Located at the northeastern margin of the Qinghai-Xizang (Tibetan) Plateau, the Qaidam Basin serves as a key region for studying Mesozoic terrestrial ecosystem evolution and exploration of fossil energy resources.Since the 1950s, abundant paleobotanical and palynological findings have been accumulated from the Lower-Middle Jurassic in this region. However, as a crucial proxy of paleobotanical research, fossil woods have rarely been documented in the Jurassic strata of the Qaidam Basin, and the systematic studies remain insufficient. This knowledge gap has hindered comprehensive analysis of Mesozoic paleovegetation evolution and climatic and environmental changes in the area.
Recently, a Sino-German joint research team on paleobotany, led by Professor Wang Yongdong from the Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences (NIGPAS), Dr. Xie Aowei from Senckenberg Research Institute, Germany (SRI), and Prof. Tian Ning from the College of Paleontology of Shenyang Normal University (CPSNU) discovered a new type of exceptionally well-preserved fossil wood material in the Early Jurassic strata dating back about 186 million years ago on the northeastern margin of the Qaidam Basin. They carried out systematic anatomical studies, confirmed its taxonomic attributes and revealed its significance for paleobiogeography and paleoclimate research.
Anatomical studies have shown that fossil exhibits araucarian radial tracheid pits, each cross-field usually bearing 1–2 podocarpoid pits, taxodioid pits or oopores, abundant septa in tracheids, and all ray cell walls thin and unpitted. These morphological features support its classification into the extinct conifer plant genus Metapodocarpoxylon Dupéron-Laudoueneix et Pons.
Since 1985, the genus Metapodocarpoxylon has been establishedfor over 40 years. Previously records of this genus are restricted to the northern Gondwana during the Mesozoic, and their localities are documented in over 40 localities forming a distinctive latitudinal belt extending westwards from Lebanon to Peru in the Jurassic and Cretaceous sediments. The current discovery not only represents its first record in Laurasia but also expands its biogeographic range from northern Gondwana to Laurasia, defying conventional biogeographic boundaries. This report has broken through the traditional understanding of geographical distribution of Metapodocarpoxylon, and contributes to a deeper understanding of the migration and evolution patterns of this plants in the geological history.
Fossil records shows that Metapodocarpoxylon mainly appeared from the Middle Jurassic to the Cretaceous period. This study reveals that the genus might have originated in Laurasia during the Early Jurassic and then migrated to the Gondwana region under the influence of climate change. The new fossil materials discovered in the Qaidam Basin have pushed the fossil record of this genus back from the previously known Middle Jurassic to the Early Jurassic (about 20 million years earlier).
The fossil wood of Metapodocarpoxylon displays distinct growth rings, with abundant, well-formed earlywood and narrow latewood, as well as abrupt transitions between earlywood and latewood. This observation, along with previous interpretations based on macroflora, palynoflora and sedimentological data, suggests that a warm and humid climate condition with mild seasonality prevailed in the region during the Early Jurassic.
Integrated analysis of palaeobotanical and sedimentological data further indicates that the Qaidam Basin experienced a warm-humid climate with mild seasonal precipitation disparities, providing optimal conditions for dense coniferous forests. This conclusion aligns with palaeobotanical and palynological evidence supporting a "conifer-dominated temperate humid climate," thereby furnishing critical evidence for reconstructing palaeovegetation and refining Early Jurassic climatic models in East Asia.
This research has been published in the Cambridge University international journal Geological Magazine. Prof. Yongdong Wang from NIGPAS, Dr. Aowei Xie from SRI and Prof. Ning Tian CPSNU served as co-corresponding authors. The international collaborative team included Prof. Dr. Dieter Uhl (Senckenberg Research Institute), Dr. Min Xu, Dr. Yanbin Zhu, Dr. Li Zhang, Dr. Xiao Teng, and doctoral student Hongyu Chen from NIGPAS. This research received joint support from the National Natural Science Foundation of China, the Strategic Priority Research Programs (Category B) of Chinese Academy of Sciences, and the State Key Laboratory of Palaeobiology and Stratigraphy.
Reference: Xie, A.*, Chen, H., Wang, Y.*, Tian, N.*, Xu, M., Zhu, Y., Zhang, L., Teng, X., Uhl, D. 2024. An exceptionally preserved conifer wood Metapodocarpoxylon from the Jurassic of northeastern Qinghai-Xizang (Tibetan) Plateau, and its palaeobiogeographic and palaeoclimatic significances. Geological Magazine, 162(e7): 1–10. https://doi.org/10.1017/S0016756824000451
Fig. 1 Anatomical characters of Metapodocarpoxylon wood from the Lower Jurassic in the Qaidam Basin. (a–c), cross sections; (d–h), radial sections.
Fig. 2 Anatomical characters of Metapodocarpoxylon wood from the Lower Jurassic in the Qaidam Basin. (a–d), radial sections; (e–i), tangential sections.
Fig. 3 Palaeobiogeographic map showing the spatio-temporal distribution of Metapodocarpoxylon worldwide
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