Are all the animals in the Ice Age real? Or prototype?

Mammoth. Mammoths, the primitive animals, were distributed all over the world in the Stone Age, and now they are extinct. However, paleontologists can still find well-preserved mammoth bodies in Siberia and other places. Mammoths are similar in shape to modern elephants, but according to ancient records, their weight is equivalent to that of modern blue whales. Its skull is very sharp. The most unusual thing about mammoths, which is different from modern elephants, is that they are covered with hair, and the length of hair can even fall to the ground; The elephant's neck protrudes into a peak and its ears are smaller. A layer of tawny unkempt long hair mixed with black long hair covered the mammoth's whole body, even on its ears. The shape of ivory is also very strange, spiraling inward, and the tips of two teeth are opposite. Mammoth is the only elephant that can survive in the Arctic climate, and all this depends on its long hair. Mammoths have lived in Siberia for a long time. During the ice age, mammoths were found in Britain, France and North America, but after the warming of the climate in Britain and France, mammoths also migrated northward with the retreating ice. Mammoths in these areas can be up to 4 meters tall and extremely heavy, so they will fall into the cold and muddy ground. When the soil freezes, elephants will be frozen inside. The earth had several ice ages about 654.38+0.5 billion years ago. The so-called ice age is the sharp drop of temperature on the earth, and the vast area of high latitude on the surface is covered with ice all the year round. If animals that survived the ice age are to be represented, mammoths can be taken as an example. Mammoth is an animal that appeared in the middle alluvial period about 370,000 years ago, but it became extinct before 1000 years ago. He has long brown hair and big curved teeth. Its long hair and thick subcutaneous fat can protect the body from the cold, and its long teeth can help it dig up the snow-covered grassland. Mammoths are found in Europe, Siberia, North America and Hokkaido. Bones, skin, meat and hair were excavated from the permafrost in Siberia, and the fossils completely preserved the shape before freezing. As many as 25,000 such frozen mammoths were found intact. Mammoths' bones have been known in Europe since at least15th century, but they have been regarded as the bones of giants for hundreds of years. At these early stages, our knowledge about these extinct elephants began to form. We have many well-preserved bones. Frozen corpses can often be found in permafrost in northern Siberia and Alaska. They have been preserved in the "refrigerator of nature" for tens of thousands of years. 2. Saber-toothed tiger appeared in Oligocene 35 million years ago, and later it lived to 6.5438+0 million years ago in Pleistocene. This is a branch of evolution of big cats. It lived in the Pleistocene-Holocene from 3 million years ago to10.5 million years ago, and spent nearly 3 million years with its evolving human ancestor * *. The shape of saber-toothed tiger is similar to that of modern tiger, but its upper jaw canine teeth are much larger than that of modern tiger, even larger than those of wild boar and male beast, just like two short swords with inverted handles. The canine teeth of carnivores are a killing weapon for preying on prey. The normal situation should be that the upper and lower canine teeth develop evenly and can bite the prey when attacked. However, the upper canine teeth of saber-toothed tiger have evolved so much that the lower canine teeth have degenerated disproportionately, which may be specially used to deal with large thick-skinned herbivores such as elephants. Such a special and grown canine tooth can penetrate deep into the prey with only one pair, and enlarge the wound as much as possible, resulting in massive bleeding and death of the prey. Accordingly, the skull and some muscles of the saber-toothed tiger's head have also changed accordingly, the mouth can be opened wider, and the mandible and skull can form an angle of more than 90 degrees, thus giving full play to the role of saber-toothed tiger. But this extremely specialized development obviously has its disadvantages, that is, it greatly reduces the adaptability to the environment and prey. With the extinction of various large thick-skinned herbivores in the Pleistocene, the saber-toothed tiger, which was not good at running fast, gradually became useless, unable to compete with those flexible and all-round carnivores, and died out with its prey. On the contrary, modern tigers and other large carnivores appeared later. The saber-toothed tiger is very big. The largest species (Thylacosmilus atrox) has a shoulder height of about 1.5m, and its weight is equivalent to that of four adult men and twice that of a lion. Although it is not tall enough, its body is very strong, especially its forelimbs. Its most striking place is undoubtedly the head-two saber teeth 18 cm long are deeply buried in the upper jaw, almost at the same level as the top of the head; The mandible has a huge protective lobe protruding downward. Although this kind of blade is beneficial to protect the protruding saber teeth, it also increases the risk of fracture and infection, and also causes the head to become heavier, which affects the flexibility of action to some extent. 3 sloths The slothfamily includes Bradypus, a three-toed sloth, and Choloepus, a two-toed sloth. Each genus has one or several species, and there are ***5 species due to different classification systems. Mainly distributed in the tropical rain forests of Central and South America. The three-toed sloth has three toes in its forelimb and hind limb, while the two-toed sloth has three toes in its hind limb and two toes in its forelimb. The number of cervical vertebrae between them is also different. Among them, the three-toed sloth has 9 cervical vertebrae, which is the most species among mammals, while the two-toed sloth has 7 like most mammals. Because of the great difference in structure between three-toed sloth and two-toed sloth, some people put them into different families. Three-toed sloths only exist in the slothfamily, while two-toed sloths are closely related to extinct sloths, which can be classified into the slothfamily of the slothfamily. Three-toed sloths can form a slothful superfamily, and slothfamily and slothfamily form another slothful superfamily. The sloth has been highly specialized as an arboreal animal and has lost the ability to move on the ground. Usually hanging upside down from the branches, the hair is fluffy, quasi-directional, and it is hard to find in the forest. The three-toed sloth is widely distributed, reaching Honduras in the north and Argentina in the south, and the two-toed sloth is slightly narrower, reaching Nicaragua in the north and Brazil in the south. The adaptive range of sloths is very different from that of anteaters belonging to Tatatales in Ya Dun. They are strictly arboreal and simple herbivores. The skull is short and high, the nose kiss is obviously shortened, and the zygomatic arch is strong but incomplete. The number of cervical vertebrae in the family deviates from the seven-vertebra model of ordinary mammals, with 6-7 two-toed sloths and 9 three-toed sloths. This change occurs not only between species, but also between individuals of the same species. No more than 3 visible toes, toes and feet. The three-toed sloth has the same length, the base of the tumbled bone and the attached bone are healed, its claws are strong and hooked, its size is small, its weight is 4-7 kg, and its hair is long and thick, which provides living conditions for algae. In the rainy season, algae grow in the depressions on the surface of hair, making light-colored fur green.