<h1 class= "pgc-h-arrow-right" > the outside world</h1>
"You've been through a lot from starting with a small single-celled organism in an undersea hot spring billions of years ago to having your own ocean.
Now, start your greatest exploration now!
From early terrestrial life to vast stars."
Book picked up:
As mentioned yesterday, this old ancestor named Fishstone Salamander could not continue to mix under the water and wanted to go to the land to beg for food.
What was on land at this time? The Great Desert empty? If you leave your hometown, you don't even have a well in your hometown, so why not?
At that time, there were still living things on the land.
The earliest group of seaweeds, some of which turned into moss on land, later evolved into plants.
Later, after our ancestors turned over to serfs and sang, chasing shrimp everywhere to eat, many shrimp were forced to run to fresh water and land to beg for a living. They are insects.
See? Nothing but these guys! Nothing but food!
On this day, a small bug was listening to her mother tell a story:
"Once upon a time, my mother's mother's mother... Her mother is still a small shrimp in the sea. At that time, there was a big devil in the sea, called Deng's Fish, who ate shrimp everywhere and scared shrimp to death. There are also many little devil kings, all of whom are fish and shrimp eaters."
"Wow! It's scary shrimp!'
"Yes! At that time, the mother's mother's mother's mother... The mother, who was chased by the fish at that time, six gods and no masters, seven tricks, bled eight immortals across the sea and died nine times, and finally ran to the shore. What's next..."'
"Ma Ma! Are you talking about fish like this?'
As soon as the mother worm turned back, she saw the goods behind her.
"How did you tm keep up!!!?"
There is no more below...
The fish wanted to go ashore, but they still made some preparations.
Their original even fins grew limbs and began to move on the shoals.
To adapt to the dryness of the air, they evolved their lungs and even learned to breathe with their skin. Since then, they have become a new species of ship - amphibians.
However, some of their behaviors are still not able to be carried out outside the water, such as fertilization and larval development.
Yes, we now have examples to describe such states: frogs and tadpoles.
Their respiratory organs as children are gills, and when they grow up, they will "metamorphose" and breathe in their lungs.
Isn't that particularly troublesome? You also have to be 'perverted' once. Therefore, some salamanders that are not willing to "live by the water for a lifetime" have begun to evolve again.
How can we correct this problem of spawning and larval development in water? It has to be changed from the source. Our ancestors were fish, and even if they grew lungs, their larvae would not be able to breathe directly.
What to do, teach the little tadpole to breathe? Concubines can't learn it! Then find a way to wrap the little tadpole and let it pass this stage and come out again!
Therefore, we probably grew into such an ancestor, and evolved a protective membrane, that is, amniotic membrane. The amniotic membrane is divided into several layers, which can bring oxygen in and drain the waste.
At the same time, the process of "perversion" is too perverted, and it disappears with the appearance of amniotic membranes.
Losing the limits of spawning must be in the water, the vast continent is truly displayed before our eyes.
<h1 class="pgc-h-arrow-right" > several choices, several directions</h1>
The continent is too big, because there is no navigation, this large group of amniotic animals scattered, went to completely different places, also has a completely different living environment, and naturally has a different evolutionary direction.
We specifically shared why this phenomenon occurs in the sub-headlines, if you are interested, you can go to see.
The original amniotic animals also had a head like a fish. Such a head, let's say, is not good at first, and then it is not easy to use.
The early amniotic skull was a whole bone with only two places to interact with the outside world. One is where the eyes are long, and the other is the nostrils used to breathe. Originally, everyone lived in the sea, and with fewer holes, the brain was not easy to enter the water. Now that it's out, the hole isn't enough.
The first is to add an additional ear hole on the lower side to lengthen the ear. Most of them have fixed zygomatic arches , hence the name Zygomatica.
Yourself, your cats, dogs, and dogs, the lamb skewers you'll eat after work, are all toxoplastics.
The second kind of person thinks that it is not good to open one, in case it is not enough one day? So they opened one more hole, two in all, all behind the eyes.
What is this hole for? With this hole, the mouth can grow bigger, the bite force is stronger, and it is more ferocious. The finger-biting toys you played with when you were a kid have exactly the same position and function as the screws, just like the two-hole animals.
We looked for a demo. In particular, this advertisement has a typo: reaction yìng.
The teeth of the two holes are good, and five people are chewed up in one breath without panting. Slowly, they moved to the top of the food chain and became dinosaurs. (There are very few dinosaurs that are anterior inferior holes.) ）
After a long, long time, some of them merged the two holes and became birds;
Some have degraded the holes underneath, and these animals have gone extinct;
Some of the two holes are not returned to the water, which is now the turtle.
They were all the same fish that came ashore, but starting from the hole, they took a completely different path.
The two-hole dinosaurs successfully ruled the earth and seemed to have an endless task; our mammalian ancestors, the lower holes, could only fly and dogs, and live by picking up leftover garbage that dinosaurs did not eat.
Is that our evolution in the wrong direction?
Not. This kind of bite force is exchanged for brain capacity.
Dinosaurs are born at level 3, adult level 9, good attributes, all kinds of invincible in the world; single-hole animals were born only 1 level, the attributes are not bad, can only develop.
After hundreds of millions of years, we have reached the level of 999.
The difference between the two sides is getting bigger and bigger, especially when it comes to having children. Children are fragile, and dinosaurs are afraid that children will not live long after they are born, turning that layer of amniotic membrane into an eggshell.
Laying eggs, this reptile symbol finally appeared. Think of dinosaur eggs, pollution-free and high-protein, it is still very exciting.
What about our ancestors? Although the amniotic membrane did not evolve into a hard shell, they also had to lay eggs and incubate eggs.
However, these good places in the tropics have been occupied by dinosaurs, and our ancestors did not dare to go, so they could only run to fight the wild. But the wild area was too cold, and they began to produce meat and began to grow hair.
But here's the problem: I've produced my own flesh, but the eggs that have just been born can't stand it!
In order to ensure the survival of the eggs, the single-for-poropods opened the ultimate cub protection mode: the first step is to ensure that their body temperature is warm and can hatch eggs.
The second step is to get the cubs out earlier and use milk to supplement the cubs.
Yes, the mammalian lactation has finally appeared, and this day is 225 million years ago, which is the hidden king beast above.
They lay eggs and hatch, but they also breastfeed, and the platypus that still exists today is one of these creatures of the order Monotreme mammals.
This is still not allowed! The survival rate of the eggs is too low, and the hatching is too wasteful of time! And how to get single moms out to work! Discrimination against women can not be better! Cold and shaky!
Therefore, in order to make it easier to work, some [protozoae suborder] organisms evolved bags and chose to put eggs into the bags to hatch.
Don't get excited, it's not what you think, it's about this commodity - the needle.
Mentioning this, I have to say that these two above are the only remaining [protozoa suborder] animals, and they only exist in Australia. It was because of living on an isolated island that it survived to this day.
These two animals are not numerous, and they may be close relatives of our true ancestors.
If you pick up one... Cherish life, reject wild food, start with me.
<h1 class= "pgc-h-arrow-right" > is an endless epic</h1>
The echidna in front of it grew a bag, and it seemed that it no longer had to worry about the hatching of the hemp. But here comes the problem. Packed in a bag, once the echidna mother moves around a lot, or accidentally falls on the head, the consequences are a little too serious.
Imagine this: you wear a coat with a pocket on your belly, then put four or five eggs in your pocket and go out for a day shift. I felt that this trip down, the clothes could not be washed out.
So what! It's not safe to put it in the bag, so do I put it in my stomach?
That's right, and just like that, an epoch-making evolution happened: the placenta.
With the placenta, mammals are completely distinguished from the original reptiles.
Viviparation sacrifices a certain reproductive efficiency, but improves the protection of the fetus and increases productivity. At the very least, getting pregnant in October is easier than hatching eggs in October.
Coupled with the process of breastfeeding, mammals have the most basic emotion: maternal love.
But even with the placenta, many animals keep their nursery bags.
Kangaroos, thylacines, koalas... Basically, it is still only preserved in Australia.
Notice that they are not the same as echidnas, they are not oviparous, they are born and put back into the bag.
These marsupials are called the "posterior theopods of the order Monotreme".
But one mother was not happy: the bag is too ugly! And I'm so hungry! I can't go out with my baby to forage!" Can't you have a life of your own? When will we actually stand up! Cold and shaky!
Thus, the creature without a bag appeared below.
Climb the Archaeopteryx.
It may have been the first creature of the order Monocephalus.
What's more, it's the last common ancestor of you and cats, dogs, and dogs, and almost every mammal you know.
It didn't know itself, and was about to begin its journey to conquer the planet.
And these are the stories of the next issue.