The birthplace of putative multicellular organisms in the Paleoproterozoic

2018 Fiscal Year Final Research Report

• Project/Area Number: 16K17826
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Stratigraphy/Paleontology
• Research Institution: Tokyo Institute of Technology
• Principal Investigator: Sato Tomohiko 東京工業大学, 地球生命研究所, 研究員 (80714831)
• Research Collaborator: Edou-Minko Ambroise ガボン・マスク工科大学, Prof. ; Moussavou Mathieu ガボン・マスク工科大学, Prof.
• Project Period (FY): 2016-04-01 – 2019-03-31
• Keywords: 前期原生代 / ガボン / 真核生物 / 層序

Outline of Final Research Achievements

This study conducted the geological fieldworks in Gabon, and investigated the detailed litho-, bio-, and chemo-stratigraphy of the Paleoproterozoic sedimentary basins that yields the putative oldest eukaryotic fossils. The depositional environment of the fossil horizons in the Franceville Basin was clarified to be relatively anaerobic. The local high-radiation setting by the uranium-concentrated bed possibly accelerated the evolution of eukaryotes. In the Lastoursville Basin, the continuous δ13Ccarb stratigraphy was newly established, and a negativeδ13Ccarb shift was identified across the fossil appearance. This negative shift may correspond to the terminal Lomagundi Excursion and suggests that the appearance of eukaryotes dramatically changed the global oceanic carbon cycle.

Free Research Field

地球史

Academic Significance and Societal Importance of the Research Achievements

原核生物 (バクテリア, アーキア) から真核生物への進化は, 地球史における最も大きな進化の一つである. その進化が, いつどのような環境下で起きたのか明らかにするためには, 最古の真核生物化石が産する地層から当時の環境を解読することが不可欠である. 本研究で明らかにした, 局所的な高放射線場や, 地球規模の炭素循環変動と真核生物出現の関係は, 地球科学のみならず生物学において, 生物進化の必要十分条件を解明するための鍵となると期待される.