Rehe Biota: Discover the most complete fossils of ancient mammals one by one and beasts

In 1997, the Institute of Vertebrate Paleontology and Paleoanthropology of the Chinese Academy of Sciences organized large-scale field excavations in the Western Liaoning region for the first time, and since then, regular excavations have been carried out every year, and a large number of precious vertebrate fossils such as ancient birds and feathered dinosaurs and ancient mammals have been found.

One afternoon in the spring of 1994, Jin Fan, an ancient fish expert at the Institute of Vertebrate Paleontology and Paleoanthropology of the Chinese Academy of Sciences, suddenly received a letter from a retired cadre in Jianping County, Liaoning Province, saying that bird fossils had been found in Beipiao. This was the news that could most touch the most sensitive nerves of paleontologists, and Jin Fan immediately told the news to Li Chuankui, then director of the Institute of Paleovertebrate and Paleoanthropology of the Chinese Academy of Sciences. Li Chuankui, an expert on ancient mammals, immediately informed Hou Lianhai, an expert in ancient birds, and the two drove a long distance to Jianping County, Liaoning Province, and found the letter recipient who was hospitalized in the hospital. The letterer told them that the bird fossils from the north ticket were in Zhanghe, Jinzhou.

Li Chuankui and Hou Lianhai drove to Jinzhou tirelessly and found Zhang He, a fossil collector who played trumpets in the Jinzhou Song and Dance Troupe. Zhang He took out a fossil collected in Shangyuan Town, Beipiao City, saying that it was a LargeStepine bird. Li Chuankui and Hou Lianhai were secretly shocked when they saw that this fossil of the skeleton of the "little rat" was Archaeopteryx, which was obviously a mammal fossil.

But this fossil is undoubtedly an extremely rare major discovery. The two said to Zhang He that this was not a bird fossil, Zhang He did not believe, Hou Lianhai took out a book on the study of ancient birds and said to Zhang He: "You see this is archaeopteryx, what it looks like, what is your fossil." It's not a bird at all. After consultation, Zhang He gave the fossil to Hou Lianhai and Li Chuankui.

Zhang He said his fossil was found in 1993 in a sharp ravine in the village of Fried Midianzi in Shangyuan Town, Beipiao City. Li Chuankui and Hou Lianhai immediately drove to the Jianshan Ravine in Beipiao. In the home of a farmer at the mouth of the JianshanGougou, Li Chuankui and Hou Lianhai found that there were many fossils on the kang, including 5 turtle fossils, but the bones were scraped out of shape, and Hou Lianhai was very distressed to see it. Hou Lianhai later introduced cCTV reporters and said bitterly that local farmers found many fossils and destroyed many fossils, and they only valued the economic interests of fossils, but did not know how to protect fossils, so Li Chuankui and Hou Lianhai inspected the strata of The JianshanGou and returned to Beijing with fossils.

Zhang and beast fossils

This fossil belongs to Zhang He's private collection, and after consultation, Zhang He donated it to the Institute of Paleontology and Paleoanthropology of the Chinese Academy of Sciences, which is undoubtedly a good deed worth encouraging, and Zhang He has also received great honors.

This fossil was unearthed in the same fossil-bearing formation as the One where the Confucius bird was found, so the animal, like the Confucius Bird, lived in the Early Cretaceous 125 million years ago. After research, experts believe that this animal is a new genus of mammals, and named it "Five-pointed Zhanghe Beast". The genus name "Zhang He Beast" is an encouragement to the fossil donor Zhang He. The species name "five-pointed" refers to the fact that the teeth of this animal have 5 tips. After research, it was confirmed that it belonged to the mammals, the suborder Theropods, the order odonta, the Zhanghe and the mammals, which undoubtedly created a precedent for the naming of fossil donors, and he played a huge role in encouraging fossil donation to the country, and many fossils of the Later Rehe biota were named after the names or surnames of fossil donors.

In November 1997, Hu Yaoming, Wang Yuanqing, Luo Zhexi of the Institute of Vertebrate Paleontology and Paleoanthropology of the Chinese Academy of Sciences and their mentor Li Chuankui reported their findings on this animal in the world-famous British journal Nature. They believe that pentachyths belonged to an important branch of early mammals, an extinct paracodont. The fossils of this type of animal that have been found before are only scattered teeth and jaws, so people's understanding of this type of animal is very incomplete, and the five-pointed and animal fossil specimens, except for the tail, have preserved a basically complete skeleton. It is 14 cm long from the snout to the hips, and if you add the tail, it is estimated to be up to 30 cm long. The restored pentagram and the beast really resembled a large rat, with a pointed mouth, round eyes, and erect ears, but its limbs were not erect like those of modern rodents and other mammals. Its limbs and elbows are bent outwards. The limbs of reptiles such as crocodiles are spread outwards and are called lying down. The limbs of the pentagram are between the upright and lying down types, and can also be said to be between reptiles and modern mammals, which is one of the characteristics of primitive mammals. The tooth structure of the pentagram and the beast shows that it is an animal that feeds on insects, but it is not excluded that it also eats some roots, leaves or fruits.

In addition, Zhang and mammals also provide very important evidence for the evolution of auditory function in mammals. Based on the characteristics of Zhang He's head and jaw, we can be sure that there are three small ossicles in her middle ear, so that her hearing is strengthened to a certain extent. However, the finger-shaped promontorium that houses the inner ear of Zhang he and the beast shows that its cochlear tube is straight or only slightly curved, indicating that Zhang He's sensitivity to high-frequency responses is still relatively low. It can be concluded from this that the hearing of Zhang he and the mammals is still at a relatively primary level in lactation, and the perfection of the mammalian auditory system is done in more advanced mammalian taxa. In addition to Zhang he and the beast, the Repenomamus robustus and the Jeholodens jenkinsi were found in the Rehe biota mentioned later, indicating that the mammals of the biota at that time already had a certain degree of differentiation.

Many people know that Zhang He beast was found in the Rehe area of Liaoning, in the years that followed, in fact, Liaoning found many other famous Mesozoic mammals, and the trintual mammal Rehe beast similar in size to Zhang He, the largest mammal reptile in the Mesozoic Era. Even more significant is the Chinese possum, one of the lowest ends of marsupial evolution, archaeopteryx, one of the ancestors of the true beast. It can be seen that the mammals in Liaoning at that time had differentiated into a relatively complex small population. The fossils of Zhang He and the beast are also more important among them, all the features appear to be relatively primitive, and the walking is also a bit of a reptile shadow.

But there is one thing that many people may not know, Zhang He beast may be poisonous, especially the male Zhang He beast, the poisonous part is the spike of the hind foot, as for the toxicity today can not be examined. In fact, the toxicity of Zhang he beasts precisely explains their primitive status in the evolutionary status of mammals. Today's venomous mammals are single-hole platypuses, and venom is also on the tail spines of the hind legs. The family of platypus has evolved in the Mesozoic Era, and today's platypus can still see a lot of shadows compared to old relatives in the Mesozoic Era, almost the most primitive of today's mammals, while the Zhanghe beast, although it does not belong to the single-for-hole order, is also a primitive mammal. Although poisonous, their defenses are not very strong, and digested Zhang He beasts have been found in the fossil remains of small carnivorous dinosaurs, the Chinese dragon bird, and larger carnivores such as dillons pose a huge threat to Zhang He beasts.

Mammals are the animals we are most familiar with, dominating modern terrestrial ecosystems, including our common cats, dogs, horses, cattle, and humans themselves, as well as kangaroos, koalas, and platypus that we don't see. Mammals appeared on Earth almost at the same time as dinosaurs, and their history dates back about 220 million years. In the "age of dinosaurs" in the Mesozoic Era, mammals were small in number and small in number, and were subordinate to the ecosystem. Mammals in the Rehe biota are far less prosperous than other vertebrates such as birds and dinosaurs, but they are important members of the fauna and have a special significance in biological evolution.