• Fossil grass silica short cell phytoliths (GSSCP) have been used to reconstruct the biogeography of Poaceae, untangle crop domestication history and detect past vegetation shifts. These inferences depend on accurately identifying the clade to which the fossils belong. Patterns of GSSCP shape and size variation across the family have not been established and current classification methods are subjective or based on a 2D view that ignores important 3D shape variation.
• Focusing on Poaceae subfamilies Anomochlooideae, Pharoideae, Pueliodieae, Bambusoideae and Oryzoideae, we observed in situ GSSCP to establish their orientation and imaged isolated GSSCP using confocal microscopy to produce 3D models. 3D geometric morphometrics was used to analyze GSSCP shape and size. Classification models were applied to GSSCP from Eocene sediments from Nebraska, USA, and Anatolia, Turkey.
• There were significant shape differences between nearly all recognized GSSCP morphotypes and between clades with shared morphotypes. Most of the Eocene GSSCP were classified as woody bamboos with some distinctive Nebraska GSSCP classified as herbaceous bamboos.
• 3D morphometrics hold great promise for GSSCP classification. It accounts for the complete GSSCP shape, automates size measurements and accommodates the complete range of morphotypes within a single analytical framework.

中文翻译：

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草二氧化硅短细胞植硅石的3D形状分析：化石分类和形状演变分析的新方法。

• 化石草硅短细胞植硅体（GSSCP）已用于重建禾本科的生物地理学，弄清作物的驯化历史并检测过去的植被变化。这些推断取决于准确识别化石所属的进化枝。尚未确定整个家庭中GSSCP形状和大小变化的模式，当前的分类方法是主观的或基于忽略重要3D形状变化的2D视图。
• 着眼于禾本科（Poaceae）的亚科（Anomochlooideae），伞形科（Pharoideae），伞形科（Pueliodieaeae），竹杆菌科（Bambusoideae）和稻科（Oryzoideae），我们观察到了原位GSSCP的方向，并使用共聚焦显微镜对孤立的GSSCP进行了成像，以产生3D模型。使用3D几何形态计量学来分析GSSCP的形状和大小。分类模型应用于来自美国内布拉斯加和土耳其安那托利亚的始新世沉积物的GSSCP。
• 在几乎所有公认的GSSCP形态之间以及具有共同形态的进化枝之间，形状存在显着差异。大部分始新世GSSCP被归类为木竹，而内布拉斯加州GSSCP则被归类为草本竹。
• 3D形态计量学对GSSCP分类具有广阔的前景。它说明了完整的GSSCP形状，可自动进行尺寸测量，并在单个分析框架内容纳完整的形态型范围。