Plant Diversity ›› 2024, Vol. 46 ›› Issue (01): 101-115.DOI: 10.1016/j.pld.2023.03.007

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Megafossils of Betulaceae from the Oligocene of Qaidam Basin and their paleoenvironmental and phytogeographic implications

Tao Yanga,b, Jia-Hao Caia, Yan-Zhi Daia, Hong-Yu Chena,c, Lei Hana, Li Zhangc,d, Wei-Yu Lianga, Xu-Jun Lia, Wen-Jia Lia, Jing-Yu Wua, San-Ping Xiea, De-Fei Yana,c   

  1. a. School of Earth Sciences and Key Laboratory of Mineral Resources in Western China (Gansu Province), Lanzhou University, Lanzhou 730000, China;
    b. Key Laboratory of Vertebrate Evolution and Human Origins of Chinese Academy of Sciences, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing 100044, China;
    c. State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology and Center for Excellence in Life and Paleoenvironment, Chinese Academy of Sciences, Nanjing 210008, China;
    d. Center for Research and Education on Biological Evolution and Environments, School of Earth Sciences and Engineering, Nanjing University, Nanjing 210023, China
  • Received:2022-09-19 Revised:2023-03-17 Online:2024-01-25 Published:2024-03-02
  • Contact: De-Fei Yan,
  • Supported by:
    We thank to Dr. Junling Dong (Chengdu University of Technology, Chengdu), and Dr. Pengju He (Lanzhou University, Lanzhou) for substantial suggestions; Dr. Haylin Chan and Pallas Cate (Sun Yat-sen University, Guangzhou) for helpful remarks and assisting with English; Prof. Steven R. Manchester (University of Florida, U.S.A.) for providing helpful suggestions and literature; Dr. Jianwu Li, Mr. Bing Wang (Xishuangbanna Tropical Botanical Garden, Mengla), and Prof. Trevor Hodkinson (Trinity College, Ireland) for providing some extant specimens of Carpinus and Betula. We sincerely thank Dr. Bian Wang (IVPP, Beijing) for improving the language. This research was conducted under the China Postdoctoral Science Foundation (No. 2022M723151); the Second Tibetan Plateau Scientific Expedition Research Program (No. 2019QZKK0704); the National Natural Science Foundation of China (No. 42172005, 41272026, 41972008, 31870200); and the Strategic Priority Research Program (B) of the Chinese Academy of Sciences (XDB26000000).

Abstract: Understanding the paleoenvironment and phytogeographical history of the Tibetan Plateau, China relies on discovering new plant fossils. The Qaidam Basin has long been regarded as an ideal ‘field laboratory’ to investigate the paleoclimate and paleobiological evolution of the northern Tibetan Plateau. However, fossil angiosperms from the Qaidam Basin are rare, and our knowledge of its paleovegetation is poor. Here, we report fossil leaves and fruits of Betulaceae found from the Oligocene Shangganchaigou Formation of northwestern Qaidam Basin (Huatugou area). Comparative morphological analysis led us to assign the fruits to the Betula subgenus Betula and the leaves to Carpinus grandis. These findings, together with other reported fossil plants from the same locality, reveal a close floristic linkage between the Qaidam Basin and Europe during the Oligocene. The northern pathway of this floristic exchange may have crossed through the Qaidam Basin during the late Paleogene. This floristic linkage may have been facilitated by the continuous narrowing of the Turgai Strait and stronger westerlies, which transported moisture and provided favorable climatic conditions. Indeed, fossil plants collected from the Qaidam Basin suggest that during the Oligocene this region had warm and humid deciduous broad-leaf forest, which differs from the region’s modern vegetation and indicates that the Qaidam Basin may have been a suitable region for these plants to flourish and spread during the Oligocene.

Key words: Paleoenvironment, Biogeography, Betulaceous fossil, Qaidam basin, Tibetan Plateau, Oligocene