The answer to this is unknown.

Although there are quite a few hypotheses, and the hypothesis of an asteroid hitting the Yucatan Peninsula in Mexico has been accepted by many people. However, there is still a lot to be known.

Continuing to the front exhibition hall, there are some animals that are older than the age of dinosaurs in the small real discovery fossil exhibition.

Among these animals are also large animals with vertebral columns, and among them are also common ancestors of mammals and reptiles.

It turns out that the widely praised mass extinction of dinosaurs was not the worst mass extinction event.

Going back another 200 million years, the prolonged and sustained eruption of the huge Siberian Shield volcano caused the extinction of most life on Earth.

And this was preceded by two horrific mass extinctions.

Looking at the huge and ferocious dun's fish and the fossils of ammonites and trilobites, Xiao Zhen's heart no longer knows what it feels like.

Countless species are like passers-by, leaving slight traces on the earth's crust and then disappearing without a trace.

It seems that only Nautilus has escaped in this long knockout round.

However, the nautilus is no longer the protagonist on the planet. You know, in its heyday, the size of the nautilus could reach several meters.

However, when it comes to algae and sponges that have been living in the long river of life, Xiao Zhen seems to have little interest. It seems that these two are too common and too mundane.

After another period of time, Lao Wu patted Xiao Zhen's forehead and said, "Okay, it's almost time, I'm ready to go home for dinner." ”

Xiao Zhen said, "No, I still want to see it." ”

So, Lao Wu continued to let Xiao Zhen review the entire fossils on display, whether it was a trilobite or a Tyrannosaurus rex, Xiao Zhen carefully looked at it again.

Just when Xiao Zhen looked at the Chinese dragon bird again, the staff was ready to turn off the lights and get off work.

So, Xiao Zhen had no choice but to follow Lao Wu out of the museum, get on the No. 666 bus again, and embark on the way home.

Along the way, Xiao Zhen kept asking: "Dad, why did only the nautilus survive among so many animals?" ”

"Haha, I can't answer this question, after all, this is hundreds of millions of years of rain and wind, and the vicissitudes of life. And a lot of other animals have actually evolved. Lao Wu thought about it and said.

Lao Wu continued, "There is no need to continue asking, I can hardly answer these questions. ”

So, Xiao Zhen stayed quietly aside.

When I got home and finished dinner, Xiao Zhen still couldn't calm down for a long time.

The exams at Huaxiong Middle School were completely left behind by Xiao Zhen, who began to look for some knowledge of dinosaurs and paleontology in books such as "One Hundred Thousand Whys".

However, in the end, Xiao Zhen found that flipping books could not solve any problems.

In the end, in the "Xinhua Dictionary" and the "Modern Chinese Dictionary", Xiao Zhen found some terms from these paleontological eras.

Unable to learn more about these contents, Xiao Zhen worked blindly for two hours and put them aside.

For the rest of the weekend, Xiao Zhen recalled the knowledge points encountered in the Huaxiong Middle School exam, and opened the 24 textbooks of Chinese and mathematics for comparison.

When he came to school, Xiao Zhen found that everyone was looking for those classmates with mobile phones to check their scores.

So, Xiao Zhen also got to line up next to a classmate with a mobile phone.

However, by the time the phone was handed to Xiao Zhen, the small battery on the interface of this phone was already empty.

So, just halfway through the call, the phone automatically turned off.

After returning the phone to this classmate, Xiao Zhen walked to another classmate who had a mobile phone.

However, his mobile phone has been shut down by continuous score checks.

So, Xiao Zhen had no choice but to go to the last classmate with a mobile phone, Xiao Yang.

"Yo, Wu Zhenzhen, what kind of wind blew you here today. Xiao Yangpi said with a smile.

"Isn't this, isn't it here to 'borrow the east wind'?" Xiao Zhen thought for a while and said with a smile.

"Okay, tell me your test number, and I'll check it for you. Xiao Yang said with a smile.

After a minute, Xiao Yang said: "140 points, two points short of the 142-point line." ”

"Are you sure?, I'm basically right about math?" Xiao Zhen said, touching his head.

"Then can you guarantee that the Chinese composition is not off-topic? Isn't it only 50 points when you get a zero score in the essay?" Xiao Yang said with a smile.

So, Xiao Zhen returned to his seat dejectedly.

Looking at the dejected little truth, Xiao Yang looked very happy.

However, this kind of thing is not paper-wrapped in the fire after all.

The more I think about it, the more wrong it is, no matter how much this language is, the composition will not be so biased!

So, when I got home at noon, the real mother and Xiao Zhen checked the results together, and a voice came from the phone saying that it was 170 points, and if you sign up today, you can reduce the tuition fee by 1000.

"What's the matter? The classmate checked for me in the morning and didn't cross the line?" Xiao Zhen didn't pay much attention to what was said on the other end of the phone, and looked at the real mother and said.

"Haha, I guess it's bluffing you, you probably did something sorry for him. The real mom said with a smile.

The person on the other end of the phone saw that no one was paying attention, so he hung up the phone.

"How about it, why don't you go to Huaxiong Middle School to study?" said the real mother happily when she heard the 1,000 tuition reduction.

"It's too far, isn't it?

"Your dad said that the cafeteria is okay, there are chicken legs and vegetables, and the nutrition is sufficient, what's wrong with boarding school?" said the real mother.

"I don't want to go to boarding. Xiao Zhen said.

"You have to know that your aunt has been boarding since the first year of junior high school. The real mom continued.

"Isn't there still Blue Sky Middle School that hasn't been examined? Blue Sky Middle School is only a 10-minute walk from home, isn't it much better than those schools?" Xiao Zhen said.

The real mother excitedly: "Isn't this afraid that you won't be able to pass the test?"

"Why? Have faith in me. Xiao Zhen clenched his little fist and said confidently.

"Okay, then you can review it well, don't take a pile of books like you did the night when you finished the Huaxiong Middle School exam before. Real Mom said.

"It's called a thirst for knowledge. Xiao Zhen said unconvinced.

"Hey, you're still thirsty for knowledge, so what are you asking for?" said the real mother.

"Okay, let's start with a simple one, how did this dinosaur go extinct?" asked Xiao Zhen.

"Forget about this simple question, change it to a difficult one. The real mother thought about it and said.

"Okay, then it's difficult, how did the birds come about?" asked Xiao Zhen with a smile.

"It's coming out of the egg. The real mother said perfunctorily.

"That's not what it means, how did the first bird come about. It's not about how the bird was born. Xiao Zhen thought about it and added.

That's a really hard question to answer. The real mother thought about it and said.

"Haha, so let's do it, do you want to know if you're thirsty?" Xiao Zhen said with a smile.

"That's not what it means, it's useless if you know all this knowledge? What's the use of knowing how dinosaurs went extinct? What's the use of knowing where birds come from?" said the real mother after thinking about it.

"Well, I don't know what's the use for the time being. Xiao Zhen thought about it and said.

"So, although these things are some difficult problems, but they are not what you should get now, now review well, and be admitted to Lantian Middle School, Tenglong Middle School is the key. Real Mom said.

"Okay, be taught. Xiao Zhen suddenly realized.