s**l 发帖数: 11983 | 1 http://www.nature.com/nature/journal/v470/n7334/full/nature0981
An early Ediacaran assemblage of macroscopic and morphologically
differentiated eukaryotes
地球上最古老的「高等生命」到底是什么样子?人类已知的高等生命从什么时期开始演
化?英国的《自然》(Nature)杂誌在17日公佈了这一重大发现。
地球上的生命从无到有、从简单到复杂,其中的进化过程相当漫长。古生物学家认
为,在现今生物圈中,包括我们人类在内的所有肉眼可见的生命,几乎都是多细胞宏体
生物,也就是常说的「高等生命」,而多细胞宏体生物的出现是地球生命进化史上极为
重要的事件。
但是学术界一直认为地球没有早于5.8亿年前的「高等生命」,不过中国科学家在
安徽休甯县蓝田镇找到的「蓝田植物群」把高等生命起源向前推进了近4000万年。
「蓝田植物群」就在知名的景点黄山附近,出现在6亿多年前,展现了早期动物大规模
出现前夕的生命景观,是地球早期生命从简单向复杂进化过程中的重要环节。
「蓝田植物群」的出土为高等生命的早期演化提供了最古老的化石证据,也是地球
上迄今最早的宏体生物。不过科学家尚不确定为什么这些最古老的高等生命生存于安静
的水体中,演变过程也还是个未解之迷,有待更进一步的研究。
Abstract: The deep-water Avalon biota (about 579 to 565 million years old)
is often regarded as the earliest-known fossil assemblage with macroscopic
and morphologically complex life forms1. It has been proposed that the rise
of the Avalon biota was triggered by the oxygenation of mid-Ediacaran deep
oceans2. Here we report a diverse assemblage of morphologically
differentiated benthic macrofossils that were preserved largely in situ as
carbonaceous compressions in black shales of the Ediacaran Lantian Formation
(southern Anhui Province, South China). The Lantian biota, probably older
than and taxonomically distinct from the Avalon biota, suggests that
morphological diversification of macroscopic eukaryotes may have occurred in
the early Ediacaran Period, perhaps shortly after the Marinoan glaciation,
and that the redox history of Ediacaran oceans was more complex than
previously thought. |
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