Conifers are a major source of sedimentary leaf wax n-alkanes when dominant in the landscape: Case studies from the Paleogene

•Conifers add leaf wax n-alkanes to sediments when they dominate the landscape.•Some conifer taxa provide subtly different n-alkane chain length patterns.•Relative abundance of n-alkanes/terpenoids qualitatively relate to paleovegetation.•Plant terpenoid δ13C values can be used to detect the source of n-alkanes.•n-Alkanes from conifers can be 2–6‰ 13C-enriched than those from angiosperms.