According to RIA News Agency reported on June 20, a group of biology graduates discovered two ichthyosaur rib fossils on the coast of a small island in Vladivostok . The fossils have now been shipped. Go to the local aquarium and wait for technical processing. The ichthyosaur fossil was excavated from the seaside gravel. This is the third time that ichthyosaur fossils have been found in this area in the past ten years. Since the ichthyosaur bones discovered this time are relatively fragile, in order to protect the fossils, the aquarium has It has been decided not to display it to the public for the time being.
Some netizens are curious about this, what kind of prehistoric animal is the ichthyosaur? As the overlord of the ocean, why can't it escape the fate of extinction? Today, the editor uses this topic to talk to readers about fish and dragons.
So what kind of prehistoric creature is the ichthyosaur?
In fact, ichthyosaurs are creatures that lived in the same period as dinosaurs, and even ichthyosaurs appeared earlier than dinosaurs. Paleontologists discovered that this was an ancient Mesozoic marine creature that lived 250 million years ago. It went extinct only 90 million years ago.
The body length of ichthyosaurs usually ranges from 1 meter to 25 meters, which is a very large span. This also means that the size differences between different types of ichthyosaurs are very large. Paleontologists reconstructed the appearance based on the fossils. Its appearance was somewhat similar to the current dolphin , with flippers to maintain balance in the water and a strong tail fin, but the ichthyosaur is neither a dinosaur nor a fish. family, it belongs to the terrestrial reptiles. Over the long years of evolution, it returned to ocean life and eventually evolved into ichthyosaurs, which are marine reptiles whose evolutionary process is similar to that of today's whales.
Paleontologists also discovered an interesting phenomenon. The breathing method of ichthyosaurs was very similar to that of today's whales. They both used their lungs to breathe, so they would float to the surface of the water every once in a while to breathe.
The heyday of the ichthyosaur family was during the Cretaceous. At that time, they could be found in almost all oceans around the world, and they also had their own dominant position in the ocean. However, in fact, paleontologists still have not figured out their specific evolutionary trajectory. , there is still little known about them, and this fossil discovery will also help researchers further reveal the secrets of this group of ichthyosaurs. Why can't
, as the overlord of the ocean, escape the fate of extinction?
The modern scientific community is not yet completely certain of the specific reasons for the extinction of ichthyosaurs, but there are two more traditional theories: climate change and the slowdown in the evolution of ichthyosaurs in the later stages. The so-called prosperity must decline, and any species follows this rule. This natural development process, ichthyosaurs are no exception.
Paleontologists have discovered that in the late Cretaceous period, the earth experienced an oxygen-deficient oceanic event from the Cenomanian to Turonian periods, which led to a large-scale global biological extinction event. During that period, the earth's climate was very unstable. It was difficult for organisms that had adapted to the warm environment at that time to adapt to the sudden changes. It was especially fatal to large and medium-sized animals, including ichthyosaurs. Various signs also indicate that during that period, ichthyosaurs slowed down their pace of evolution. Once the evolution speed failed to keep up with the changes in the global environment, the only outcome would be survival of the fittest.
Moreover, during the Cretaceous period, the competition for the survival of the fittest was also very fierce. During that period, both on land and in the ocean, there were many species, and natural enemies of ichthyosaurs also appeared in large numbers, causing the population to continue to decrease. Once the evolution speed of a species slows down, it will all be the same. It is a very terrible phenomenon. Therefore, in order to adapt to the constant changes in the earth's environment, living things can only achieve the continued development of the race by evolving all the time.
Some netizens asked, the current dolphins and ichthyosaurs look exactly the same in appearance. Could the dolphins be the descendants of the ichthyosaurs?
Ichthyosaurs look almost exactly the same as the dolphins we are familiar with today. Some of their living habits are also the same. For example, ichthyosaurs also need to go to the sea from time to time to breathe. They are also viviparous , which is simply a dolphin. A copy of , are dolphins really close descendants of ichthyosaurs?
The answer is no. In fact, ichthyosaurs are a kind of reptiles that live in the ocean. Paleontologists believe that their ancestors are the same as mosasaurs. Both were made of different lizards that were limited by They were forced to retreat to the ocean to live in the terrestrial environment, and finally evolved into the overlord of the ocean.
Even paleontologists have found the ancestors of dolphins, which should be a mammal that lived on land - Pakitherium , which is a land mammal that looks more like a dog and not like a lizard at all. During the evolutionary process, they slowly retreated from land to live in the sea, and finally evolved into dolphins. Therefore, ichthyosaurs and dolphins are essentially two different animals. Ichthyosaurs have completely disappeared from the earth during the Cretaceous. In this regard, do you think there are still living descendants of ichthyosaurs today? You are also welcome to leave messages and interact with us in the comment area!
