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Insects have been important components of terrestrial ecosystems for the last 400 Myr. They have been highly adaptable to a great variety of niches since their appearance, yet one of the most striking adaptations acquired are diverse cuticle patterning which primarily functions in intra- and interspecific communication. Patterning can consist of spots, eyespots and bands, these are formed by the uneven nature of the spatial distribution of pigments such as melanins and carotenoids. Fossil insects are found in diverse biotas with various characteristics of host sediment, the majority occur in restricted lacustrine Konservat-Lagerstätten with preservation of soft tissues. Fossil insects are usually disarticulated and frequently incomplete, particularly in those fossils older than 160 Myr. The incompleteness of the fossil record of insects is the result of three main biases: i) nature of tissues and pre-burial processes; ii) lithology and environment of deposition; iii) position of the body respective to the sediment at the time of burial. Fossil biomolecules present a valuable opportunity to have a peek at long extinct organisms and their ecological relationships. Most fossilized biomolecules endured great chemical changes that permitted them to be more stable over long periods of time, however, the original structure is often preserved enabling recognition after fossilisation. Whereas the chemical changes undergone by arthropod chitin through decay and preservation processes have been extensively investigated in insects and arthropods in general, there has been little attempt to characterise other possible molecular remains in insects. Can we identify pigment molecules in fossil insects? Left: Most commonly found types of pigment molecules in the cuticle of extant insects. a simplified melanin molecule; b pterin molecules; c ommochrome molecules; d flavonoid molecules; e carotenoid molecules. |