The chemistry of American and African amber, copal, and resin from the genus Hymenaea

The comparison of the chemical composition of fossilized amber, copal, and resin is important for determining the botanic origin and original chemical composition of fossilized amber and copal, and for understanding the ecologic role of resin. Here we use solid phase microextraction-gas chromatography-mass spectrometry (SPME-GC-MS) to investigate the volatile and semi-volatile composition of amber, copal and resin from Africa and the Americas, produced by trees from the genus Hymenaea. We found there are four subgroups of Hymenaea resin, copal, and amber, based upon age and chemical similarity: African amber, American amber, African resin/copal (which also includes Colombian copal), and American resin/copal. This analysis allows us to narrow down the potential botanic origin of amber and copal samples, and also indicates that within this genus, resin similarity does not correspond closely with phylogenetic relationships. Therefore, resin chemistry may have been controlled by ecologic pressures, such as defence against herbivores, wood borers, humidity, and diseases and the original chemical composition of amber and copal could potentially be used to understand the role of resin in plant-insect interactions through time.