Data from: Identifying the most surprising victims of mass extinction events: an example using late Ordovician brachiopods

Mass extinction events are recognized by increases in extinction rate and magnitude and, often, by changes in the selectivity of extinction. When considering the selective fingerprint of a particular event, not all taxon extinctions are equally informative: some would be expected even under a “background” selectivity regime, whereas others would not and thus require special explanation. When evaluating possible drivers for the extinction event, the latter group is of particular interest. Here we introduce a simple method for identifying these most surprising victims of extinction events by training models on background extinction intervals and using these models to make per-taxon assessments of “expected” risk during the extinction interval. As an example, we examine brachiopod genus extinctions during the Late Ordovician Mass Extinction and show that extinction of genera in the deep-water “Foliomena fauna” was particularly unexpected given preceding Late Ordovician extinction patterns.

大灭绝事件（mass extinction events）的识别依据为灭绝速率与灭绝规模的提升，且通常伴随灭绝选择性的改变。在探讨某一特定灭绝事件的选择性特征时，并非所有分类群的灭绝都具备同等的信息价值：部分类群的灭绝即便在“背景”灭绝选择性机制下也可被预期，而另一部分类群的灭绝则无法通过背景模式解释，因此需要专门的成因阐释。在评估该灭绝事件的潜在驱动因素时，后一类无法用背景模式解释的灭绝类群尤为值得关注。本文提出了一种简便方法：通过在背景灭绝间隔期训练统计模型，并利用该模型对灭绝间隔期内各分类群的“预期”风险进行逐项评估，以此识别灭绝事件中最具意外性的受害类群。作为示例，我们分析了奥陶纪晚期大灭绝（Late Ordovician Mass Extinction）期间的腕足动物属级灭绝事件，结果显示：结合奥陶纪晚期此前的灭绝模式来看，深海“Foliomena动物群（Foliomena fauna）”内各属的灭绝现象尤为出人意料。