1. The Extinction of the Dinosaur

2. Dinosaurs came in many shapes and sizes.

3. Then, about 65 million years ago, these huge reptiles died.
Over the years scientists have developed many theories to explain the causes of the disappearance of the dinosaurs.

4. The theories Disease. The Earth’s collision with a large asteroid.
A change in the Earth’s climate.
Disease.
The Earth’s collision with a large asteroid.

5. A change in the Earth’s climate.
During the Cretaceous period the climate was tropical all over the world.
At the end of the Cretaceous period temperatures dropped and the climate became much colder.
For this reason, many of the plants that the plant eating dinosaurs ate died. With no food these huge beasts died.

6. Disease
As the Cretaceous period went on, more and more land bridges started to appear on the Earth.
Some scientists think that diseases killed off the dinosaurs when large groups migrated across land bridges between continents and infected one another with new illnesses.

7. The Earth’s collision with a large asteroid
Scientist suggested that about 65 million years ago, the Earth was struck by a huge asteroid
The explosion caused billions of tons of dust. The cloud of dust blocked the sunlight. The plants were not able to make food, and they died. Therefore, the lack of plants killed the plant eating dinosaurs which then caused the death of the meat eating dinosaurs.

8. Conclusion
It seems that no one theory explains why the dinosaurs died out. Perhaps dinosaurs simply could not adjust to changes that were taking place on the Earth towards the end of the Cretaceous period. Perhaps it was a combination of causes that contributed to the end of the Age of Dinosaurs.