西澳发现34亿年前最古老化石

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科学家发现34亿年前微生物化石
  
英国《自然—地球科学》杂志网站8月21日刊登研究报告说，澳大利亚和英国科学家在澳大利亚西部发现了34亿年前的微生物化石，这是世界上迄今发现的最古老的化石。

西澳大利亚大学和牛津大学的研究人员报告说，这些化石中的微生物有细胞状的结构。另外，化石中还含有古微生物排泄物的遗迹——黄铁矿。34亿年前，地球上缺少氧气，微生物的食物是含硫化合物，而黄铁矿是微生物新陈代谢后的产物。

参与研究的英国牛津大学教授马丁·布拉西耶说，这些化石形成前，当地曾发生火山喷发。形成后，当地再次发生火山喷发。两次火山喷发后形成的保护层不仅防止化石被破坏，而且为科学家提供了判断化石形成时间的依据。

根据两次火山喷发的时间，科学家测定这批化石的年龄为34亿年。

发现这批化石对于研究生命起源具有重要意义。此前，科学家推测，在约35亿年前，地球上就已经存在生命，但长期没有找到化石证据。（来源：新华网 黄堃）



Microfossils of sulphur-metabolizing cells in 3.4-billion-year-old rocks of Western Australia
Sulphur isotope data from early Archaean rocks suggest that microbes with metabolisms based on sulphur existed almost 3.5 billion years ago, leading to suggestions that the earliest microbial ecosystems were sulphur-based1, 2, 3, 4, 5. However, morphological evidence for these sulphur-metabolizing bacteria has been elusive. Here we report the presence of microstructures from the 3.4-billion-year-old Strelley Pool Formation in Western Australia that are associated with micrometre-sized pyrite crystals. The microstructures we identify exhibit indicators of biological affinity, including hollow cell lumens, carbonaceous cell walls enriched in nitrogen, taphonomic degradation, organization into chains and clusters, and δ13C values of −33 to −46‰ Vienna PeeDee Belemnite (VPDB). We therefore identify them as microfossils of spheroidal and ellipsoidal cells and tubular sheaths demonstrating the organization of multiple cells. The associated pyrite crystals have Δ33S values between −1.65 and +1.43‰ and δ34S values ranging from −12 to +6‰ Vienna Canyon Diablo Troilite (VCDT)5. We interpret the pyrite crystals as the metabolic by-products of these cells, which would have employed sulphate-reduction and sulphur-disproportionation pathways. These microfossils are about 200 million years older than previously described6 microfossils from Palaeoarchaean siliciclastic environments.

作 者：David Wacey; Matt R. Kilburn; Martin Saunders; John Cliff; Martin D. Brasier
期刊名称： Nature Geoscience
期卷页： 2011-08-21 第卷 第期 ~页
学科领域：地球科学 » 地质学 » 古生物学和古生态学
添加人是否为作者: 否
原文链接：http://www.nature.com/ngeo/journ ... /full/ngeo1238.html
DOI： doi:10.1038/ngeo1238
ISBN： 1752-0894

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澳洲人也研究这个