Podocarpium is an extinct genus of the Fabaceae family with a rich fossil record in Eurasia, dating back to the Eocene. However, the lack of fossil records in some key areas (such as the Tibetan Plateau) has limited scientists' understanding of the species diversity and biogeographic evolution of this genus.
The paleoecological research group of the Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, has long been conducting paleobotanical research in the central Qinghai-Tibet Plateau. In recent years, a new flora, the Xiongmei Flora, has been discovered in the Upper Eocene Niubuo Formation of the Lumpola Basin. The researchers studied the pod fruit fossils found and established a new species through numerical analysis of morphology and geometry - Podocarpium tibeticum W.-C. Li, J. Huang et T. Su sp. nov, its main features that are different from the fossil species published by predecessors of the genus Monospermum are the asymmetry on both sides of the fruit pod, the beak shape of the fruit beak, and the obvious tilt of the fruit base.
Tibetan single-seeded bean is the earliest fossil record of this genus in the Tibetan Plateau. This discovery shows that this genus existed in the central Tibetan Plateau in the late Eocene (35 Ma). Comprehensive analysis of fossil evidence and model simulations suggests that the genus may have originated in East Asia, spread to the Central Valley of Tibet in the late Eocene, and then spread westward to Europe via low-latitude pathways along the island chain of the Neo-Tethys Ocean; The distribution patterns of this genus over geological time are closely related to the history of global climate change. This discovery further supports that the central Tibetan Plateau was an important hub for global Paleogene flora exchange.
Relevant research results, titled Podocarpium (Fabaceae) from the late Eocene of central Tibetan Plateau and its biogeographic implication, were published in Review of Palaeobotany and Palynology to celebrate the 90th birthday of Zhou Zhiyan, a Chinese paleobotanist and academician of the Chinese Academy of Sciences. . The research work is supported by the Strategic Priority Science and Technology Project of the Chinese Academy of Sciences, the National Natural Science Foundation of China, the Second Comprehensive Scientific Research on the Tibetan Plateau, the Youth Innovation Promotion Association of the Chinese Academy of Sciences, and the Yunnan Provincial Natural Science Foundation.
Figure 1. Fossil point appearance of the male plum flora
Figure 2. New fossil of the genus Podocarpium tibeticum discovered in the Lunpola Basin of Tibet - Podocarpium tibeticum; restoration map of the genus A. P. tibeticum sp.nov. ; B. P. eocenicum; C. P. podocarpum.
Figure 3. Principal component analysis and shape variation of fruit shape of the genus Monospermum
Source: Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences
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