Analysis Of Dental Enamel Carbon And Oxygen Isotopes Of The Early Holocene Mammal Fauna In Tangzigou, Baoshan, Yunnan Province

The Tangzigou fossil site (25° 1′ 31.22″ N, 99° 0′ 28.04″ E) which covers an area of over 1000 m2 and has an altitude of approximately 1350 m a. s. l., is located on a small hill about 100 m east of Tangzigou Village, which belongs to Pupiao Town, Baoshan City, in the northwest of Yunnan Province, China. Tangzigou fossil site has undergone multiple archaeological excavations and yielded a large number of ancient biological fossils. This study takes 107 ancient mammalian teeth fossils from the Early Holocene (about 8740 cal.a B. P.) at Tangzigou fossil site including Bovidae (n=42), Cervidae (n=48), Rhinocerotidae (n=6), Ursidae (n=3) and Suidae (n=8) plus 7 teeth from Bubalus bubalis in the Baoshan area as the research objects. We conducted X-ray diffraction analysis on the tooth enamel to ensure its purity. Systematic enamel carbon and oxygen isotope analyses were conducted to reconstruct the dietary and habitat characteristics of the Tangzigou fauna in the Baoshan area of Yunnan and to reflect the hunting environment of the ancient "Pupiao people". Carbon isotope analysis shows that Rhinocerotidae (- 13.6 ‰ ±1.0 ‰) lived in relatively closed dense forest belts and their diet was almost entirely composed of C3 plants; The δ13C values of Bubalus bubalis (- 8.1 ‰ ±0.7 ‰) are significantly positive, which is a result of human feeding with C4 plants. Some bovids and cervids have δ13C values within a similar range, indicating that they consumed a considerable amount of C4 plants and were likely to have lived in the C3/C4 mixed areas at lower altitudes. The δ13C distribution range of Bovidae (- 10.7 ‰ ±2.8 ‰) and Cervidae (- 12.2 ‰ ±2.5 ‰) was relatively large, indicating that they had a wide range of altitudes or habitats; omnivorous Suidae (- 12.0 ‰ ±0.6 ‰) and Ursidae (- 11.5 ‰ ±1.2 ‰) had relatively higher δ13C means than Rhinocerotidae (- 13.6 ‰ ±1.0 ‰) which almost entirely consuming C3 vegetation, suggesting that these animals may lived in relatively open habitats or lived at the edge of forests and consumed a small amount of C4 plants. Oxygen isotope analysis indicates that Bovidae (-11.0 ‰ ±1.9 ‰) and Rhinocerotidae (- 12.0 ‰ ±0.8 ‰) mainly relied on water pools and streams formed by atmospheric precipitation; Cervidae (- 10.6 ‰ ±2.0 ‰) had a higher proportion of water intake from plant leaves and had a wide range of altitudes; Ursidae (- 11.1 ‰ ±2.6 ‰) may have shared the same water sources as Bovidae (- 11.0 ‰ ±1.9 ‰). Suidae (- 11.7 ‰ ±2.4 ‰) mainly drank from water pools and streams, but also included water from plant leaves. Sequential carbon and oxygen isotope measurements were conducted on 10 hypsodont teeth (> 7 cm) of Bovidae at Tangzigou, and the interdecadal carbon and oxygen isotope change curve was obtained. The results show that these individuals may have been distributed in multiple habitats at different altitudes. Individuals living in the C3/C4 mixed area at lower altitudes recorded the seasonal changes of their habitats in their enamel carbon and oxygen isotopes completely, while individuals mainly consuming C3 vegetation showed insignificant seasonal changes in their enamel carbon and oxygen isotopes. Some individuals may have exhibited vertical migration behavior with the change of seasons. Through the analysis of the distribution range and habitats of the Tangzigou fauna, it is inferred that the Late Pleistocene "Pupiao people" had advanced hunting skills, a wide range of hunting altitudes, and a preference for hunting Bovidae and Cervidae. The natural environment near the Tangzigou site at that time was characterized by a wide Pupiao ancient lake, with a large number of Cervidae and Bovidae widely distributed in mountain forests and low-altitude grasslands, while Ursidae and Rhinocerotidae lived in mountain dense forests and Suidae lived at the forest edge.