It is a "pioneer" in the sea
In the Triassic biological fossil group in Guanling, Guizhou, China, there is such an inconspicuous animal fossil, if you are not a professional, it is likely to treat it as a turtle fossil... This animal, together with ichthyosaurs and ichthyosaurs, is called the three major marine reptile groups of the Triassic, what exactly is it? Ichthyosaurs are recognized as the "life star" of marine reptiles, appearing from the early Triassic period and gradually disappearing in the middle of the Cretaceous. There is also a group of reptiles that have been in the sea for almost the same time as ichthyosaurs (or slightly later than ichthyosaurs), which is the "turtle-like non-turtle" of the paleontological world.
Since 1830, when paleontologists first excavated fossils of plesiosaurs, fossils of this strange reptile have been found on continents such as Europe, Asia and Africa. This amply illustrates that during the Triassic Period, " Plesiosaurus " was widely distributed in the oceans of the world. However, the fossils of " Plesiosaurus " were found only in triassic rock formations , indicating that they were wiped out at the end of the Triassic. So, what did the dragon look like, and what was the difference between the marine reptiles we know?
Plesiosaur
How does it swim in the sea?
In 2013, a 246 million-year-old fossil of a diplodocus was unearthed in the Netherlands, which paleontologists say is the earliest fossil of apatosaurus ever found. The news has led people to focus on this obscure reptile again. According to fossil evidence, " " Plesiosaurus " had a striking physical feature that differed from all suprasatos in that it had a turtle-like disc-shaped carapace on its back , with a flattened body that resembled turtles.
However, this disc-shaped carapace has nothing to do with turtles. Many experts have emphasized that the tortoises and dragons in the order Ryosaurus look very similar to turtles, but their differences are like the differences between humans and hedgehogs, and some popular science books will make this mistake. Paleontologists speculate that the reason why the dragons grew such strange shapes may be related to their defenses to consolidate their defenses. However, the heavy disc-shaped carapace also affects their maneuverability to swim in the ocean, greatly reducing the speed of predation. In addition, although the webbeds of the plesiosaur were already grown between the toes suitable for drawing water, its limbs were extremely short and not conducive to swimming. Even more bizarrely, The Dragon had an offbeat vertebrae: its vertebrae were so tightly interconnected that they were not easy to bend, the bones were thick and dense, and they were not suitable for floating in the sea, and their skeletal characteristics undoubtedly affected their mobility.
The dragon is not without its advantages, it prefers crustaceans, so from the perspective of eating, its teeth are very fit. The upper jaw of the dragon had two larger teeth, flat and flat, resembling a small millstone, and such "grinding disc" teeth could easily crush the shell of the mollusk under the impetus of the powerful mandibular muscles. However, in general, the physical characteristics of " Plesiosaurus " were significantly less suitable for marine life than other marine reptiles , so the lack of competitiveness may be an important reason for the premature aging of " Plesiosaurus " in other marine reptiles.
Why is it so "short-lived"?
The clumsy bodies of the dragons, in addition to giving them a competitive loss to other marine reptiles, had a constraint on themselves: they were more dependent on land and could only live in shallow seas near the edge of the continent. In the event of a catastrophic event, the blow to the Plesiosaurus was much greater than the blow to the Ichthyosaurus and Plesiosaur. What disaster do you ask me? Yes, this can only be blamed on the bad luck of the dragon, and the already promising living conditions have encountered a sudden change and eventually become extinct.
At the beginning of the Triassic Period, the magmatic activity of the asthenosphere was extremely intense, forming a great pressure in it. The intense geological movements not only created the continents of Lauya and Gondwana, which were separated from pangaea, but also caused the fourth mass extinction in earth's history. From Florida in the United States to the middle of the Atlantic, large amounts of steam broke through the ground and sprayed high into the air, and the temperature of the surface and the sky closer to the ground surged, and a large number of species ended their lives in the heat. Then, the rapid spread of magma, large areas of forest being annihilated by fire, causing serious damage to the foundations of the food chain...
The catastrophe, known as the "Mid-Atlantic Magmatic Extinction Event," wiped out 70 percent of the planet's species, and the mammal-like reptiles that flourished in the early Triassic and the various crocodiles that dominated the Triassic lands disappeared. The "ostracized" dragon in the ocean can no longer be found after this disaster. However, at that time, the emerging dinosaur body was not very large, and its ability to adapt to environmental changes was much stronger than the subsequent mass extinction, and finally established the status of land hegemony in the later Jurassic.