Discovery and significance of giant panda(Ailuropoda melanoleuca) fossil in the Qinling-Daba Mountains Area of Shaanxi Province

The giant panda(Ailuropoda melanoleuca)is a unique and rare animal in China and the flagship species for global biodiversity conservation. Nowadays, giant pandas are merely distributed in Sichuan, Gansu and Shaanxi Provinces. However, fossil evidence indicates that they were widely distributed throughout Southern China and in some areas of North China during the Pleistocene. The Qinling-Daba Mountains area(31° 42'~34° 45' N, 105° 29'~111° 15' E)of Shaanxi Province is not only an important distribution region for the extant giant pandas in China, but also a crucial region for the evolution of giant pandas during the Pleistocene. However, the previous fossil materials of giant panda in this region were scarce and incomplete, and no skull or postcranial skeleton was found. In July 2024, we obtained a relatively intact skull of giant panda from Chenggu County, Hanzhong City, Shaanxi Province. Moreover, under the guidance of the local villagers, we confirmed the residual postcranial skeletons of the giant panda from a karst cave called Mangshe cave in the Wuliba Village, Erli Town of Chenggu County. The postcranial skeletons are connected with joints, which indicates that they were preserved in situ without transportation. It is the first time that a relatively intact giant panda fossil with skull and postcranial skeletons is discovered in the Qinling-Daba Mountains area of Shaanxi Province. The present study provides a preliminary report on the giant panda fossil from Mangshe cave, analyzes its burial characteristics combined with cave features, and carries out AMS 14C dating of the giant panda and discuss its living background. Based on morphological characteristics and comparison of teeth measurements, the giant panda from Mangshe cave can be preliminary assigned to A.melanoleuca baconi, which might be belong to a sub-adult individual, approximately 3~4 years old. There are favorable conditions for the preservation of the giant panda from Mangshe cave due to its special cave environment. Based on the investigation of the cave system and the preservation feature of the postcranial skeletons, the appearance of the giant panda in Mangshe cave might be due to accidental falling and dropping along the sinkhole into the connecting Mangshe cave. The AMS 14C dating result of the giant panda is 33438~32118 cal.a B.P., which indicates that the living age of the giant panda corresponds to the late stage of Marine Isotope Stage 3(MIS 3a). The climate was quite warm and humid during that period, which facilitated the giant panda population dispersal in the Qinling Mountains of Shaanxi Province and its appearance in Chenggu County. The giant panda from Mangshe cave in Chenggu County is the most intact and closest to the present day with the definite dating result, and is also the northernmost and most complete giant panda fossil record in China, which provides rare material for understanding the survival and evolution history of giant pandas in the Qinling-Daba Mountains area of Shaanxi Province and is of great significance to explore the origin, evolution and relationship between A.m. qinlingensis and A.m. melanoleuca. In the future, systematic morphological study, ancient DNA analysis and high precision CT scan will be carried out on the giant panda fossil from Mangshe cave to provide more scientific basis for revealing the origin and evolution process of A.m. qinlingensis and its relationship with other regional giant panda populations.