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首页> 外文期刊>Proceedings of the National Academy of Sciences of the United States of America >A scale of greatness and causal classification of mass extinctions: Implications for mechanisms
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A scale of greatness and causal classification of mass extinctions: Implications for mechanisms

机译：大规模灭绝的规模和因果分类：对机制的启示

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摘要

A quantitative scale for measuring greatness, G, of mass extinctions is proposed on the basis of rate of biodiversity diminution expressed as the product of the loss of biodiversity, called magnitude (M), and the inverse of time in which that loss occurs, designated as intensity (I). On this scale, the catastrophic Cretaceous-Tertiary (K-T) extinction appears as the greatest since the Ordovician and the only one with a probable extraterrestrial cause. The end-Permian extinction was less great but with a large magnitude (M) and smaller intensity (I); only some of its individual episodes involved some semblance of catastrophe. Other extinctions during the Phanerozoic, with the possible exception of the end-Silurian diversity plunge, were parts of a forced oscillatory phenomenon and seem caused by marine- and land-habitat destruction during continental assemblies that led to elimination of shelves and (after the Devonian) rain forests and enlargement of deserts. Glaciations and orogenies that shortened and thickened the continental crust only exacerbated these effects. During the Mesozoic and Cainozoic, the evolution of life was linearly progressive, interrupted catastrophically only at the K-T boundary. The end-Triassic extinction was more like the Paleozoic extinctions in nature and probably also in its cause. By contrast, the current extinction resembles none of the earlier ones and may end up being the greatest of all.
机译：根据生物多样性减少的速率（表示为生物多样性丧失的乘积，称为幅度（M）），以及该损失发生的时间的倒数，提出了一种用于度量灭绝的巨大度G的定量标度。作为强度（I）。在这种规模上，灾难性的白垩纪-第三纪（K-T）灭绝似乎是自奥陶纪以来最大的灭绝事件，并且是唯一可能是外星起因的物种。二叠纪末期的灭绝作用较小，但强度较大（M），强度较小（I）。它的某些个别事件只涉及到一些灾难。远古生代期间的其他物种灭绝，除了可能发生的西卢里亚末期生物多样性暴跌外，都是强迫振​​荡现象的一部分，似乎是由于大陆集会期间的海洋和陆地栖息地破坏所致，从而导致了陆架的消灭和（泥盆纪之后）。 ）雨林和沙漠的扩大。缩短和增厚大陆壳的冰川和造山运动只会加剧这些影响。在中生代和新生代，生命的发展是线性渐进的，仅在K-T边界发生灾难性的中断。三叠纪末期的灭绝更像是自然界的古生代灭绝，也可能是其成因。相比之下，目前的灭绝与早期灭绝没有相似之处，可能最终成为最大灭绝物种。

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