Ichthyosaurus (Ichthyosaurus)
Length: 12 meters; Weight: 3 tons; Era: Jurassic; Region: various oceans; Food: Carnivorous; Species: Ichthyosaurus.
A reptile that lives in the sea. Ichthyosaurs are not land animals. Its body shape is suitable for swimming, with fin-like structure and streamlined head. It feeds on fish, not plants. It is possible that the larvae were hatched inside the body because it could not leave the water to lay eggs. The ichthyosaur was 4.5 to 9 meters long. According to strict definitions, ichthyosaurs, plesiosaurs, and pterodactyls are not dinosaurs. However, because they lived in the Mesozoic Era and belong to the Reptile class like dinosaurs, most people also regard them as dinosaurs and fish. Dragons look very similar to dolphins and swim very fast.
Ichthyosaurus Ichthyosaurus- -
Ichthyosaurus Ichthyosaurus
Ichthyosaurus swam happily in the sea of ??the Mesozoic Era. At that time, dinosaurs were walking on land superior. To be precise, ichthyosaurs appeared slightly earlier than dinosaurs.
This is what a typical ichthyosaur looks like (pictured above). Yes, it looks like a fish, but it's not actually a fish. They are reptiles like snakes and lizards. It is easy to see that the skull and fins of ichthyosaurs are similar to those of dolphins and whales among mammals.
Early ichthyosaurs had lower limbs like lizards
Early ichthyosaurs appeared in China, Japan, Canada and other regions during the Triassic Period (200 to 250 million years ago). They may also be found in Thailand. From its initial appearance to its extinction, the group of ichthyosaurs survived for 140 million years, of which 20 million years underwent rapid evolution, from a lizard-like shape to a fish-like shape. There are 27 known species of ichthyosaurs.
Among the strange features of ichthyosaurs, the most astonishing are their huge eyes. Among the ichthyosaur eyes measured, the largest, with a diameter of 264 mm, belongs to Temnodontosaurus platyadon. As far as we know, these are the largest eyes ever seen on Earth, surpassing blue whales and giant deep-sea squids.
How big is the ichthyosaur? As far as we know, Shonisaurus popularis and the Tibetan Himalayan Ichthyosaurus (both late Triassic) were about 15 meters long and the largest ichthyosaurs recorded, but there are probably undocumented larger ichthyosaurs. The smallest ichthyosaur was Guishanchaohusaurus (Early Triassic) which was about 70 centimeters long. The weight of different ichthyosaurs may range from a few kilograms to tens of tons. Because there are so few ichthyosaurs that have preserved complete outlines, it is difficult to accurately calculate their weight.
Judging from the material remaining in the stomach of the ichthyosaur fossil, ichthyosaurs were carnivores that mainly fed on squid, but also fish and some other marine animals, similar to today's whales.
There are many reasons to believe that some ichthyosaurs, especially Bigeye Ichthyosaurus, were expert divers. The eyes of fish-shaped ichthyosaurs have very low aperture values ??like cat eyes, which means they have very good lighting performance. According to calculations, if you put a cat underwater and turn off all the lights, it can hunt for food at a depth of 500 meters. The light aperture value of the eyes of Ichthyosaurus bigeye is close to that of cats, but its eyes are larger than cat eyes. In other words, it can accept more images and therefore has stronger vision. Therefore, Bigeye Ichthyosaurus may have seen better than cats at the same depth.
Fossils show that ichthyosaurs were viviparous animals, although it is difficult to believe that marine reptiles evolved viviparous reproduction so early. Every year in mid-June, pregnant female Bigeye Ichthyosaurs swim in groups to surface seas with large coral reefs and seaweed patches to give birth as soon as possible. This environment not only provides a rich food source for the small ichthyosaurs, but also serves as a refuge for them. However, this is not a suitable place for adult big-eyed ichthyosaurs to hunt. Accustomed to hunting in the vast and dark deep sea, it is difficult for them to adapt to the bright sunlight and small space in surface waters, so they will leave soon after giving birth to baby ichthyosaurs.
The first thing the little ichthyosaur does after leaving its mother is to quickly float to the surface and take a breath. They are born active and able to swim freely. Like all animal babies, their heads and eyes are proportionally larger than those of adults. When newborn ichthyosaurs grow up, caves and passages in coral reefs become ideal places for them to hide from predators.
Within a few months, the baby ichthyosaurs will grow up and move into the open ocean.
In 1991, paleontologist Elizabeth Nicos and her colleagues discovered a fossil of this marine animal in a river in British Columbia in western Canada. It was found that this giant beast was 23 meters long, with a skull of nearly 6 meters and a fin of 5.3 meters. Scientists speculated that this animal may be the largest carnivore that has ever lived on our planet. They called it For the ichthyosaur.
Ichthyosaurs swam in the prehistoric seas for 150 million years, while at the same time their close relatives, the dinosaur family, dominated the land. During this time, some ichthyosaurs retained the lizard-like characteristics of their ancestors, while others underwent significant changes, with their bodies evolving into streamlined shapes like dolphins and their living habits similar to those of these mammals. The animals are almost there.
Through the study of ichthyosaur fins, scientists know how this animal moved from land to sea. Their original legs became shorter and flatter, and the toes were connected together and became soft. Smooth fins; their skin is quite smooth and they have a crescent-shaped tail. When these changes are completed, they can swim freely in the water, but on land, their fins cannot support their heavy bodies at all.
Scientists believe that the life of at least some ichthyosaurs is different from that of today's reptiles. For example, today's marine iguanas are still inseparable from the land. They must climb ashore to bask in the sun to maintain body temperature and maintain body temperature. Normal biochemical activities in the body. But many ichthyosaurs no longer need this. Their bodies can generate part of the heat, and their huge bodies are also conducive to maintaining body temperature. Therefore, these ichthyosaurs have said goodbye to land forever and cannot live without water like fish. Roscoe Mortani, a paleontologist at the Royal Ontario Museum in Canada, believes that some ichthyosaurs have a very aerodynamic streamlined body shape, and their crescent-shaped tails are very powerful and can swing flexibly from side to side. In the spring 2002 issue of the journal Paleontology, Motani published the results of his research on an ichthyosaur named Stenopterygius. He said that this ichthyosaur could swim at a speed of 1 meter per second, which is the same speed as today's oceans. The bluefin tuna and yellowfin tuna on the beach are comparable.
But other ichthyosaurs, especially the early species, still partially retain the lizard shape, with long tails and soft ridges, and their swimming speed is not as fast as the former one. Biologist Richard Colvin even believes that the wave-like swimming of this ichthyosaur also affected its breathing, because it would be difficult to swim at high speeds and breathe at the same time that way. Therefore, scientists speculate that these ichthyosaurs may adopt a jumping method. They would jump out of the water from time to time when swimming, just like today's dolphins. In this way, the ichthyosaurs absorbed enough oxygen in the pursuit of prey and were able to swim. Very long distance.
The food of ichthyosaurs is the question that scientists are most interested in. During the study, a large number of belemnites were found in the belly of the ichthyosaur. They are a kind of paleontological fossil formed from the inner shell of an extinct cephalopod that is related to squid. In another ichthyosaur fossil, people found the remains of some undigested fish and turtles. Those turtles were 6 cm in size. They were swallowed whole into the ichthyosaur's belly, and some were crushed by the ichthyosaur's teeth. . In the mouth of an immature ichthyosaur, people found 200 teeth. They are conical, each tooth is 4 cm long, and 1 cm to 2 cm protrudes outside the gums. The ichthyosaur uses these teeth to crush food and then swallow them.
What surprised scientists most were the eyes of the ichthyosaur. Generally speaking, if ichthyosaurs swim fast, they can dive deep, because only by swimming fast can they swim deeper within the limited time they can hold their breath. This is an important ability for them to obtain rich food. Some biologists believe that ichthyosaurs can dive very deep. One important evidence for this is that they have a pair of huge eyes.
It was discovered that an ichthyosaur that was only 9 meters long had a pair of large eyes with a diameter of more than 26 centimeters. They looked like a pair of large plates holding food. This is the largest eye ever found in the world. Another kind of ichthyosaur is very small, only 4 meters, but their eyes are more than 22 centimeters. Compared with their bodies, this is also a pair of surprisingly large eyes. Scientists have not yet found such extraordinary proportions of eyes and body. animals.
However, in today's ocean, there are also some guys with surprisingly big eyes, such as a giant squid whose eyes can reach 25 centimeters in diameter, and the blue whale's eyes can also reach 15 centimeters.
What is the function of big eyes? Two Scottish scholars, Stilt Hanfels and Gram D. Blackston of the University of Glasgow, published an article saying that in the dark ocean, large eyes can collect more light, which is helpful for discovering hidden objects in the ocean. Small animals in deep water, and sensitive vision also allows ichthyosaurs to cooperate in chasing prey in dark deep waters.
Some people have questioned this view. Modern mammals, such as seals, do not have such large eyes, but they can also hunt flexibly in deep water. But Braxton countered that although seals do not have big eyes, they have other sensitive sensors, such as tentacles, which can detect changes in water flow caused by the activities of animals, and some whales rely on sonar to chase food.
So do ichthyosaurs have a similar detection system? Australian paleontologist Benjamin P. Kyle and another radiographer, George Cowlis, hope to uncover this secret through CD scanning technology. The object they scanned is the fossil of a juvenile ichthyosaur.
Kyle and the others found that there was indeed an inner nose-like structure between the top of the skull and the upper palate of the ichthyosaur, which was very much like an organ responsible for the sense of smell. There are also some strange imprints inside the skull, in the brains of modern animals, where there are areas dedicated to controlling vision and smell. They also found deep grooves in the skull. They believe that those grooves are channels for nerves and blood vessels, that those neural networks can transmit information from the front of the ichthyosaur, and that those grooves may even hide some complex sensory systems, such as electric field receptors. Modern marine animals, such as some fish and sharks, have such an organ. Their sensing neurons can detect the electric fields coming from their prey. Scientists say that it is possible that some species of ichthyosaurs also have a similar detection system, because although they have large eyes, there is a large blind area directly in front of them, and the ichthyosaurs may have to rely on some kind of sense. detectors to detect places their eyes cannot see.
Scientists have discovered that the number of ichthyosaur species is closely related to climate changes on the earth. Judging from the fossil discoveries, when the climate was warm and suitable, they were quite prosperous and there were many types. However, during the geological era when the climate was cold and harsh, their types decreased. Research shows that although ichthyosaurs and dinosaurs appeared on the earth at almost the same time, their extinction times were different. Ichthyosaurs gradually disappeared 90 million years ago, while dinosaurs became extinct 25 million years after ichthyosaurs. Years later, it suddenly disappeared from the earth.