Cretaceous–Paleogene plant extinction and recovery in Patagonia
Cretaceous–Paleogene plant extinction and recovery in Patagonia
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DOI：
10.1017/pab.2020.45
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发表时间：
2020-11
期刊：
影响因子：
2.7
通讯作者：
E. Stiles;P. Wilf;A. Iglesias;M. Gandolfo;N. Cúneo
中科院分区：
文献类型：
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作者：
E. Stiles;P. Wilf;A. Iglesias;M. Gandolfo;N. Cúneo
摘要。白垩纪-古近纪（K/Pg）灭绝对某些生物类群来说似乎具有地理异质性。南半球的K/Pg孢粉学记录表明，与北半球相比，南半球的大植物区系灭绝率较低，恢复速度较快，但在这一区间内没有可比较的、约束良好的南半球大植物区系。本文首次在南半球研究了大型植物的更替模式，使用了来自阿根廷巴塔哥尼亚最晚白垩纪（马astrichtian）和最早古新世（Danian）的3500多片双叶植物叶片。据估计，在整个K/Pg地区，大型植物灭绝最多约90%，稀有物种丰富度下降约45%，这与物种水平的大规模灭绝和先前观察到的寄主特化叶矿的灭绝一致。然而，先前的孢粉学和分类学研究表明，在相同的剖面中，高等分类群的更替率较低，而一般花的组成则保持不变。物种灭绝程度高，物种丰富度下降，大年系大型植物区系在时间和相上的均匀性与北美洲相似，但也存在一些显著差异。与达科他地区威利斯顿盆地（WB）相似的绝对古纬度（约50°S或50°N）的跨界大型植物区系相比，马斯特里赫特和达尼安巴塔哥尼亚的物种丰富度都更高，将南美物种多样性提升的历史延伸到了马斯特里赫特。尽管物种更替率很高，但我们的分析还揭示了叶片形态空间的连续性和扩展，包括与大年系不同的裂片和齿状物种的增加。因此，巴塔哥尼亚和WB K/Pg大型植物区系都支持一个重要的灭绝事件，但它们也可能反映了地理上的异质性多样性、灭绝和恢复模式，值得未来的研究。
Abstract. The Cretaceous–Paleogene (K/Pg) extinction appears to have been geographically heterogeneous for some organismal groups. Southern Hemisphere K/Pg palynological records have shown lower extinction and faster recovery than in the Northern Hemisphere, but no comparable, well-constrained Southern Hemisphere macrofloras spanning this interval had been available. Here, macrofloral turnover patterns are addressed for the first time in the Southern Hemisphere, using more than 3500 dicot leaves from the latest Cretaceous (Maastrichtian) and the earliest Paleocene (Danian) of Argentine Patagonia. A maximum ca. 90% macrofloral extinction and ca. 45% drop in rarefied species richness is estimated across the K/Pg, consistent with substantial species-level extinction and previously observed extirpation of host-specialized leaf mines. However, prior palynological and taxonomic studies indicate low turnover of higher taxa and persistence of general floral composition in the same sections. High species extinction, decreased species richness, and homogeneous Danian macrofloras across time and facies resemble patterns often observed in North America, but there are several notable differences. When compared with boundary-spanning macrofloras at similar absolute paleolatitudes (ca. 50°S or 50°N) from the Williston Basin (WB) in the Dakotas, both Maastrichtian and Danian Patagonian species richnesses are higher, extending a history of elevated South American diversity into the Maastrichtian. Despite high species turnover, our analyses also reveal continuity and expansion of leaf morphospace, including an increase in lobed and toothed species unlike the Danian WB. Thus, both Patagonian and WB K/Pg macrofloras support a significant extinction event, but they may also reflect geographically heterogeneous diversity, extinction, and recovery patterns warranting future study.