Ecological impact of the end-Cretaceous extinction on lamniform sharks.
Ecological impact of the end-Cretaceous extinction on lamniform sharks.
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DOI：
10.1371/journal.pone.0178294
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发表时间：
2017
期刊：
影响因子：
3.7
通讯作者：
Twitchett RJ
中科院分区：
文献类型：
--
作者：
Belben RA;Underwood CJ;Johanson Z;Twitchett RJ
Lamniform sharks是顶级的海洋捕食者，在全球范围内正经历着局部和区域性的急剧减少，其对海洋生态系统的影响难以预测。在它们漫长的历史中，板形鲨面临着大范围的灭绝，了解这些“自然实验”可能有助于限制预测，将当前的危机置于进化的背景下。通过对鲨鱼牙齿化石进行新的形态计量学分析，我们发现，白垩纪末期许多鲨鱼的灭绝造成了重大的生态后果。灭绝后的生态系统支持较低的板形生物多样性和差异，并以明显较小的鲨鱼为主，它们的牙齿更细、更光滑、更不强壮。牙齿形状与生态、摄食和猎物类型密切相关，通过整合现存鲨鱼的数据，我们发现白垩纪晚期的鲨鱼与现代板形鲨鱼占据相似的生态位，这意味着相似的生态系统结构和功能。相比之下，灭绝后退化群落的物种所占据的生态位与幼年沙虎（Carcharias taurus）最相似。我们的数据表明，由于饮食差异，定量牙齿形态计量学可以区分板状鲨鱼，为过去灭绝事件的生态后果提供了重要的见解。
Lamniform sharks are apex marine predators undergoing dramatic local and regional decline worldwide, with consequences for marine ecosystems that are difficult to predict. Through their long history, lamniform sharks have faced widespread extinction, and understanding those ‘natural experiments’ may help constrain predictions, placing the current crisis in evolutionary context. Here we show, using novel morphometric analyses of fossil shark teeth, that the end-Cretaceous extinction of many sharks had major ecological consequences. Post-extinction ecosystems supported lower diversity and disparity of lamniforms, and were dominated by significantly smaller sharks with slimmer, smoother and less robust teeth. Tooth shape is intimately associated with ecology, feeding and prey type, and by integrating data from extant sharks we show that latest Cretaceous sharks occupied similar niches to modern lamniforms, implying similar ecosystem structure and function. By comparison, species in the depauperate post-extinction community occupied niches most similar to those of juvenile sand tigers (Carcharias taurus). Our data show that quantitative tooth morphometrics can distinguish lamniform sharks due to dietary differences, providing critical insights into ecological consequences of past extinction episodes.