The exact cause of the Cretaceous-Tertiary extinction event are unknown, though several theories exist. The most popular of these is that a meteor struck the Earth around the area of what is now the Gulf of Mexico, which sent up huge clouds of dust and other debris which blotted out the sun, causing many forms of life to die out. Another theory is that volcanic activity may have spiked at the end of the Cretaceous, also blotting out the sun.
