PREMISE Fossil leaf traits can enable reconstruction of ancient environments and climates. Among these, leaf size has been particularly studied because it reflects several climatic forcings (e.g., precipitation and surface temperature) and, potentially, environment characteristics (e.g., nutrient availability, local topography, and openness of vegetation). However, imperfect preservation and fragmentation can corrupt its utilization. We provide improved methodology to estimate leaf size from fossil fragments. METHODS We apply three methods: (1) visually reconstructing leaf area based on taxon-specific gross morphology; (2) estimating intact leaf area from vein density based on a vein scaling relationship; and (3) a novel complementary method, determining intact leaf length based on the tapering of the midvein in the fragment. We test the three methods for fossils of extinct Eotrigonobalanus furcinervis (Fagaceae) from two lignite horizons of the middle and late Eocene of central Germany respectively (~45/46 and 35/36 Ma). RESULTS The three methods, including the new one, yield consistent leaf size reconstructions. The vein scaling method showed a shift to larger leaf size, from the middle to the late Eocene. CONCLUSIONS These methods constitute a toolbox with different solutions to reconstruct leaf size from fossil fragments depending on fossil preservation. Fossil leaf size reconstruction has great potential to improve physiognomy-based paleoenvironmental reconstructions and the interpretation of the fossil record.

中文翻译：

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从碎片重建叶面积：使用化石古近系物种测试三种方法

前提 叶化石特征可以重建古老的环境和气候。其中，对叶片大小进行了特别研究，因为它反映了几种气候强迫（例如，降水和地表温度）以及潜在的环境特征（例如，养分有效性、当地地形和植被的开放度）。然而，不完美的保存和碎片化会破坏它的利用。我们提供了改进的方法来估计化石碎片的叶子大小。方法 我们采用三种方法：（1）基于分类群特定的大体形态视觉重建叶面积；(2)根据叶脉比例关系从叶脉密度估计完整叶面积；(3) 一种新的互补方法，根据片段中脉的逐渐变细确定完整叶长。我们分别测试了来自德国中部始新世中期和晚期两个褐煤层（~45/46 和 35/36 Ma）的已灭绝 Eotrigonobalanus furcinervis（壳斗科）化石的三种方法。结果 这三种方法，包括新方法，产生一致的叶大小重建。静脉缩放方法显示了从始新世中期到晚期叶尺寸的转变。结论这些方法构成了一个工具箱，具有不同的解决方案，可根据化石保存情况从化石碎片重建叶片大小。化石叶片大小重建在改善基于地貌的古环境重建和化石记录的解释方面具有巨大潜力。