The excellent preservation of plant macrofossils of the Miocene Clarkia flora, Emerald Creek, Idaho, USA, allowed the analysis of the extractable chemical compounds of five fossil conifer species. Foliar branches and cones of Cunninghamia chaneyi, Glyptostrobus oregonensis and Taxodium dubium (Taxodiaceae) and foliar branches of Metasequoia occidentalis (Taxodiaceae) and Calocedrus sp. (Cupressaceae) have been extracted with organic solvents, and the extracts have been analyzed as is and derivatized using gas chromatography-mass spectrometry. Generally, the extracts from foliar branches and cones of the same species showed similar extract patterns while the extracts from different species yielded different extract compositions. Several sesqui- and diterpenoids that probably originate from the resins have been identified. Most of the terpenoids have been degraded during diagenesis, but some compounds have been preserved unaltered. An aliphatic alcohol, n-nonacosan-10-ol, that occurs in the waxes of extant conifers was present in the foliage of all investigated fossil conifers. Furthermore, all conifer species contained the diterpenoids ferruginol and 6,7-dihydroferruginol which are known from extant species of Cupressaceae, Taxodiaceae and Podocarpaceae. The fossil conifer species showed characteristic diterpenoid patterns which in part match the compounds that have been found in related extant species. In Taxodium dubium some terpenoids (sugiol, ferruginol methylether, isochamaecydine) have been identified which also occur in extant T. distichum. Glyptostrobus oregonensis contains terpenoids similar to Taxodium dubium, but lacks ferruginol methylether. Cunninghamia chaneyi is characterized by two diterpenoids (hinokiol, hinokione) that have also been identified in the extracts of extant C. lanceolata. Specific terpenoids have not been observed in the foliar branches of Metasequoia occidentalis. Extracts of Calocedrus sp. (Cupressaceae) contain totarol which is known from numerous extant species of Cupressaceae and Podocarpaceae, but has been described only from one species of the Taxodiaceae (Cryptomeria).

Key words: biogeochemistry, biomarker, Clarkia, conifers, Miocene, terpenoids