International Biogeoscience Conference 2013, Nagoya, Japan
Revealing the biotic diversity of the early earth and the evolution of cyanobacteria and eukaryotes
Main Session Themes
1) Fossil and sedimentary evidence for early eukaryotes and photosynthetic bacteria
2) Geochemical evidence for biotic diversity and metabolisms of early life
3) Insights from modern life to the early evolution of life
4) New techniques and methodologies in Precambrian research
5) Overview of environments and life in the Precambrian
Prof. Roger E. SUMMONS (Massachusetts Institute of Technology, USA)
Prof. Akihiko YAMAGISHI (Tokyo University of Pharmacy and Life Sciences, Japan)
Prof. Isao INOUE (University of Tsukuba, Japan)
This conference aims to bring together geologists, paleontologists, geochemists, biologists, and molecular and evolutionary biologists to discuss significant contemporary issues relating to our understanding of the early evolution of life and its interaction with Earth’s surface environments.
In the past 10 years, evidence has been accumulating for the early evolution of complex ecosystems and biotic diversity during the Archean. Biosignatures including cellular fossils, carbon isotopic values of kerogen, molecular biomarkers such as lipids and hopanes, and microbialites such as stromatolites and microbially-induced sedimentary structures in siliciclastic settings, have been reported from number of sedimentary successions deposited in environments ranging from deep-sea hydrothermal vent systems to coastal sandy intertidal flats, and even from volcanic rocks. It is believed that by 3.0 Ga microorganisms were flourishing in multiple environments. However, these early ecosystems and the biological affinities of reported fossils are poorly understood. Although the signatures of photosynthetic microorganisms can be traced back to 3.4 Ga, the timing of the origin of oxygenic photosynthesis is still unclear. Also problematic, are the recently reported spheroidal and lenticular cellular microfossils larger than 20µm (up to 200 µm) in diameter. They are reported from 3.0, 3.2 and 3.4 Ga sedimentary successions including chemically precipitated cherts and siliciclastic sediments in South Africa and Western Australia. Their large size，organic-wall style of preservation and morphologies suggest they may represent early eukaryotes. This is consistent with the results of biomarker and molecular clock studies that suggest the evolution of cyanobacteria and eukaryotes prior to 2.7 Ga, although it is generally accepted that oxygenation of the atmosphere occurred much later, and widely accepted fossil evidence for eukaryotes dates only from 1.8 Ga. This conference is thus intended to present us with a timely opportunity to discuss these and related issues.
Malcolm R. WALTER
Martin J. VAN KRANENDONK
Graduate School of Environmental Studies, Nagoya University
Australian Centre for Astrobiology, University of New South Wales
Nagoya City Science Museum
School of Informatics and Sciences, Nagoya University
Nagoya University Museum
Japan Astrobiology Network Association
See the attached flyer for more information.