The turtle is a pet that young people like to keep nowadays, and it is a representative of honesty and honesty in our eyes. But for scientists, the turtle is their "nightmare", even moreThe ultimate bug in evolutionWhy is that?
Slow-moving turtles.
In 1859, Darwin published "The Origin of Species", in which he expounded the theory of evolution, in which he believed that "creationism" had no basis, and in this book, he mainly stated two views.
The first point is that all species are not static, and that organisms will produce a variety of things as their environment changesEvolution。After the publication of this book, more and more biologists believed that the "theory of evolution" was correct.
The evolution of horses. The second point that Darwin makes in his book is:Natural selection, survival of the fittest。Animals have limited habitat and food, and many animals have evolved to change their habits in order to avoid food conflicts.
For example, the giant panda we are familiar with actually liked to eat meat before, but as more and more carnivores migrate to their habitats, they can only switch to bamboo to ensure their survival rate.
Biological evolution is the result of natural selection, and only those that can adapt to their environment will survive, and those that cannot evolve with the environment will eventually be eliminated.
The evolutionary process of giraffes.
Some organisms undergo "favorable mutations" in the process of fighting each other, resulting in the creation of new species. These favorable variations are usually preserved as the species reproduces, thereforeOrganisms are forever in evolution
For most creatures, Darwin's theory of evolution is suitable, but the turtle is like a bug in evolutionScientists still don't have a definitive answer about the formation of turtle shells
The tortoise's shell is one of the more peculiar creatures in life, and it evolved from the ribs and spine. In nature, with the exception of tortoises, no species has its bones directly exposed.
The human analogy with the skeleton of a tortoise.
This is actually acceptable to us, because after all, each creature has its own uniqueness, just as humans are the only animals with autonomous consciousness.
Comparing the fossils of Australopithecus, we can know that the earliest humans lived in trees, and after a period of evolution, humans gradually approached the land and slowly learned to walk upright.
Human evolution. The field of vision on the ground is much wider than that of trees, so the vision system of Australopithecus had to evolve accordingly to adapt to the environment on the ground, and in the process of evolution, the brain gradually developed.
It is only through fossils that we can draw definitive conclusions, no matter whatIncreased brain volume, or the thicker and thicker knee joints, can prove that human beings are constantly evolving.
Changes in brain volume.
On the other hand, we have not found many fossils in the evolution of turtles, and turtles are relatively ancient species, which means that it is very difficult to find the fossils of turtle ancestors.
According to the conventional analysis, the turtle shell is more important for each turtle, the process of evolving the turtle shell should be relatively slow, and there should be more fossils in the evolution of the turtle shell in nature.
But all the fossils of turtles found over a long period of time have intact shells, including the original snapping turtles from the Triassic period.
It wasn't until 2008 when a fossil of a "half-carapace-toothed turtle" appeared that scientists determined that the shell was formed inside the turtle's body. The half-carapaceed turtle has no shell on its back, only a carapace on its abdomen. The discovery of the semi-carapace-toothed turtle is ample evidenceThe shell is formed in the ribs of the tortoise
"Semi-carapace-toothed turtle" fossil.
The only difference between turtles in ancient times and tortoises today is their heads and limbsCannot be retracted into the turtle shell, which raises new questions? Isn't the point of turtle shell evolution to protect turtles from predators?
The discovery of the semi-carapace-toothed turtle brought scientists to the attention of an even older speciesTurtle due south。The South turtle lived during the Permian period and became one of the few species that survived a mass extinction.
The ribs in the body of the southerner turtle account for a considerable proportion of the ribs, and these ribs are relatively hard. Some biologists believe that it was the southern turtle that evolved long, wide ribs to escape natural disasters and migrated underground.
The tortoise's ribs are getting wider and wider.
In other words, the turtle shell was originally formed for the purpose of digging into the ground, which was just a way for the southern turtle to survive in the harsh environment, and using the turtle shell to protect itself was only the subsequent evolution of the turtle.
Knowing about the formation of turtle shells, scientists began to study the origin of turtles, but in the course of this research, scientists found that the problem was more complex than the formation of turtle shells, and could even be called a "nightmare".
Initially, most scientists believed that the ancestor of the turtle was a protosnapping turtle, which lived about 196 million years ago, and its body structure was similar to that of today's turtles, most importantlyThe shell is also directly attached to the skeleton in the body
Snapping turtles. With the excavation of the fossil of the semi-carapace-toothed turtle in 2008, scientists believe that the ancestor of the turtle is the half-carapace-toothed turtle, and the turtle species should have been around for nearly 2300 million years.
In 2015, German scientists discovered a fossil of an ancestral tortoise, a discovery that renewed people's perception of the origin of the tortoise, which lived about 2 years agoThe era of 400 million years ago.
As people continue to deepen their research, scientists have discovered the existence of the Zhengnan turtle, which mentioned above that in order to survive the mass extinction era, the Zhengnan turtle evolved relatively large ribs to dig holes, so as to create a place for itself.
Reconstruction of the southern turtle.
Most biologists today believe that the South Turtle is the ancestor of the current turtle. But primitive tortoises areThere are teethThe current tortoises are toothless, and the evolution of this may still need more biologists to study.
Or maybe one day in the future, humans will discover even more ancient turtle fossils and overturn the existing view. As long as scientists follow the clues of the evolution of the turtle shell, one day they will find the true origin of the turtle.
In addition to the fact that the evolution of the turtle shell is contrary to evolutionary theory, the turtle is also a bug in evolution in some other ways.
Turtles. The first is the well-known "tortoise and hare race", the tortoise travels very slowly, and most animals will evolve a relatively fast speed in order to hunt or avoid predators, and the tortoise is an exception.
The tortoise that has survived on the earth for hundreds of millions of years should have evolved into a powerful state, whyTurns into one of the slowest creaturesThis? Haven't they evolved in terms of travel speed?
The slow movement of the turtle is due to the fact that the shell wraps around the legs, so the tortoise's limbs cannot move flexibly, and when they reach land, their small body needs to support the heavyweight shell, which is also a reason for the slow progress of the tortoise.
Teeth are very important in our thinking, but the turtle has lost teeth in long-term evolution, which is also a bug in the theory of evolution.
The second is that Darwin's "On the Origin of Species" states that reproduction is essential for every species. But the sex of the turtle cub is not determined by chromosomes, but:Controlled by temperatureTarget.
If the temperature of the turtle's nest is around 25 degrees Celsius, the hatchling turtle pups will be male. If the temperature of the turtle's nest is around 28 degrees Celsius, the hatched cubs are the female.
Turtle eggs. There are many wonders in the world, and the current exploration of living things by human beings is still insufficient, and only by continuous excavation and continuous research will the origin of living things be thoroughly studied.