Their theory was hotly disputed. Now the irrefutable evidence is rolling in. Martin Belderson's dramatic film retraces the hunt for evidence for the hidden 'smoking cannon': the crater left by the impact 65 million years ago. In 1991 it was found, buried beneath the coastline of the Yucatan Peninsula, Mexico. The central crater is at least 180km wide and nearly 20km deep. The outer impact rings may stretch to 300km in diameter, making it the largest crater produced in the inner solar system in the last four billion years. But did it cause extinction?
The fossil record seemed to show a gradual decline and extinction of animals like the dinosaur before the line of the impact. The in-fighting forced many scientists to re-examine their fossil beds. What they discovered has overturned the orthodoxy and led to a new understanding of how extinction works, and why some species survived whilst others vanished. Alvarez, father and son, have finally been vindicated.