導讀Bioon.net ：本期Nature封面所示為用顯微斷層攝影成像方式所顯示出的一個大化石（macrofossil）標本的結(jié)構(gòu)。研究發(fā)現(xiàn)該多細胞生物起源于21億年前,。
一支由法國等多國科學家組成的研究小組在最新一期英國《自然》雜志上報告說,，他們對化石的最新研究發(fā)現(xiàn)，多細胞生物起源于21億年前,，而不是此前人們認為的6億年前,。
據(jù)研究人員介紹，地球上最早的生命跡象出現(xiàn)于35億年前,，主要以原核生物形式存在,。在距今約6億年前的寒武紀，各種生物以爆炸性的速度涌現(xiàn),。不過生命的多樣化過程實際上發(fā)生于距今35億年到6億年前的元古代,，在此期間誕生了真核生物,，它們與原核生物的最大不同就是擁有了細胞核,。然而，此前科學界發(fā)現(xiàn)的中元古代（距今16億年至10億年前）之前的多細胞生物證據(jù)很少,。
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來自法國等國的科學家于2008年在加蓬的弗朗斯維爾意外發(fā)現(xiàn)了大批保存完好的生物化石,。根據(jù)對其周圍沉積物進行的測算，這些化石已有21億年的歷史,。這些罕見的古老生物化石長度在10厘米到12厘米之間,，堪稱“大化石”?？茖W家分析認為,，它們既不可能是原核生物，也不可能是單細胞真核生物,。
在進一步的分析中,，研究人員利用離子探測器對化石中硫同位素的成分進行了測定，并借助特殊設備繪制了標本的3D圖像,。結(jié)果顯示,，該生物化石正是多種組織的結(jié)合體，它也是迄今為止發(fā)現(xiàn)的最古老的多細胞真核生物,。(生物谷Bioon.net)
生物谷推薦原文出處：
Nature doi:10.1038/nature09166
Large colonial organisms with coordinated growth in oxygenated environments 2.1 Gyr ago
Abderrazak El Albani,Stefan Bengtson,Donald E. Canfield,Andrey Bekker,Roberto Macchiarelli,Arnaud Mazurier,Emma U. Hammarlund,Philippe Boulvais,Jean-Jacques Dupuy,Claude Fontaine,Franz T. Fürsich,Fran?ois Gauthier-Lafaye,Philippe Janvier,Emmanuelle Javaux,Frantz Ossa Ossa,Anne-Catherine Pierson-Wickmann,Armelle Riboulleau,Paul Sardini,Daniel Vachard,Martin Whitehouse& Alain Meunier
The evidence for macroscopic life during the Palaeoproterozoic era (2.5–1.6?Gyr ago) is controversial1, 2, 3, 4, 5. Except for the nearly 2-Gyr–old coil-shaped fossil Grypania spiralis6, 7, which may have been eukaryotic, evidence for morphological and taxonomic biodiversification of macroorganisms only occurs towards the beginning of the Mesoproterozoic era (1.6–1.0?Gyr)8. Here we report the discovery of centimetre-sized structures from the 2.1-Gyr-old black shales of the Palaeoproterozoic Francevillian B Formation in Gabon, which we interpret as highly organized and spatially discrete populations of colonial organisms. The structures are up to 12?cm in size and have characteristic shapes, with a simple but distinct ground pattern of flexible sheets and, usually, a permeating radial fabric. Geochemical analyses suggest that the sediments were deposited under an oxygenated water column. Carbon and sulphur isotopic data indicate that the structures were distinct biogenic objects, fossilized by pyritization early in the formation of the rock. The growth patterns deduced from the fossil morphologies suggest that the organisms showed cell-to-cell signalling and coordinated responses, as is commonly associated with multicellular organization9. The Gabon fossils, occurring after the 2.45–2.32-Gyr increase in atmospheric oxygen concentration10, may be seen as ancient representatives of multicellular life, which expanded so rapidly 1.5?Gyr later, in the Cambrian explosion.
