For over 150 million years, dinosaurs were the dominant animals on the planet. Then, about 65 million years ago, toward the end of the Cretaceous period, they became extinct.
There are many theories about why dinosaurs became extinct. Climate change, geological events, change in vegetation and diseases are some of the factors may have contributed the extinction of the dinosaurs .
Theories about dinosaur extinction
Of late scientists have held heated debates on the reasons for this extinction, which was the second highest in the entire history of the Earth. They have proposed more than a hundred theories to explain the sudden disappearance of these animals, but many of them have been discredited over time.
Asteroid impact
The most accepted theory talks about the impact of a large asteroid or comet on earth at Chicxulub in the Yucatan Peninsula in Mexico that might have caused the dinosaurs to become extinct. The impact could have caused massive damage, including a giant cloud of dust spreading iridium throughout the land.
This led to major changes in climate destroying several forms of plant life. Herbivorous dinosaurs might have died of hunger and carnivores were left with nothing to eat as well.
This theory stems from the discovery that a layer of rock which dates precisely to the time of extinction is rich in deadly iridium.
This theory makes sense but has a problem: The scientists and paleontologists have not yet managed to find skeletons and dinosaur fossils that date from the time of impact.
Competition from Mammals
Some scientists suggest that the dinosaurs became extinct because mammals stole and ate all the eggs of dinosaurs. But this theory is unsupported because marine mammals were non-existent at the end of the Cretaceous period.
Disease
As a result of the shifting of continents towards the end of the Cretaceous period, new routes opened up between places such as Asia and North America, allowing dinosaurs to migrate areas previously inaccessible to them. It is possible that dinosaurs were wiped out by a disease to which they were non resistant. However, this hypothesis is unable to explain the sudden disappearance of other species at the time.
Theory of Ice Age
Throughout its history Earth has witnessed Ice Ages. Since dinosaurs were thought to be cold-blooded, it would have been very difficult for them to come in terms with such cold conditions. However there has been no evidence of any occurrence of ice age during the life of the dinosaurs.
Theory of Volcanoes
It is said that 65 million years ago the Deccan Plateau in western India witnessed severe volcanic eruptions which cast a huge amount of dust and debris into the atmosphere, enough to prevent the sun’s rays coming to earth for a long period of time. This caused huge change in climate and the dinosaurs found it very difficult to adapt to this situation.
The Gradual Extinction
Until recently it was thought that dinosaurs had gradually disappeared at the end of the Cretaceous period. According to this school of thought, dinosaurs slowly and gradually became extinct.
Finally
The last dinosaurs that walked on the earth died about 65 million years ago. Extinction of the dinosaurs is a great mystery. When the dinosaurs became extinct, many species like crocodiles managed to survive. Scientists will continue to produce theories about this great extinction.
