Cooler winters as a possible cause of mass extinctions at the eocene/oligocene boundary
Cooler winters as a possible cause of mass extinctions at the eocene/oligocene boundary
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DOI：
10.1038/35038044
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发表时间：
2000-10-19
期刊：
影响因子：
64.8
通讯作者：
Lohmann, KC
中科院分区：
文献类型：
--
作者：
Ivany, LC;Patterson, WP;Lohmann, KC
始新世/渐新世的界线，大约在3370万年前，标志着新生代海洋无脊椎动物最大的灭绝之一（1）。例如，在美国海湾沿岸平原的软体动物物种的营业额在这个时候超过90%（2，3）。跨越这一边界的温度变化-从温暖的始新世气候到渐新世的凉爽条件-被认为是这次灭绝事件的原因，但气候重建并没有为这一假设提供支持。在这里，我们报告的稳定氧同位素测量文石鱼耳石耳石收集始新世/渐新世边界。根据平均耳石氧同位素值重建的古温度在这段时间内几乎没有变化，这与以前的研究一致（5，6）。然而，从耳石的增量微取样，我们可以解决温度的季节性变化，记录为耳石继续在鱼的生命中增加新的物质。这些季节性数据表明，在始新世/渐新世边界，冬天的温度降低了约4摄氏度。我们认为，温度的变化，而不是年平均温度的变化，有助于导致动物区系周转在这个过渡。
The Eocene/Oligocene boundary, at about 33.7 Myr ago, marks one of the largest extinctions of marine invertebrates in the Cenozoic period(1). For example, turnover of mollusc species in the US Gulf coastal plain was over 90% at this time(2,3). A temperature change across this boundary-from warm Eocene climates to cooler conditions in the Oligocene-has been suggested as a cause of this extinction event(4), but climate reconstructions have not provided support for this hypothesis. Here we report stable oxygen isotope measurements of aragonite in fish otoliths-ear stones-collected across the Eocene/Oligocene boundary. Palaeotemperatures reconstructed from mean otolith oxygen isotope values show little change through this interval, in agreement with previous studies(5,6). From incremental microsampling of otoliths, however, we can resolve the seasonal variation in temperature, recorded as the otoliths continue to accrete new material over the life of the fish. These seasonal data suggest that winters became about 4 degrees C colder across the Eocene/Oligocene boundary. We suggest that temperature variability, rather than change in mean annual temperature, helped to cause faunal turnover during this transition.