Explosive diversification and adaptation to grassland of early Bovini

2019 Fiscal Year Final Research Report

• Project/Area Number: 16K17828
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Stratigraphy/Paleontology
• Research Institution: Kyoto University (2019); Waseda University (2016-2018)
• Principal Investigator: Nishioka Yuichiro 京都大学, 霊長類研究所, 研究員 (00722729)
• Project Period (FY): 2016-04-01 – 2020-03-31
• Keywords: ウシ科 / 哺乳類 / 東南アジア / ミャンマー / タイ / 化石 / 新生代

Outline of Final Research Achievements

To understanding the relationship between environmental change and the diversification of early Bovini in the Neogene of continental Southeast Asia, I systematically examined bovid fossils. The bovid fossil assemblages from three stratigraphic units (ca. 9, 6-4, and 3 Ma) of the late Miocene to Pliocene Irrawaddy beds, Myanmar were classified in order to clear the stratigraphic change of species composition. Moreover, the bovid fossil assemblage from the late Miocene beds (ca. 9-8 Ma) on Tha Chang sandpits, Thailand were described. As results, it became clear that early species of the Bovini in continental Southeast Asia had had a faunal correlation with those in South Asia until 6 Ma, and then some Southeast Asian endemic species had diverged , owing to the increase of faunal separation at the Indo-Myanmar boundary.

Free Research Field

古哺乳動物学

Academic Significance and Societal Importance of the Research Achievements

未解決だった東南アジアの新第三紀ウシ科化石群集の実態を明らかにし、ウシ族の初期進化について生物地理学的観点から検証した。初期のウシ族は草原環境の拡大とともに急激に個体数を増やしたが、種分化や固有種の出現には植生変化よりも地形変化による地理的隔離が強く影響したことを化石記録に基づき証明した。