英语作文:恐龙灭绝的原因

The extinction of dinosaurs
The mystery of dinosaur extinction
More than 200,000,000 years ago in the Mesozoic,a large number of reptiles living on land,it is also known as the Mesozoic "era of reptiles," the earth was the first to occupy a wide range of vertebrates.At that time the Earth's climate was warmer,all over the dense forests,reptiles have enough food,gradually prospered,more and more species.They continued to differentiate into a variety of different types of reptiles,some of today has become a turtle,and some turned into the type of crocodile,and some turned into today's snakes and lizards,which are a class of Around the world and evolved into today's mammals.
All is the dinosaur reptiles in the largest class of physical,very suitable for living in the marshes and shallow lake,when warm,humid air,food is also very easy to find.Therefore,dinosaurs ruled the earth for several million years of time,but I do not know why,in their 6500 years ago a very short period of time of the extinction of a sudden,people see only the left by that time a large number of dinosaur fossils.
With regard to the reasons for the extinction of dinosaurs,it is still being studied.For a long time,the most authoritative view,and the extinction of the dinosaurs 6500 years ago about a large meteorite.According to the study,there was a 7-10 km in diameter asteroid will fall on the earth's surface,causing a large explosion,such as throwing a lot of dust in the atmosphere to form the Zhetianbiri House of Sand and Fog,led to the suspension of plant photosynthesis ,And therefore the extinction of the dinosaurs.