Biotic replacement and mass extinction of the Ediacara biota
Biotic replacement and mass extinction of the Ediacara biota
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DOI：
10.1098/rspb.2015.1003
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发表时间：
2015-09-07
影响因子：
4.7
通讯作者：
Laflamme, Marc
中科院分区：
文献类型：
--
作者：
Darroch, Simon A. F.;Sperling, Erik A.;Laflamme, Marc
最新的埃迪卡拉生物群新元古代灭绝被各种各样的原因归结为全球地球化学循环扰动的灾难性移除，寒武纪生态系统工程师的“生物替代”，以及地形学人工制品。我们利用从纳米比亚南部最年轻的aliacaran地层收集的古生态和地球化学数据，对“生物替代”假说进行了第一次关键测试。我们发现，即使在考虑了各种潜在的采样和分类偏差之后，保存在Swartpunt农场的埃迪卡拉动物群的属丰富度也明显低于更古老的动物群。地球化学和沉积学分析证实了含氧和非限制性的含化石沉积物古环境，因此表明氧胁迫和/或高盐度不太可能是导致Swartpunt保存的群落多样性低的原因。这些综合分析表明，埃迪卡拉纪晚期的特征是群落衰竭，并为埃克利卡拉动物群终结的生物替代模型提供了第一个定量支持。尽管还需要更多的遗址（特别是那些记录不同古环境的遗址），但这项研究提供了第一个定量的古生态学证据，表明进化创新、生态系统工程和生物相互作用可能最终导致了复杂生命的第一次大灭绝。
The latest Neoproterozoic extinction of the Ediacara biota has been variously attributed to catastrophic removal by perturbations to global geochemical cycles, 'biotic replacement' by Cambrian-type ecosystem engineers, and a taphonomic artefact. We perform the first critical test of the 'biotic replacement' hypothesis using combined palaeoecological and geochemical data collected from the youngest aliacaran strata in southern Namibia. We find that, even after accounting for a variety of potential sampling and taphonomic biases, the Ediacaran assemblage preserved at Farm Swartpunt has significantly lower genus richness than older assemblages. Geochemical and sedimentological analyses confirm an oxygenated and non-restricted palaeoenvironment for fossil-bearing sediments, thus suggesting that oxygen stress and/or hypersalinity are unlikely to be responsible for the low diversity of communities preserved at Swartpunt. These combined analyses suggest depauperate communities characterized the latest Ediacaran and provide the first quantitative support for the biotic replacement model for the end of the Ecliacara biota. Although more sites (especially those recording different palaeoenvironments) are undoubtedly needed, this study provides the first quantitative palaeoecological evidence to suggest that evolutionary innovation, ecosystem engineering and biological interactions may have ultimately caused the first mass extinction of complex life.