Oleanane is a triterpane that is commonly found in Cretaceous through Cenozoic marine and deltaic rocks and related oils. The Beta-Amyrin group forms the basis of many angiosperm triterpenoids and triterpenoid saponins. These compounds are widely distributed in angiosperms and appear common in moderately advanced flowering plant lineages where they are often used in defense. This group of compounds has not been reported from any other living seed plant group. Based on the correlation between increases in relative oleanane concentration in Cretaceous/Tertiary sediments and angiosperm diversification curves, oleanane is thought to be a molecular marker for terrestrial angiosperms. Our previous work has shown that oleanane is rarely found and is at lower relative concentration in Carboniferous to Jurassic samples. We have begun a preliminary study of lacustrine, fluvial and nearshore sediments with high terrestrial input of fossil plant remains, and of selected compressed and permineralized plant fossils of Devonian to Cretaceous. Oleanane does not appear to be present in the Upper Devonian progymnosperms, in the Carboniferous medullosans, cordaites and associated sediments, nor in Cretaceous conifers. However, oleanane does occur in Upper Permian gigantopterids and Lower Cretaceous bennettitaleans as well as in angiosperms. Previous phylogenetic analyses by several authors suggest that Bennettitales is a member of the anthophytes and thus oleanane may be a marker for this clade. The presence of oleanane in gigantopterids suggests that this group may be more closely related to anthophytes than previously realized. This is in according with a preliminary phylogenetic analysis. Whether all anthophytes are characterized by oleananes and/or related compounds needs to be further examined with additional investigation of the biomarkers in gnetophytes and Pentoxylon, and other related plant groups.

Key words: angiosperms, anthophytes, gigantopterids, Oleanane, phylogeny.