2009年03月19日

Life before the rise of oxgen

The discovery og molecular fossils in 2.7-billion-year-old rocks prompted are-evaluation og microbial evolution, and of the advent of photosynthesis and rize of atmospheric oxgen.

That discovery now comes into question.


Go Back to Archaean time, the interval of Earth's History between about 4 billion and 2.5 bilion years ago, and we're in largely unknown biological territory.

Attenpts to identifly a fossil recorf of life have prodused meager ersults. and controversy presists obout whether certain microfossil-like structuress are of biological orgin.(Schopf,J.W.Phill Trans. R. Soc B.361-869-885/2006)(Brasier,M.D.et.al. Nature416,76-81/2002)

Almost a decade ago, however, Archaean palaeontology received a big boost with the discovery by Brocks et al. of a diverse assenblage og lipid 'biomarkers' in 2.7-billion year-old geological samples from Western Australia.

Biomarkers, or molecular fossils, are natural products (often hydrocarbons) whose synthesis can be linked to a specific biological origin - and, by physiological proxy, to enbiron mental conditions.

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posted by 0≠素子 at 10:29| Comment(0) | biogeochemistry | このブログの読者になる | 更新情報をチェックする
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