Extinction of Dinosaurs

             Dinosaurs are wonder to both adults and children. It is hard to imagine that such a large creature roamed on earth once upon a time. They were most successful creatures than any other group of animals and mammals. They ruled our planet for about 150 million years. They are probably giant killing machines. But 65 million years ago they suddenly disappeared from the earth. What had actually happened at that time? Did the dinosaurs face terrible catastrophic conditions on earth? It is one of the great mysteries of paleontology.

             The mystery beyond this question increased when scientific researches revealed a fact that the dinosaurs were adapted to their environment and apparently had worldwide distribution. Their traces were found in every continent including Antarctica and some isolated oceanic islands.

             Scientists started extensive research in this aspect. They obtained geological evidences which holds clues and led to many hypothesis. But still there are many unanswered questions like what is the process of extinction and how long does it take. There are several theories put forth by many scientists. Some of the important theories are

1)     
Asteroid impact theory:

  This theory proposes that a large asteroid of about 10 km diameter wide entered into earth’s atmosphere. At that time this incident was very sudden and would not be prevented. It crashed on the surface of earth. At first 50 percent of all the creatures and dinosaurs died then. Due to the impact of the asteroid the sky around earth was blanketed by smoke and dust for many years. This layer did not allow sun rays. Because of lack of sunlight plants and greenery of earth started reducing. Due to this herbivorous dinosaurs began to die which consequently led to the extinction of carnivorous dinosaurs.

 

2)      Multiple impact theory:

Some scientists proposed that small meteorites had entered earth’s atmosphere and aroused multiple impact on its surface. The damage caused by the impact of multiple meteorites is equal to the damage caused by the impact of asteroid and the result is same.

 3) Volcanic eruptions:

Another theory explains that there is large number of volcanic eruptions on the earth at that time. They increase the temperature on earth and poisonous gases are released. The level of oxygen also dropped. As dinosaurs are very huge they need very large amount of oxygen for their respiratory system. This theory proposes that large dinosaurs died due to lack of oxygen and the very small dinosaurs which had survived evolved to birds further.

4)      Floods and natural calamities:

Here in this theory it was proposed that there were floods and natural      calamities like large tsunamis, hurricanes etc. Even unable to face these calamities dinosaurs might have died.

5)      Diseases:

Some theories say that dinosaurs might have faced several fatal diseases at that time like cancer. They may have got nutritional problem. Because of some poisonous plants the herbivorous died which consequently led to the death of carnivores.Along with these theories many others were proposed. But none of them was approved as a perfect answer to the question of extinction of dinosaurs.

Whatever might havehappened was good for us because if they still ruled our planet humans and many other creatures might not have evolved.

-Article by Prathiba