Evolution of Precambrian life in the Brazilian geological record
Evolution of Precambrian life in the Brazilian geological record
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DOI：
10.1017/s1473550412000183
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发表时间：
2012-06
影响因子：
1.7
通讯作者：
T. Fairchild;E. A. Sanchez;M. L. Pacheco;Juliana de Moraes Leme
中科院分区：
文献类型：
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作者：
T. Fairchild;E. A. Sanchez;M. L. Pacheco;Juliana de Moraes Leme
摘要前寒武纪岩石占巴西地表面积的近四分之一，范围从古太古代（约2000年）到2000年。3.6 Ga）至埃迪卡拉纪晚期（0.542Ga）。除了有争议的磷酸盐化“胚胎样”微体化石，如来自中国埃迪卡拉纪陡山沱组下部的微体化石和复杂的岭型化石，巴西的研究已经揭示了其他地方描述的前寒武纪生命形式的所有主要类别-微生物岩，生物标志物，硅化微体化石，孢粉形，花瓶状微体化石，大型藻类，后生动物，vendobions和遗迹化石-但这一记录的古生物学意义很少被探索。这些化石至少出现了四次，为进一步了解前寒武纪生物圈演化的以下方面提供了希望：（i）米纳斯吉拉斯QuadrilánesFerrífero的米纳斯超群2.1-2.4 Ga老碳酸盐中微生物岩的关系（最古老的巴西化石）与早期含氧大气的发展和准同期的全球构造和气候事件有关;（ii）巴西中西部中元古代至埃迪卡拉纪有机壁微体化石的演化和生物地层学意义;（iii）Urucum组中瓶状异养原生生物微体化石的多样性和古生态学意义（Jacadigo群）和可能的Bocaina组（Corumbá Group），of南马托格罗索;以及（iv）以Corumbella丰富的有机甲壳和指示化石Cloudina的钙质壳为代表，深入了解埃迪卡拉纪最晚后生动物的骨骼发生和古生态学记录，位于南马托格罗索的Corumbá集团。因此，对巴西前寒武纪化石记录的分析具有很大的潜力，可以增加地球上这一关键时期的古生物学知识，并就其他行星上生物圈的可能起源和进化途径提出更有力的假设。
Abstract Precambrian rocks comprise nearly one-quarter of the surface of Brazil and range from Paleoarchean (ca. 3.6 Ga) to the latest Ediacaran (0.542 Ga) in age. Except for controversial phosphatized ‘embryo-like’ microfossils like those from the lower Ediacaran Doushantuo Formation, China and complex rangeomorphs, Brazilian research has revealed all major categories of Precambrian life forms described elsewhere – microbialites, biomarkers, silicified microfossils, palynomorphs, vase-shaped microfossils, macroalgae, metazoans, vendobionts and ichnofossils – but the paleobiological significance of this record has been little explored. At least four occurrences of these fossils offer promise for increased understanding of the following aspects of Precambrian biospheric evolution: (i) the relationship of microbialites in 2.1–2.4 Ga old carbonates of the Minas Supergroup in the Quadrilátero Ferrífero, Minas Gerais (the oldest Brazilian fossils) to the development of the early oxygenic atmosphere and penecontemporaneous global tectonic and climatic events; (ii) the evolutionary and biostratigraphic significance of Mesoproterozoic to Ediacaran organic-walled microfossils in central–western Brazil; (iii) diversity and paleoecological significance of vase-shaped heterotrophic protistan microfossils in the Urucum Formation (Jacadigo Group) and possibly the Bocaina Formation (Corumbá Group), of Mato Grosso do Sul; and (iv) insights into the record of skeletogenesis and paleoecology of latest Ediacaran metazoans as represented by the abundant organic carapaces of Corumbella and calcareous shells of the index fossil Cloudina, of the Corumbá Group, Mato Grosso do Sul. Analysis of the Brazilian Precambrian fossil record thus holds great potential for augmenting paleobiological knowledge of this crucial period on Earth and for developing more robust hypotheses regarding possible origins and evolutionary pathways of biospheres on other planets.