Chemical analysis of the leaves of modern Metasequoia and other gymnosperms revealed the presence of structural polyesters, guaiacyl lignin units and polysaccharides, but no long chain recalcitrant aliphatic constituent. Analysis of Tertiary fossil Metasequoia showed the presence of polysaccharides, lignin and a long chain aliphatic polymer. Tertiary fossil conifers similarly revealed the preservation of lignin and a long chain aliphatic polymer (up to C₃₃) with limited preservation of polysaccharides. Experimental maturation of modern pine needles generated a composition with a long chain aliphatic polymer and additional phenolic compounds similar to those seen in the fossils. Experimental maturation of the structural polyester cutin and a pure model C₁₆ and C₁₈ fatty acid mixture yielded fatty acids and an aliphatic polymer less than C₂₀ suggesting that polymers greater than C₂₀ may be incorporated into the fossil macromolecule from longer-chain plant waxes. Thermochemolysis of the fossil conifer revealed fatty acids from C₁₂ to C₃₀ that also occur in internal lipids and the initial structural polyester. This suggests that the formation of the aliphatic polymer in the fossil Metasequoia may have been the result of lipid incorporation, a process likely important in the long-term preservation of gymnosperms and other organic macrofossils.