The Hunt for a Culprit
What happened to cause such widespread devastation 65 million years ago? Scientists agree that species go extinct primarily as a result of changes in their environment. The extinction of many species around the world at one time reflects large-scale changes in the global environment.
To explain what caused this mass extinction, scientists have focused on events that would have altered our planet's climate in dramatic, powerful ways. The leading theory is that a huge asteroid or comet slammed into Earth 65 million years ago, blocking sunlight, changing the climate and setting off global wildfires. In recent years, however, researchers have also been investigating whether other forces, including massive volcanic eruptions and changes in sea level, may have contributed to the general environmental decline.