What 'flaws' did the evolution of the tortoise leave behind? Why does it give scientists a 'headache'?
Turtle is a very common marine creature to modern people, but this creature is quite special to ancient people. If you often read fantasy novels, you must be very familiar with "Xuanwu", another word for tortoise. In ancient times, people called tortoise Xuanwu. Those who believe in Taoism should have a deeper understanding of Xuanwu.
Xuanwu is connected to the north, and the underworld happens to be in the north, so people think that Xuanwu can be used for divination. It is connected with the underworld, which is why ancient people used turtle shells for divination.
What "flaws" did the evolution of the tortoise leave behind? Why does it give scientists a "headache"?
- Turtle
When mentioning the creature of turtle, does a turtle shell immediately pop up in everyone's mind? The biggest feature of turtles is that they have shells. When in danger, the tortoise can retract its head and feet into the shell, so that the enemy can't do anything about it.
Why did this creature evolve a turtle shell? Scientists have also conducted research on this kind of creature, and repeatedly hit the wall during the research. Many scientists think that turtles are like nightmares.
The tortoise is a relatively tenacious creature, and it is not a picky eater. In the ocean, it will eat small fish and shrimps. If it is raised at home, it will eat fruits and vegetables even if it is fed to it. Moreover, the tortoise's anti-hunger ability is very strong, and it can persist without eating for a long time.
Since when did this creature appear on earth? It may have existed for much longer than you think. Scientists speculate that tortoises appeared 200 million years ago. At that time, it was also a critical period for the growth of gymnosperms. So what happened to the tortoise shell?
The tortoise shell is the protective umbrella of the tortoise. Scientists have conducted research to know that the shell on the tortoise's body was originally their ribs. Because the ribs have been growing outwards, and finally combined with the shoulder blades, even the spine on the back is also fused, and this is the turtle shell that people see.
But not all turtles can use their shells to protect themselves. There is a creature called a sea turtle in the ocean. Because the shell on its back is relatively large, its movements are very slow, it is difficult to catch food, and the turtle has no way to retract its body into the shell.
- Discoveries of scientists
When scientists were studying tortoises, they were always looking for the ancestors of this creature. Until 1887, German scientists discovered a fossil that was considered to be the earliest ancestor of tortoises.
Because it has a similar shape to a tortoise, but the tortoise's head in the fossil is relatively large, and there is no way to retract it into the shell. Scientists believe that this tortoise should be the original snapping turtle.
Judging from the fossils, the back of the original snapping turtle also has sharp scutes, which may also be aggressive. After the discovery of this creature, some scientists wondered what kind of creature the original snapping turtle evolved from.
Most scientists believe that the original snapping turtle may have evolved from Megalodon. However, based on the analysis of the fossils discovered later, the megalodon evolved into a proto-snap turtle, which was untenable.
Scientists did not give up the research on the ancestors of tortoises, and they turned their attention to the southern turtle, which was a fossil discovered in the early 20th century.
This creature also has many similarities with modern tortoises, and it looks more domineering, with raised scales on its back, a neck that is not very long, and the abdomen of Zhengnan turtles does not have a shell.
By 2015, German scientists discovered another turtle fossil, which they named Ancestral Turtle. Although the ancestral tortoise does not have a shell on the abdomen, the ribs of this tortoise are wider than those of the southern tortoise, and its abdomen already has protruding bones.
The more scientists study it, the more they discover. It was even suggested later that the tortoise was originally a reptile that lived on land, but later changed and entered the water.