by Tao Su
Dr. Tao Su is an associate professor and principle investigator with the Paleoecology Research Group of the Xishuangbanna Tropical Botanical Garden in Yunnan, China. He recently visited the paleobotany collections at the Florida Museum to compare his specimens from the Tibetan Plateau to similarly aged specimens in the US for identification.
The Tibetan Plateau, about 250 million km2 with average altitudes of more than 4000 m, is called ‘the Third Pole’ in the world. The collision between the Indian Plate and the Eurasian Plate shaped the topography of this large region. The evolution of this plateau greatly influenced the topography of Asia, as well as the regional, and even global, climate patterns. Plant fossils are pivotal for us to understand the biodiversity history and evolution of the plateau in the geological past, however, fossil floras in this area have been far from fully investigated because of access and logistical difficulties.
During recent years, we have done plenty of fieldwork in the central part of the Tibetan Plateau, which has average elevations of around 5000 m. Several Paleogene floras have been found for the first time, which provide a good opportunity to understand the biodiversity history in this fascinating region. Among these floras, the early-middle Eocene Jianglang flora in Bangor County is high in plant diversity, with plant fossils in the forms of fruit/seed, leaf, tuber and flower being preserved. Very interestingly, it shares many floristic components to flora from the Eocene Green River Formation in the Western Interior USA, such as Lagokarpos (unknown family) and Illigera (the family Hernandiaceae), indicating a close floristic relationship between the Tibetan Plateau and North America as early as ~45 Ma. Another site in the Lunpola basin, namely late Oligocene Dayu flora, is well known for its palm and grass fossils. The length of a palm leaf specimen is up to 1 m, even not preserved as whole. Additionally, plenty of grass fossils were collected from the same layer, though it is still unresolved if they are C4 or C3 plants. Meanwhile, this site in Lunpola basin is also famous for animal fossils, such as climbing perch (Eoanabas thibetana) and rhino (Plesiaceratherium).
Generally, these new fossil materials collected from the core area of the Tibetan Plateau show quite high biodiversity in the central part of the plateau. They open a new window to exploring the process and mechanism of biodiversity history under dramatic paleoenvironmental changes in the plateau during the geological past. Many more interesting fossils are expected to be found in future.
Questions for Dr. Tao Su? Email [email protected].
To learn more:
Read about the Green River formation here
This paper published in Nature explains more about the paleogeography and paleoenvironment of the Tibetan Plateau during the late Oligocene.