Mammalian faunal transition with the early diversification of eutherians in the Early Cretaceous Asia

2019 Fiscal Year Final Research Report

• Project/Area Number: 16K17830
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Stratigraphy/Paleontology
• Research Institution: Ehime University
• Principal Investigator: Kusuhashi Nao 愛媛大学, 理工学研究科(理学系), 准教授 (70567479)
• Project Period (FY): 2016-04-01 – 2020-03-31
• Keywords: 哺乳類 / 進化 / 中生代 / 白亜紀 / アジア

Outline of Final Research Achievements

The project was intended to investigate mammalian faunal transition in Asia during the late Early Cretaceous, when an early diversification of eutherians occurred, I conducted fossil excavations in Fuxin area, Liaoning Province, northeastern China and taxonomic study on mammalian fossils from the Shahai and Fuxin formations.
Based on taxonomic study on newly discovered specimens as well as previously collected specimens, papers describing new species and specimens of eutriconodontans and multituberculates were published. I also published a paper of reexamination of previously described eutherian species. The full picture of the fossil assemblages from the Shahai and Fuxin formations is becoming clearer, and it gradually revealing the mammalian faunal transition in Asia during the late Early Cretaceous.

Free Research Field

古脊椎動物学

Academic Significance and Societal Importance of the Research Achievements

真獣類は現生哺乳類種数の90%以上を占めるグループで，中生代の中期ジュラ紀 (あるいは遅くとも前期白亜紀の中頃まで) に出現後，前期白亜紀の後半には初期の多様化を始めたらしいことが化石記録でわかってきた．真獣類の初期進化の中心であったと考えられるアジアにおいて，真獣類の多様化に伴い哺乳類相の構成がどのように変化したのかを知ることは，哺乳類の進化史を探るうえで重要なテーマである．現在その時代の様子を知ることができる化石群の調査を進めており，徐々に当時のアジアの哺乳類相変遷が明らかになりつつある．