Compositions of resistant macromolecules in fossil dry fruits of Liquidambar and Nyssa (Pliocene, central Japan)

We investigated the products released by hydrolysis of the resistant macromolecules of fossil dry fruits of angiosperms (Liquidambar and Nyssa) from the Pliocene fluvial sediments of the Tokai Group (central Japan), as well as extant dry fruits of Liquidambar, with respect to examining the chemotaxonomic potential and diagenetic alteration of these macromolecules. The main compounds released were n-alkanols, α,ω-alkanediols, alkanoic acids, ω-hydroxy acids and α,ω-alkanedioic acids. The carbon number distributions of the n-alkanols, α,ω-alkanediols and alkanoic acids released are similar for the fossil and extant dry fruits; the n-alkanols, presumably derived from suberin, are well preserved in the plant fossils. In contrast, the carbon number distributions of the ω-hydroxy acids and α,ω-alkanedioic acids are different, suggesting diagenetic alteration. Similarly, high abundances of low molecular weight n-alkanols from fossil Nyssa suggest diagenetic incorporation of bacterial lipids into the geomacromolecule.