So, what caused the extinction of dinosaurs? The gradual change theory seems to make sense. According to the gradual change theory, the extinction of dinosaurs was caused by the change of environment. At the end of Mesozoic, the orogeny led to great changes in the climate and environment, and reptiles were eliminated because of inadaptability. The rise of mammals made reptiles at a disadvantage in the competition for survival and was eventually replaced by mammals. The above is the gradual theory of dinosaur extinction.
The change of climate and environment caused by orogeny is very slow, and the possible evolution speed of almost all organisms can't keep up with the change of climate and environment caused by orogeny. Therefore, the climate and environmental changes caused by orogeny can hardly lead to extinction, but only lead to accelerated evolution and become a new genetic species.
Moreover, it is difficult for orogeny to change the climate environment in all places. There should be some places where the climate and environment have not changed. This unchanged place should still be a paradise for dinosaurs.
In the age of dinosaurs, the climate and environment should have changed many times in more than 100 million years. Why did the other times not lead to the extinction of dinosaurs, but the one in 65 million years may lead to the extinction of dinosaurs? Is it just one more mammal factor? Maybe so!
The real extinction factor of dinosaurs is the evolution of mammals. Mammals are the only factor in the extinction of dinosaurs. It was mammals that wiped out dinosaurs. Dinosaurs are losers in the competition for survival. However, by this time, dinosaurs have ruled the earth for more than 100 million years. It is the strongest in more than 100 million years.
From the point of view of individual competition, the survival ability of adult dinosaurs is no less than that of adult mammals. About 65 million years ago, adult dinosaurs were more viable than adult mammals. However, dinosaurs were eliminated by mammals. The most important factor is the difference in breeding methods, which determines the fate of competitors.
Dinosaurs are oviparous and mammals are viviparous. Mammalian reproduction may be much more complicated, so evolution is relatively difficult. Or maybe not, evolutionary difficulties caused by reproductive complexity. In a word, the evolution of mammals is much more difficult than that of oviparous reptiles. Therefore, the reproductive evolution and other evolution of mammals are progressing all the time, and their advantages are gradually accumulating. In the competition with dinosaurs for more than 100 million years, the overall viability is not dominant. However, at least not completely eliminated. In this 100 million years, dinosaurs are evolving, and mammals are also evolving. In this hundred million years, the evolution speed of mammals, compared with dinosaurs, has never been dominant. Dinosaurs have always been the best in their generation, while mammals have always followed in obscurity. In this way, 65 million years ago, the evolution of dinosaurs was finally exhausted, while mammals were still evolving rapidly. At this time, the evolutionary journey of mammals has made great progress. I don't know what great progress has been made. This big step has finally opened the distance of competition with dinosaurs, and the overall viability has gained the upper hand. Dinosaurs are about to be pushed out of the historical stage.
Viviparous and oviparous, finally showed the advantages and disadvantages.
At some point in the life of dinosaurs, the disadvantage of spawning is very obvious. After the dinosaurs laid eggs, it took a period of time, days, or ten days, dozens of days to hatch young dinosaurs. This is a fatal flaw. This is probably the only reason why dinosaurs were eliminated by mammals.
Mammals give birth to offspring, which are viviparous. This is a greater advantage than spawning. Because, parents can better protect their offspring, just because they can move with the fetus relatively freely, avoid danger or get food. Eggs do not have this advantage. During the incubation period, it is really inconvenient and dangerous for some non-carnivorous dinosaurs.
When the evolution level of mammals is relatively poor and the individual competitiveness is still very weak, mammals mainly rely on their own special breeding methods and viviparous to make up for their other shortcomings. In this way, you can get your own place, but you are completely at a disadvantage.
At this time, dinosaurs are dinosaurs that threaten dinosaurs, and mammals are basically affiliated. Dinosaurs are all eggs, so there will be no winners in this respect. Although there are still egg thieves, these egg thieves are basically dinosaurs and will inevitably evolve ways to guard against each other. Will reach a balance with each other. As a result of balance, the population size of everyone has decreased a little.
However, when mammals get a key evolution, their survival ability has made great progress. At this time, if they become or remain egg thieves, dinosaurs will be easily defeated in the evolution of competition with dinosaurs for stealing and keeping eggs. There will be an evolutionary imbalance and the disappearance of one side is inevitable.
Herbivorous dinosaurs were the first to be extinct. This is the first dinosaur group that failed in the egg stealing operation. It is conceivable that it is the most difficult for herbivorous dinosaurs to hatch their offspring. Grass is not rich in nutrition, and herbivorous dinosaurs need a lot of food. You need to eat grass and leaves for a long time every day. It is difficult to keep your eggs all the time when you need to leave the spawning place. The companions of herbivorous dinosaurs could not transport food, so they probably evolved to take turns to guard the eggs laid by their companions and avoid being stolen. This step of evolution is difficult and inconvenient. Even if it can successfully evolve to this stage, it will greatly weaken the viability of this herbivorous dinosaur population. In fact, it is to reduce the total number of individuals per unit area of this herbivorous dinosaur population. Then the population number of carnivorous dinosaurs and the number of individuals per unit area will inevitably decline. The possible decline is not proportional to the carnivorous dinosaurs. The reason is that mammals can be used as food.
Herbivorous dinosaurs should be easily found by carnivorous dinosaurs when guarding their eggs, which will also greatly reduce the viability of herbivorous dinosaurs.
Moreover, when the carnivorous dinosaurs scared away the herbivorous dinosaurs that guarded their eggs, in this gap time, perhaps mammals would take advantage of loopholes and steal the eggs laid by herbivorous dinosaurs. This may have serious consequences and may be the most important way to reduce the number of herbivorous dinosaurs. It seems that the possibility of extinction of herbivorous dinosaurs is very high. It is too difficult to protect eggs, which is the biggest advantage of mammals over dinosaurs, and there is no need to protect eggs.
These mammals may be small. Small individuals, it is very beneficial to hide and avoid carnivorous dinosaurs.
Big grass and small grass eat dinosaurs, and it seems that extinction is inevitable. It's too difficult to protect the egg, so it died.
Carnivorous dinosaurs were nutritious and small in size because their food was meat. You can evolve two patterns to protect your eggs. One is to catch prey with one of your collaborators and then eat with them. One is to take turns catching prey and eating their own food. It is more likely to evolve the former. Carnivorous dinosaurs can evolve to the level of protecting their eggs without even giving mammals a chance to steal. But what will happen at night? Can carnivorous dinosaurs guarantee to rotate guards with their partners? Can you promise not to sleep? The number of carnivorous dinosaurs should not be too concentrated, generally there are two large carnivorous dinosaurs. There will be more small carnivorous dinosaurs. It seems difficult to guard at night, and it is easy to be used by small and exquisite mammals.
More importantly, however, the large decline in the number of herbivorous dinosaurs per unit area has a greater impact on the survival of carnivorous dinosaurs, which will reduce the population size of carnivorous dinosaurs and increase the probability of extinction. It seems that carnivorous dinosaurs may have died like this.
Could it be that a small, exquisite, love-eating, good-eating, dinosaur-egg-eating and omnivorous mammal evolved, which led to the extinction of dinosaurs? Maybe that's it! However, it should be at least 65 million years ago that a certain mammal made great evolutionary progress, which greatly improved its viability. This big step opened the distance from the survival ability of dinosaurs, which led to the extinction of dinosaurs.
In fact, dinosaurs died because of the theft of mammals. It was the theft that killed dinosaurs.
Those reptiles that are not good at protecting their eggs, to be precise, those with high protection costs, have all died out. And those reptiles with low protection cost mainly rely on the hiding and concealment of eggs. There are still some survivors of this reptile. Such as turtles, crocodiles, snakes and so on. Of course, small eggs are easy to hide, and snakes are probably such a hiding method. Turtles hide in the sand.
There is also a big category, which is also oviparous and birds. Birds will not die because they lay eggs, because birds can lay eggs where mammals can't reach them, or where mammals can't reach them. Such as trees, cliffs and so on.
These surviving reptiles, as well as birds, can also indirectly prove that dinosaurs did not perish because of natural disasters. All catastrophe theories must explain the surviving reptiles and the reasons for their survival.
I also estimated a small factor, constant temperature is one of the reasons why mammals beat dinosaurs. Because constant temperature is the basis for the further evolution of the brain, it is possible for the brain to become smarter. Maybe that's why mammals beat dinosaurs.
Perhaps dinosaurs also evolved a constant temperature body. If so, everyone has no comparative advantage at this point.
Is it true that only warm-hatched eggs can appear, and constant-temperature egg-laying animals? If so, dinosaurs with constant temperature need to hatch their offspring with their own bodies, which is even more unfavorable for their survival when hatching eggs.
In a word, it doesn't matter whether dinosaurs are at constant temperature or not, and it basically doesn't affect their own demise. Then mammals don't need the advantage of constant temperature, and the possible advantage of constant temperature in mammals can be basically ruled out. Because, don't need this advantage. You only need the advantage of viviparous to defeat dinosaurs.
Some hypotheses suggest that the extinction of species at the end of Triassic is probably similar to the extinction of dinosaurs I mentioned above. Was eliminated by other creatures. The pattern of biological extinction at the end of Permian, Devonian and Ordovician is probably similar to that of dinosaur extinction. It is also possible that some of them are not similar. In a word, the extinction mode of dinosaurs is an important biological extinction mode, which was eliminated because of the competition of other creatures. This is also a mode of mass extinction.