Abstract Ruflorinia orlandoi (Pteridospermophyta) fronds are chemically analyzed for the first time by semi-quantitative Fourier transform infrared (FTIR) spectroscopy. This analysis allows the chemical characterization of the mesophyll and cuticle revealing the functional groups preserved in different frond parts (pinnae and rachis). The specimens collected in the Springhill Formation at the Rio Correntoso locality (Lower Cretaceous, Santa Cruz province, Argentina) are compressions with very well-preserved cuticular features. The R. orlandoi remains (pinnae and rachis) are spectroscopically analyzed into two samples: compressions (Cp) and cuticles (Ct). Additionally, a third sample form from the host rock and named associated coal (V) is spectroscopically analyzed. Semi-quantitative data derived from Cp, Ct, and V spectra are evaluated by principal component analysis. The results indicate that Cp samples have a similar chemical composition whereas Ct samples show a greater variability. The latter could be related to intraspecific variability of foliar characters (e.g., trichomes and cuticular striations). Furthermore, Ct samples exhibit high contents of aromatic carbon groups suggesting a distinctive composition, likely including cutin/cutan biomacropolymers and/or phenolic compounds. Considering each specimen, the rachis shows a higher aromatic carbon content than pinnae as a consequence of the presence of more lignified tissues in the former. The V samples have the lowest relative intensity of aliphatic groups. On the other hand, the functional-group composition of R. orlandoi remains and V samples are compared with kerogen types and coal macerals showing a general chemical composition similar to type II kerogen. The latter is related to cuticles, spores, pollen grains, and resins.

中文翻译：

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蕨类植物 Ruflorinia orlandoi 和寄主岩的 FTIR 光谱特征（Springhill 组，下白垩纪，阿根廷）

摘要 Ruflorinia orlandoi (Pteridospermophyta) 的叶子首次通过半定量傅里叶变换红外 (FTIR) 光谱进行化学分析。该分析允许叶肉和角质层的化学特征揭示保留在不同叶状部分（羽片和羽轴）中的功能基团。在 Rio Correntoso 地区（阿根廷圣克鲁斯省下白垩纪）的 Springhill 组中收集的标本是具有保存完好的表皮特征的压缩物。R. orlandoi 遗骸（耳廓和羽轴）被光谱分析为两个样本：压缩 (Cp) 和角质层 (Ct)。此外，对来自母岩并命名为伴生煤 (V) 的第三种样品进行了光谱分析。半定量数据来源于 Cp、Ct、和 V 谱通过主成分分析进行评估。结果表明 Cp 样品具有相似的化学成分，而 Ct 样品显示出更大的变异性。后者可能与叶特征（例如毛状体和表皮条纹）的种内变异性有关。此外，Ct 样品显示出高含量的芳香碳基团，表明其组成独特，可能包括角质/皮肤生物大分子聚合物和/或酚类化合物。考虑到每个样本，由于在前者中存在更多木质化组织，因此轴显示出比耳廓更高的芳香碳含量。V 样品具有最低的脂肪族基团相对强度。另一方面，R 的官能团组成。orlandoi 遗迹和 V 样品与干酪根类型和煤质进行比较，显示出与 II 型干酪根相似的一般化学成分。后者与角质层、孢子、花粉粒和树脂有关。