There are many kinds of dinosaurs, and their shapes are even more strange. Lei Long is a monster. Its body is heavier than six elephants. Every step it takes makes a loud noise like thunder. Liang Long's body is very long, more than 20 meters from beginning to end. He walks like a moving suspension bridge. Stegosaurus has two rows of triangular blades on its back and four sword-like tail spines on its tail. Triceratops has three big horns on its face, one above its nose and the other two above its eyes. Each corner is one meter long-this face is daunting to any animal.
Ichthyosaurs and pterosaurs are relatives of dinosaurs. Ichthyosaurs are very similar to dolphins today. It can dive into the water to find food. Pterosaurs have wings on both sides of their bodies. When it flies high, it looks like a light plane soaring in the sky.
Most dinosaurs ate plants, and some specialized in meat. Tyrannosaurus Rex is a very fierce carnivorous dinosaur. Its head is big, its body is short, and its teeth are like sharp daggers.
Dinosaurs laid eggs. The shell of a dinosaur egg is very hard. After the little dinosaur hatches, it will be carefully looked after by the big dinosaur until it can find its own food.
Dinosaurs have lived on the earth for more than 100 million years. About 65 million years ago, these dinosaurs suddenly disappeared mysteriously, and humans have not solved this mystery so far.
Thoughts on writing a composition on reading dinosaur fossils
I am curious about the name "dinosaur", but I feel a little scared after listening to it, because dinosaurs were very dangerous animals in ancient times.
Last Monday, Beijing Wenhua Media Company distributed a book to every student in Lixin Primary School. I was lucky enough to read the book The Mystery of Dinosaurs.
The content of this book is wonderful! There are the best dinosaurs here! Strange stories told by dinosaur fossils! Dinosaur family ... Before reading these, I had many questions about dinosaurs in my mind, such as what is the name of the largest dinosaur in the world? What about the longest and smartest dinosaur? How did the "dinosaur graveyard" come into being? How many kinds of dinosaurs are there in the dinosaur family? After reading The Mystery of Dinosaurs, I have a very deep understanding of dinosaurs. I know their living habits, their bodies, their living environment and why they are extinct.
I understand that the largest dinosaur is not Tyrannosaurus Rex, but is10cm longer than the king of Tyrannosaurus Rex. The longest dinosaur is Megalodon, and some of them are 3 1 1 m long! Tyrannosaurus rex hasn't appeared yet! The cleverest dinosaur is sawtooth dragon, which is called odontosaurus in Latin and is 2.4 meters long. It lived in the late Cretaceous, which is now Canada and the United States.
Sawtooth dragon has a large brain and developed sensory organs, similar to modern ostriches. Their eyes are unusually large and the distance between them is very wide. They have good cognitive ability and judgment, and they have strong stereoscopic vision.
The mystery of dinosaur extinction has puzzled scientists for centuries! There is no unified statement so far, and this mystery will continue. When our generation of primary school students grow up, go to archaeological proof! We should study scientific knowledge well from now on and make contributions to our country in the future! Dinosaurs abound, and there is a lot of knowledge worth exploring.
We should inspire ourselves with the spirit of exploration, study hard and work hard from now on to be qualified builders in the new century.
Watch the dinosaur exhibition and write 300 words.
On the morning of May 2, my mother and I went to the People's Park to watch the dinosaur exhibition and wrote 300 words.
As soon as we entered the park gate, we saw a sea of people, almost all of whom came to see the dinosaur exhibition.
I asked my mother, "How far is it from the dinosaur exhibition area?" Mom said, "Maybe it's just ahead.
"Sure enough, I walked a little further and saw a large clearing surrounded by inflatable walls. This is the exhibition area.
As soon as I entered this area, I was fascinated by all kinds of dinosaurs with different shapes, including Tyrannosaurus Rex, Triceratops, Pachysaurus, Allosaurus, Liang Long and Clatot. , the composition of the first grade of primary school, "Looking at the dinosaur exhibition composition 300 words".
Some of these dinosaurs lived in the early or late Jurassic and some in the early or late Cretaceous, which can be distinguished by the number of their toes. The more toes they have, the farther they live. On the contrary, the fewer toes, the closer they live.
I think these dinosaurs are particularly interesting. They taught me a lot about dinosaurs, so I reluctantly left the exhibition area after watching them for a long time.
Composition in the fifth grade Chinese book: How did my research report the extinction of dinosaurs?
In the Mesozoic era more than 200 million years ago, a large number of reptiles lived on land, so the Mesozoic era was also called the "reptile era", and the earth was widely occupied by vertebrates for the first time.
At that time, the earth's climate was warm and there were dense forests everywhere. Reptiles have enough food, and gradually flourish, with more and more kinds.
They constantly differentiate into various reptiles, some become turtles today, some become crocodiles today, some become snakes and lizards today, and some evolve into mammals all over the world today.
Dinosaurs are the largest reptiles. They are very suitable for living in swamps and shallow lakes. At that time, the air was warm and humid, and food was easy to find.
So dinosaurs ruled the earth for tens of millions of years, but for some reason, they suddenly became extinct in a short time 65 million years ago. Today, people only see a large number of dinosaur fossils left at that time.
People are still studying the reasons for the extinction of dinosaurs.
For a long time, the most authoritative view is that the extinction of dinosaurs was related to a big meteorite 65 million years ago.
According to research, an asteroid with a diameter of 7- 10 km once fell on the earth's surface, causing a big explosion, throwing a lot of dust into the atmosphere, forming dust fog that covered the sun, leading to the temporary suspension of plant photosynthesis and the extinction of dinosaurs.
The asteroid impact theory quickly gained the support of many scientists.
199 1 year, a meteorite impact crater was discovered in Yucatan Peninsula, Mexico, which further confirmed this view.
Today, this view seems to be conclusive.
However, many people are skeptical about this asteroid impact theory, because the fact is that frogs, crocodiles and many other temperature-sensitive animals survived the Cretaceous period.
This theory can't explain why only dinosaurs died.
So far, scientists have put forward more than a dozen hypotheses about the causes of dinosaur extinction, and the rich and dramatic "meteorite impact theory" is just one of them.
In addition to the "meteorite impact theory", the main viewpoints on dinosaur extinction are as follows: 1. Climate change theory.
65 million years ago, the earth's climate changed suddenly and the temperature plummeted, which led to the decrease of oxygen content in the atmosphere and dinosaurs could not survive.
Some people think that dinosaurs were cold-blooded, without hair and warm organs, unable to adapt to the decline of the earth's temperature, and all of them froze to death.
Second, the theory of species struggle.
At the end of the dinosaur era, the first small mammals appeared. These animals are rodent carnivores and may feed on dinosaur eggs.
Due to the lack of natural enemies, more and more small animals finally ate dinosaur eggs.
Third, the theory of continental drift.
Geological research has proved that there was only one continent on the earth when dinosaurs lived, and that was Pangea.
Due to the change of the crust, the Jurassic continent split and drifted, which eventually led to the change of environment and climate and the extinction of dinosaurs.
Fourth, the theory of geomagnetic variation.
Modern biology has proved that the death of some creatures is related to magnetic fields.
When the earth's magnetic field changes, creatures sensitive to the magnetic field may lead to extinction.
It can be inferred that the extinction of dinosaurs may be related to the change of the earth's magnetic field.
Five, angiosperm poisoning theory.
At the end of the dinosaur era, gymnosperms on the earth gradually became extinct, replaced by a large number of angiosperms, which contained toxins that gymnosperms did not have. Giant dinosaurs ate a lot, and a large number of angiosperms led to excessive accumulation of toxins in the body and finally poisoning.
Sixth, the theory of acid rain.
There may have been strong acid rain at the end of Cretaceous, which dissolved trace elements including strontium in the soil. Dinosaurs ingested strontium directly or indirectly through drinking water and food, which led to acute or chronic poisoning and eventually died in batches.
There are many hypotheses about the extinction of dinosaurs.
However, these hypotheses have more supporters in the scientific community.
Of course, each of the above statements has some imperfections.
For example, the "climate change theory" does not clarify the reasons for climate change.
After investigation, it was found that some small osteophytes in dinosaurs could compete with early small mammals, so there were loopholes in the theory of species struggle.
In modern geology, the "continental drift theory" itself is still a hypothesis.
"Angiosperm poisoning theory" and "acid rain theory" also lack sufficient evidence.
Therefore, the real reason for the extinction of dinosaurs remains to be further explored.
Write a composition about the dinosaur model.
I have two powerful dinosaur models.
My father bought it for me when I was in primary school.
One of them is Tyrannosaurus Rex, a giant dinosaur with fierce looks. It stands on its strong hind legs, its forelimbs are short on its chest, but its head is big and its eyes are bright enough to reveal its spirit! Tyrannosaurus rex has a big mouth, sharp teeth and many long teeth. It can swallow a baby in one bite.
It is so powerful that animals will run for their lives when they see it! And deinonychus, dinosaurs that lived in the Cretaceous period.
Tyrannosaurus rex is made of rubber. This monster is ten centimeters high and fifteen centimeters long. Its belly is dark yellow, each has its own characteristics, and it is very fierce! The back is green and the spine is purple.
Feet on the ground, front legs forward, claws sharp, mouth half open, showing sharp teeth.
Never bite when eating meat, just swallow it.
Clawing, it seems that he killed other small dinosaurs and leaned forward, or was chased by the enemy and fled for his life.
Deinonychus also landed on its feet, with its forelimbs up, its body smaller and its tail about five centimeters long.
Deinonychus has a knife-like claw on the second toe of each foot, which can give a fatal blow to its prey.
Whenever I finish my homework, I will play a dinosaur war with these two little dinosaurs.
The war has begun. Tyrannosaurus rex was strong, but not as smart as deinonychus.
Deinonychus always bypassed Tyrannosaurus Rex's attack.
But I love peace, so I make it up every time.
This precious dinosaur model, an artistic treasure, recorded the dinosaur era for a long time, fascinated modern people, and even I was impressed by the power of dinosaurs.
The huge dinosaur family will be brilliant forever! Tianjin Bao Tong Wealth Jewelry Wan Wen
Please indicate the source for reprinting. The topic of primary school students' composition is to find some information about dinosaurs, with 350 words.