Recently, Liu Jun, the research group of the Institute of Vertebrate Paleontology and Paleoanthropology of the Chinese Academy of Sciences, reported on the National Science Review the latest discovery and research results of the early Permian quadruped footprint fauna - Mentougou Footprint Fauna, which is located in the suburbs of Beijing, providing a new clue for the time when the North China plate is connected to the pan continent. The newly discovered Mentougou footprint animal group comes from the early Permian period, about 300 million years ago, and includes dozens of footprints of different shapes and sizes. The study identified at least two major types of footprint records, including ancient amphibians (fragmented vertebrae) and amniotes (sub reptiles or true reptiles), making it the earliest known quadrupedal fossil record in the North China Plate. The main quadrupedal footprints of the Mentougou Footprint Group, including amphibian and amniote footprints, were found in the early Permian period. Terrestrial quadrupedal animals had already spread across the continent, and there are abundant fossil records in Europe, North America, and North Africa today. However, there is still no conclusive fossil record in northern China (North China Plate). The newly discovered Mentougou fauna fills the gap of quadrupedal animals in northern China during the Early Permian period. More importantly, the discovery of the Mentougou Footprint Fauna proves that the North China Plate and the Pangaea were already connected in the early Permian, providing us with a new paleogeographic model for studying the tectonic history, paleontology, and paleoclimate of the Late Paleozoic. The animal composition of this animal group is highly consistent with that of the animal group on the main body of the Pan continent during the same period, indicating that the Mentougou animal group is likely to have migrated and spread from the Pan continent through animal groups. This further suggests that there was a migration channel connecting the North China Plate and the main body of the Pan continent in the early Permian period. Although ice age land bridges and bamboo raft drifting may become migration routes for single animals, especially small animals, the diffusion of animal populations of different sizes and species, and the connection between two continents, is the simplest and most likely explanation in biogeography. Pangaea was a supercontinent that existed on Earth during the Late Paleozoic Mesozoic era, and all the continents today were merged into one at that time. Pangaea was formed in the late Paleozoic era, and the North China Plate located on its eastern edge was an "island" in the early Paleozoic era. It then merged with the Tarim Plate and connected to the main body of Pangaea, but the specific time of connection has been controversial. In addition, the Mentougou fauna provides the earliest record of amniotes in East Asia and is of great significance in the field of biological evolution. Amniotic animals (including extant reptiles, birds, and mammals) are truly terrestrial organisms that do not require a water environment for reproduction. They are one of the most important components of terrestrial ecosystems, and their appearance and early evolution are believed to be closely related to the formation of the supercontinent. The earliest amniotes were born on the western edge of the supercontinent 320 million years ago, with a body similar to lizards. They rapidly radiated and evolved over the following 20 million years. In the early Permian period, they had already differentiated into various carnivorous and herbivorous species with different morphologies, such as reptiles and infraforaminifera, and were distributed throughout the supercontinent. There is a lack of early records of amniotes in northern China, and it was not until the Middle Permian, about 30 million years later, that the highly diverse Dashankou animal group was preserved in Yumen, Gansu. However, this animal group has already made significant progress, with a significant lack of evolutionary history in between. The footprints of amniotes in the Mentougou animal group are relatively primitive, and it is speculated that they were left by early reptiles or true reptiles, which is very different from the amniotes in the Dashankou animal group. During this period of 30 million years, there should have been a hidden replacement of animal populations, which occurred approximately 270 million years ago during the Olsen extinction event. The first author of this study is Chen Jianye, and the co corresponding authors are Chen Jianye and Liu Jun. The research was supported by the Chinese Academy of Sciences strategic pilot project and international cooperation project. (New Society)