Science2014-07-01 3:26 PM

动物构建礁石的一个更古老的起源 Ediacaran metazoan reefs from the Nama Group, Namibia

论文摘要 

在纳米比亚发现了一个大约有5.48亿年之久的珊瑚礁,它们是由已知的世界上最早的骨骼动物构成的,这提示,这些水生生物在寒武纪大爆发之前就已经在构建珊瑚礁了。在此之前,记录在案的由这种后生动物组成的最老的珊瑚礁可追溯到大约5.3亿年前,而研究人员一直认为某些防御性策略,如形成骨骼或构建珊瑚礁的出现主要是为了因应大约5.4亿万年前大多数主要动物门相对快速出现的情况。但Amelia Penny及其同事在纳米比亚发现了这一更古老的珊瑚礁;他们说,它是由附着并粘结在一起的克劳德物种组成的。他们说,在某后生动物中的这种行为代表了一个重要的生态创新,个体生物通过这种共同协作能更好地进食并维持较好的被保护状态。研究人员的这些发现意味着后生动物在寒武纪大爆发之前几百万年就已经在构建珊瑚礁了——而且导致动物产生如骨骼及珊瑚礁等坚硬部分的进化压力在物种大爆发事件之前的数百万年时就已经存在了。

Abstract 

Reef-building in metazoans represents an important ecological innovation whereby individuals collectively enhance feeding efficiency and gain protection from competitors and predation. The appearance of metazoan reefs in the fossil record therefore indicates an adaptive response to complex ecological pressures. In the Nama Group, Namibia, we found evidence of reef-building by the earliest known skeletal metazoan, the globally distributed Cloudina, ~548 million years ago. These Cloudina reefs formed open frameworks without a microbial component but with mutual attachment and cementation between individuals. Orientated growth implies a passive suspension-feeding habit into nutrient-rich currents. The characteristics of Cloudina support the view that metazoan reef-building was promoted by the rise of substrate competitors and predators.

Editor's Summary

Building coral reefs in ancient times

540 million years ago, in the dawn before the Cambrian explosion, evolution was setting the stage for the global rise of animals. Before they took over the seas, the earliest animals developed strategies to defend themselves against predators. These strategies, which remain common today, include forming skeletons and building reefs. Penny et al. discovered a massive fossil reef deposit in Namibia made up of tiny coneshaped early animals known as Cloudina. The reef, which is 20 million years older than other ancient reefs, was probably formed as the Cloudina adapted to benefit from reefs, which protect the animals and allow them to feed more efficiently.

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