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Nat Com:比利时学者揭示气候变化是鱼龙灭绝的幕后黑手

摘要 : 2016年3月8日,国际学术权威刊物自然出版集团旗下子刊《Nature Communications》杂志上在线发表比利时列日大学Valentin Fischer的一篇研究论文。

 2016年3月8日,国际学术权威刊物自然出版集团旗下子刊《Nature Communications》杂志上在线发表比利时列日大学Valentin Fischer的一篇研究论文。

文章指出一种像海豚的标志性的海洋爬行动物——鱼龙的灭绝收到了气候不稳定和演化速度减缓的驱使。鱼龙大约在9000万年前的白垩纪晚期灭绝,比白垩纪末期的让恐龙消失掉让哺乳动物有机会主导食物链的大灭绝早了2800万年。

虽然有人提出过和其他海洋爬行动物的竞争增加,或者食物资源的减少是可能导致鱼龙提早灭绝的原因,最近的研究显示鱼龙在灭绝前几百万年依然拥有丰富的物种多样性,于是导致他们完全消失掉的原因尚不清楚。

Valentin Fischer和他的研究团队使用了基于系统发生学的方法来估计了鱼龙随着时间推移的多样性,并且和例如海洋化学和海平面高度等环境数据进行了比对。他们发现鱼龙在白垩纪早期一直是高度多样化的,而最后的鱼龙的演化速率越来越低。研究者的数据支持气候变化是海洋生态系统变化的主要驱动力的观点,不支持鱼龙是被其他海洋爬行动物和鱼类打败了的假说。

另外,这项研究发现了一个早期的灭迹时间(大约1亿年前)也降低了鱼龙的多样性。因此,研究者认为鱼龙的灭绝是个两部分的过程。

原文链接:

Extinction of fish-shaped marine reptiles associated with reduced evolutionary rates and global environmental volatility

原文摘要:

Despite their profound adaptations to the aquatic realm and their apparent success throughout the Triassic and the Jurassic, ichthyosaurs became extinct roughly 30 million years before the end-Cretaceous mass extinction. Current hypotheses for this early demise involve relatively minor biotic events, but are at odds with recent understanding of the ichthyosaur fossil record. Here, we show that ichthyosaurs maintained high but diminishing richness and disparity throughout the Early Cretaceous. The last ichthyosaurs are characterized by reduced rates of origination and phenotypic evolution and their elevated extinction rates correlate with increased environmental volatility. In addition, we find that ichthyosaurs suffered from a profound Early Cenomanian extinction that reduced their ecological diversity, likely contributing to their final extinction at the end of the Cenomanian. Our results support a growing body of evidence revealing that global environmental change resulted in a major, temporally staggered turnover event that profoundly reorganized marine ecosystems during the Cenomanian.

来源: Nature Communications 浏览次数:0

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