Biostratigraphic distribution of marine vertebrates in the Japanese Upper Cretaceous

2022 Fiscal Year Final Research Report

• Project/Area Number: 18K03822
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 17050:Biogeosciences-related
• Research Institution: Kanagawa University (2022); Tokyo Gakugei University (2018-2021)
• Principal Investigator: Sato Tamaki 神奈川大学, 理学部, 教授 (90466912)
• Project Period (FY): 2018-04-01 – 2023-03-31
• Keywords: 白亜紀 / 化石 / 爬虫類 / 魚類

Outline of Final Research Achievements

The purpose of this study was to find out whether the timings of diversification and/or extinction events differ in different regions or not by comparing the fossil vertebrates of the Upper Cretaceous. Fieldworks on the Upper Cretaceous strata of the Nemuro, Saroma, and Yezo Groups in northern, eastern , and central Hokkaido were conducted, and collections of local and national museums were studied. Although small in number, additional specimens of fossil invertebrates and vertebrates were collected during the fieldwork. Studied on the museum collections revealed the presence of previously unknown/undescribed specimens, and the descriptive studies of the fish and reptiles, in particular those of selachian and pliosaurid plesiosaurs, demonstrated the similarity and/or difference in the taxonomc composition and/or stratigraphic distribution of some taxa in the Upper Cretaceous in Hokkaido and those in other areas of Japan and outside the country.

Free Research Field

古生物学

Academic Significance and Societal Importance of the Research Achievements

後期白亜紀には様々な魚類や海生爬虫類が生息していたが、本邦の化石記録は分類群による先行研究の偏りが大きい。魚類化石は先行研究が極端に少なく、爬虫類化石はノジュールに含まれる断片的な標本が多いために、専門家が見なければ何の化石かわからないことも多い。本研究により、本邦で未報告の分類群を含む魚類・爬虫類の存在が明らかになり、層序分布を世界の他の地域と比較したことにより、白亜紀後期の海生脊椎動物化石相の地域差を比較できるようになった。また、地方自治体や大学等の博物館が長年にわたり地道に管理してきた自然史標本の学術的価値を示すという社会的な意義があると考える。