How Did Dinosaurs Become Extinct?

How did dinosaurs become extinct? Why aren't dinosaurs roaming the Earth with us today? No one really knows the answer to these questions, but you can explain the theories currently used to explain the end of the Dinosaur Age. To make these explanations even more exciting, consider taking a trip to your local children's museum to look at reconstructed dinosaur skeletons. Seeing life-sized reconstructions of these amazing creatures will help your child grasp the significance of this extinction.

The following theories are believed to explain why dinosaurs became extinct:

• An Asteroid Crashed Into the Earth: One of the most popular theories behind the extinction of dinosaurs is the idea that a giant asteroid crashed into the planet. This threw a huge cloud of dust and sulphur into the air, blocking sunlight and causing plants to die off. The dinosaurs died of starvation and cold temperatures that accompanied this constant winter. A thin layer of sediment found in rocks in many parts of the world is believed to be evidence of the dust cloud that blocked out the sun.
• Ice Age: Another theory is that the dinosaurs died during a global ice age. The Earth has gone through many ice ages and climate changes over time. During these periods, temperatures drop and glaciers move over the land. Colder temperatures and droughts may have killed plant life and dinosaurs.
• Disease: Some scientists believe a plague or disease is the root cause of the extinction of dinosaurs. When scientists observe pandemics today, they are reminded of the fact that other creatures once inhabited the Earth that are no longer here. A widespread disease could have wiped out all the dinosaurs if they had no natural defense or immunity.
• Volcanic Activity: Scientific evidence shows that there was a great deal of volcanic activity around the time dinosaurs become extinct. Too much volcanic activity could have sent up tremendous amounts of volcanic ash into the atmosphere. This would block out the sun's rays, reducing the temperature on the Earth's surface and causing the vegetation to die. Dinosaurs would not have survived thes changes in climate and food availability.

There is more than one mass extinction of dinosaur life. Major extinctions signaled the end of the Triassic and Cretaceous periods; a smaller-scale extinction ended the Jurassic Period. One of the big questions that continues to baffle researchers is why some animals, such as dragonflies, crocodiles and the Coelocanth, survived these extinction events.