Chemical preservation of plants and insects in natural resins

The morphological preservation of fossils in amber is remarkable, but their chemical composition is largely unknown. The likelihood of DNA preservation in amber has been questioned but, surprisingly, the fate of more decayresistant macromolecules such as lignocellulose in plants or the chitinprotein complex in insect cuticle has not been investigated. Here we report the results of investigations using pyrolysisgas chromatography/mass spectrometry (pyGC/MS) of the tissues of insects and the plant Hymenaea from ancient and subfossil resins (220 ka) from Kenya, and from Dominican amber (2530 Ma). The volatile components of the resin have penetrated even the internal tissues, resulting in the exceptional threedimensional preservation of amber inclusions. Chitin is preserved in the bee and lignocellulose in the Hymenaea leaf from the Kenyan resins. There was no trace, however, of these macromolecules in tissues in Dominican amber. The presence of aliphatic polymer and sulphurcontaining moieties in these tissues indicates that they have undergone diagenetic alteration; in view of this, the preservation in Dominican amber of a macromolecule as labile as DNA would be extraordinary.