What caused the death of the dinosaurs approximately 66 million years ago? You may think that you know, but a new study in the Proceedings of the National Academy of Sciences now states that volcanic activity — not asteroid impacts — probably drove their disappearance, as well as most other mass extinctions in our planet’s past.
Making A Mass Extinction
Species extinctions are a normal part of the process of evolution, but they sometimes become so numerous and so sudden that they transform into what scientists call a "mass extinction event."
These events take place whenever approximately 75 percent of the world’s existing species disappear within two to three million years or less. Thus far, there have already been five such extinctions. The death of the dinosaurs was the most famous and most recent at the boundary between the Cretaceous and the Tertiary periods.
