Biomarker compositions of Glyptostrobus and Metasequoia (Cupressaceae) fossils from the Eocene Buchanan Lake Formation, Axel Heiberg Island, Nunavut, Canada reflect diagenesis from terpenoids of their related extant species

The solvent extractable organic compounds of two fossil conifer species from the Eocene Buchanan Lake Formation, Axel Heiberg Island, Canada, were compared to the compound composition of related extant species to investigate the preservation and degradation (diagenesis) of terpenoid biomarkers in geological samples. Mono-, di- and triterpenoids, lignin components and aliphatic lipids were identified in the solvent extracts of the fossil and extant conifers. The biomarker composition of fossil Glyptostrobus shoots and seed cones is different from their pattern observed in fossil Metasequoia. The comparison of terpenoids found in fossil plant extracts with those present in their related extant species shows similar patterns of terpenoid biomarkers and confirms the systematic assignment of fossil species based on morphological and anatomic characteristics. The presence of unaltered natural product terpenoids and their only slightly altered diagenetic derivatives (biomarkers) reflect the excellent preservation of the Eocene fossils from the Buchanan Lake Formation.