Rehe Biota and Yanliao Biota: Fossil Interpretations of The Life History of the Mesozoic Earth

The 4.6 billion-year-old Earth has bred countless lives, but how did the earliest life on Earth come about? The sea, land, and sky are the space on which life depends, and the ocean is the cradle of life, but how does life climb from the ocean to land? Life on land yearns for the sky, whether it is reptiles, birds or mammals, flying is their dream, but how does life on land fly into the blue sky? Humans are outstanding representatives of mammals, the primates of all things, but how did the first humans evolve? The study of this series of questions requires scientific answers, but science is evidence-oriented, what is the evidence for these questions? Where are they?

The evidence for the answer is the discovery of fossil paleontological organisms. What is a fossil? The so-called fossils are the remains and remains of prehistoric earth life that have been petrified in the strata, as well as the remains and relics of their activities, and the formation of fossils requires specific geological and historical conditions and burial conditions.

So where were the fossils found? Fossils have been found in many parts of the world, and they are preserved in sedimentary strata without exception. Important fossil discoveries in China include the Cambrian Chengjiang fauna represented by the Chengjiang area of Yunnan and the Qingjiang fauna of the Cambrian Period represented by the Yichang region of Hubei Province, the Silurian Xiaoxiang fauna represented by the Qujing region of Yunnan, the Triassic Guanling fauna represented by guanling and other areas in Guizhou, the Jurassic Yanliao biota and the Cretaceous Rehe biota represented by western Liaoning and its adjacent surroundings, the Cenozoic hezheng fauna represented by the Hezheng region of Gansu, and the Cenozoic Shanwang biota represented by Linqu in Shandong. It can be said that these important fossil biota discoveries provide important evidence for the evolution of life on Earth. Among them, the fossils found in the Rehe biota and later the Yanliao biota provide detailed evidence for the origin of birds and the origin of birds flying, the evolution of feathered small theropod dinosaurs, the origin and radiation of several pterosaur taxa, the origin of early mammals, and the origin and evolution of angiosperms.

From the first fossil wolffin fish of the Rehe biota more than 100 years ago was discovered by the French anatomist Sovas in Lingyuan, Liaoning Province, China, from the concept of "Rehe System" and "Rehe Fauna" proposed by the famous American geological paleontologist Professor Greep nearly 100 years ago, to the 1960s when Chinese geological paleontologist Gu Zhiwei improved the "Rehe Group" and "Rehe Biota", from the discovery of the Three Pagoda Chinese Birds and the Yandu Huaxia Bird 30 years ago. The Rehe biota and Yanliao biota, which have been silent for nearly a hundred years, have attracted great attention from paleontologists in China and even the world, and have always been the hot spot and frontier of international paleontological research.

Through more than 100 years of continuous discovery and research by Chinese and foreign paleontologists, the face of the Rehe biota has changed from the past, and this silent land centered on Western Liaoning has been full of vitality through continuous excavation and study by paleontologists, and its representative fossils are far from being simply summarized by the three representative molecules of the "Oriental Leaf Limb Introduction - Three-tailed Ephemeral - Wolffin Fish" of that year. So far, the Rehe biota and the Yanliao biota have been found in many phylae, such as gastropods, bivalves, crustaceans and insects, etc., non-jawed, bony fish, teleost fish, amphibians (tailless and tailed amphibians), reptiles (turtles and turtles, lizards, pterosaurs, ornithopods and lizards), birds (basal birds, anti-birds and birds of the day), and mammals (polyodontopods, barodonts, true tricornals, post-mammals and eumorphic mammals), as well as major plant phylums such as algae, mosses, ferns, gymnosperms, and angiosperms, up to thousands of species.

The fossils of the Rehe biota and the Yanliao biota almost include many biological categories that transitioned from the Mesozoic to the Cenozoic, providing an extremely valuable fossil basis for studying major theoretical issues such as the origin of the Mesozoic terrestrial biota, the origin of birds (including the origin of feathers and flight), the origin of mammals, and the origin of angiosperms. As a result, the Rehe biota has been hailed as "one of the most important paleontological discoveries of the 20th century". The Rehe biota and yanliao biota centered on the western Liaoning region are world-class fossil treasure houses. The study of the origin and evolution of various biological groups (including many important vertebrate taxa) and the origin and evolution of some important biological structures (such as feathers, mammalian middle ear, etc.) are of great evolutionary biological significance. Today, our understanding of the Era of the Rehe Biota and the Yanliao Biota is also far from being comparable to the past, and it is very clear, but the study of biological evolution and environmental background is still being explored. In addition, the different taxa of the Rehe biota and the Yanliao biota include a number of important evolutionary transitional biological types, providing important fossil evidence for Darwin's theory of evolution.

However, there is no end to science. Why did dinosaurs grow feathers during this period of the Rehe biota and the Yanliao biota, and then evolve into birds? Why did Pterodactyl evolve from "Beak-billed" to Pterodactyl? Why are there a large number of angiosperms in this period? Although everyone knows that the Jurassic and Cretaceous periods were very important periods in the history of the earth's development, and the global paleogeographic pattern and paleoclimate conditions underwent major changes, we do not know what major events occurred at that time that led to such great changes in the biological world, which are worth further exploration. At present, the National Natural Science Foundation of China Basic Science Center project "Craton Destruction and Terrestrial Biological Evolution" aims to answer this question.

The author is a group of paleontologists who love the Rehe biota and the Yanliao biota, and over the years they have been diligently pursuing and keeping an eye on the latest discoveries and research progress of the two biota, not only obtaining relevant information from professional journal papers, but also further understanding the fossil discovery research process from in-depth reports of domestic and foreign news media. Based on the chronological sequence of more than 100 years since the discovery of the Rehe biota, from the first fossil Dai's wolffin fish in 1880 to the petite accident bird discovered in 2020, they wrote a total of 70 or 80 fossils of the two most representative biota, which can be called the chronicle of the discovery and research of the Rehe biota and the Yanliao biota. This book writes about the significance and scientific value of the discovery of the Rehe biota and the Yanliao biota from the journalistic perspective of paleontological fossil enthusiasts. Most of the fossil discoveries and research it has included have been published in authoritative scientific journals and have attracted great attention in the scientific community and mass media, such as the British "Nature", the American "Science" and the "Proceedings of the National Academy of Sciences" of the United States. The articles on the Rehe biota and Yanliao biota included in the article were written by referring to relevant news materials based on the fossils that have been studied and published. It is also not a general news report that can be understood by adult readers without professional knowledge.

This book closely focuses on the discovery of the main fossils of the Rehe biota and the Yanliao biota and the research timeline of the fossils, providing readers with a panoramic depiction of the Rehe biota and the Yanliao biota. Since the authors and editors are not professional paleontologists, mistakes and inadequacies are inevitable, but their love for paleontology is commendable, and readers are invited to criticize and correct them in their reading. is the preamble.

Wang Xiaolin (Researcher, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Foreign Academician of Brazilian Academy of Sciences)