Alternative origin of aliphatic polymer in kerogen

The origin of sedimentary organic matter (kerogen) has been attributed to r andom recombination reactions of biological components in sediments or to s elective preservation of decay-resistant macromolecules. Neither hypothesis explains the aliphatic composition of the cuticle of fossil arthropods. Th ermal maturation experiments on modern arthropods, involving confined pyrol ysis at 250-360 degrees C, degrade the chitin-protein complex of the cuticl e and transform free aliphatic components into a polymeric structure. The r esults of the application of electron microscopy and spectroscopic methods to modern, thermally matured, and fossil arthropod cuticles indicate that i n situ polymerization of free and ester-bound cuticular lipids can lead to kerogen formation. Thus, fossil arthropod fragments can contribute to sedim entary organic matter.