, sulfuric acid, and poisonous gases into the air making it impossible to breath . The dust and ash in the atmosphere would change the climate and sunlight levels too. Also, the ground would be covered with layers and layers of molten rock. The dinosaurs would never have survived such a hostile environment, if several volcano's erupted.
Some other theories include:
The dry climate became too dry, making the earth too much like a desert for the dinosaurs, mass flooding destroyed the dinosaurs, overpopulation of the dinosaurs could have resulted in competition and rivalry for food and therefore creating extinction.
The list of theories goes on and on. Since scientists did not live in that era they can not exactly pinpoint when the dinosaurs walked the earth or when they all died. It is also hard to pinpoint a cause for their extinction.