Phyllocladane is a tricyclic diterpane which is generally found in gymnosperm resins.

Diterpanes, such as Phyllocladane are found in source rocks as early as the middle and late Devonian periods, which indicates any rock containing them must be no more than approximately 360 Ma.

Phyllocladane is commonly found in lignite, and like other resinites derived from gymnosperms, is naturally enriched in 13C.

This enrichment is a result of the enzymatic pathways used to synthesize the compound.

Presence of phyllocladane and its relative abundance to other tricyclic diterpanes can be used to differentiate between various oil fields.