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Dinosaurs dying at the end of the Cretaceous Period. Volcanism is thought to be one of the main causes of the dinosaurs dying out.
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K-T Extinction (Why Did the Dinosaurs Go Extinct?)

Why did the dinosaurs go extinct? No one knows for sure, and scientists have come up with a number of theories to explain why the dinosaurs suddenly died out about 65 million years ago. This extinction event is known as the the Cretaceous-Tertiary Mass Extinction or the K-T Extinction, and it wasn't just the dinosaurs that went extinct--roughly two thirds of all of the plant and animal species on Earth disappeared.

Scientific evidence shows us that at the time the dinosaurs died out, the Earth experienced an increase in volcanic activity, and was also struck several times by asteroids or comets. Most scientists believe that these things could have affected the Earth in ways that would have it made it very hard for the dinosaurs to survive.

Increased volcanic activity may have thrown dust into the atmosphere, blocking sunlight and causing a drop in photosynthesis (and plant growth). This would have weakened the Earth’s ability to support the ecosystems that thrived in the Cretaceous Period. The same thing could have happened when one or more large asteroids impacted the Earth, and the combination of volcanoes and asteroid impacts may have poisoned the Earth’s atmosphere for years, making plant and plankton growth impossible and fatally disrupting food chains worldwide.

Other things might have helped cause the dinosaurs’ extinction. For instance, during the Cretaceous Period, we know that the oxygen levels in the Earth’s atmosphere were much higher than today. This means that when a large asteroid impacted the Earth, there could have been large firestorms, which would have caused a temporarily increased greenhouse effect that could have killed off a large number of organisms. There is also scientific evidence that the Earth’s sea levels dropped significantly during the K-T boundary, and although no one knows exactly what caused this, it could have caused widespread climate changes that might have made it very hard for the dinosaurs to survive.

No one knows for sure why the dinosaurs died out, and there are many scientists around the world still conducting research in order to test different theories and answer this question.

Last modified March 25, 2010 by Jennifer Bergman.

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