That is to say, 650,000 years ago, an asteroid with a diameter of about 15 km crashed into southern Mexico at a speed of 2 km per second, and then an earthquake with a magnitude of 1 1 was triggered in America. The tsunami triggered by the earthquake was nearly 3 meters high and swept the whole earth. In addition, the burning of gypsum in the stratum of Mexico produces a large number of sulfides, and black smoke and gravel cover the whole earth, blocking the sunlight, and all green plants are extinct. After that, the earth became dark and cold, and acid rain continued. This situation lasted for three years, resulting in the extinction of 7% of the earth's creatures, which is the fifth mass extinction in the history of the earth.