On April 25, 2002 (March 13, 2002), the earliest placental mammal fossils were discovered in China. On April 25, 2002, Vice Minister of Land and Resources Shou Jiahua announced in Beijing: The newly discovered fossil of the Protozoan climbing animal in Lingyuan City, Liaoning Province, my country has recently been confirmed to be the world's earliest placental mammal fossil. This provides new fossil evidence for the origin and earliest evolution of true mammalian (placental) mammals. At a press conference held by the Ministry of Land and Resources, Shou Jiahua introduced that the new discovery was jointly completed by scientists from the Institute of Geology of China Academy of Geological Sciences and the Carnegie Museum of Natural History in Pittsburgh, USA. It is estimated that the geological age of the fossils is at least 130 million years old. This new mammal was named by the researchers as the Climbing Progenitor, which means that this mammal fossil is in the most primitive position in the evolutionary system of real animals, placentous mammals, and has limb bones that can be flexibly climbed. Features. According to reports, the newly discovered ancestor beast skeleton is complete and exquisitely preserved. There are delicate impressions of mammalian fur and traces of carbonized soft tissue around the bones. The original beast's body is about 14 centimeters long and its estimated weight is between 200 and 250 grams. The teeth of the ancestor bear many of the most typical defining characteristics of true animals, and the tooth characteristics indicate that it was an insectivorous animal. The shoulder straps, limb bones, and quadruped of the ancestor bear many characteristics unique to modern climbing or arboreal mammals. These characteristics show that the protozoan is a small mammal that is good at climbing rugged terrain and moving in bushes, and lives in short bushes on the banks of rivers and lakes. According to Ji Qiang, chief scientist of the project, other mammals that symbiosis with the newly discovered ancestor include Zhanghe, Jehol and Creeping Animals. The famous Jehe biota in western Liaoning, which produced the ancestor beasts, also contains a variety of exquisite feathered dinosaurs and primitive birds, amphibians, reptiles, fish and a large number of plant fossils. The 1996 "Chinese Dragon Bird" was discovered in this area. The study of the newly discovered ancestor animals by Chinese and American paleontologists and their positioning on the mammalian tree has filled an important gap in the evolutionary history of the earliest primitive true mammals, indicating that the early Cretaceous true mammals The differentiation of true mammals is not only far earlier than previously estimated, but also beyond the previously known and limited early differentiation. Its discovery provides an important basis for studying the molecular evolution speed and comparative study of morphological and functional evolution of placental mammals.