Figure 3

(A) GC–MS total ion chromatograms of aromatic fractions of true fern sample TF-1 (Diplazites unita) (i) fossil, (ii) inner matrix, and (iii) outer matrix. (B) Triterpenoid region of aromatic fraction of TF-1 fossil. Peaks labelled using roman numerals according to structure numbers in Fig. S1. Compounds were identified by comparison of their mass spectra with those reported in the literature^{7,37,40,41,48} (Fig. S3B). Other unidentified peaks had mass spectra that suggested a relationship to a DAPH (XI, XII) structure, denoted in the figure by squares. Filled squares represent probable C₂₈ diaromatic compounds and the empty square represents a probable C₂₉ diaromatic compound (examples with relevant retention time shown in Fig. S3C).