Chemometric study of functional groups in different layers of Trigonocarpus grandis ovules (Pennsylvanian seed fern, Canada)

► First systematic FTIR chemical study of Carboniferous coalified ovules. ► Coalified ovules of Trigonocarpus grandis show preservation variability. ► Modern solid and liquid state FTIR methods provide semi-quantitative phytochemistry. ► A multivariate model (PCA) emphasizes the differentiation of sample forms.