2. What is the evidence given by scientists to support that an asteroid caused mass extinction of plant and animal life ?

The evidence for the asteroid caused mass extinction of plant and animal life, came in 1992 when scientist in Mexico uncovered an under ground crater 175 km wide, which turned out to be exactly 65 millions years old. The crater was probably caused by an asteroid 10 km in diameter hitting the earth at thousands of miles an hour, with the force of 70 million one megaton bomb.