EXCEPTIONAL PRESERVATION OF INSECTS IN LACUSTRINE ENVIRONMENTS

Insects are diverse and abundant components of most terrestrial ecosystems today and are well represented in the fossil record with first occurrences in the Early Devonian. Fossil deposits that include exceptionally preserved insect assemblages are found in several different types of Lagerstatten, with their preservation in amber and in lake sediments being of greatest importance. Researchers have used a variety of approaches to study the taphonomy of insects preserved in lacustrine environments and have identified several important variables that contribute to the preservation potential of insects. A combination of insect ecology, morphology, and the depositional setting in which an insect specimen rests influence the preservation potential of insects and ultimately affect the spatial, temporal, and compositional resolution of fossil assemblages. In general, lacustrine insect assemblages experience very little spatial and temporal averaging. Compositional fidelity of assemblages tends to be low, with an overabundance of allochthonous taxa from smaller size classes. In addition, the composition of fossil insect assemblages will be biased depending on the specimen's position within a lake, dependent on both water depth and distance from shore. Focus areas for future research are outlined, as are recommendations for improving field collecting methods and statistical approaches. Finally, the benefits of conducting synthetic studies using global databases and the importance of studying unexceptional deposits are discussed.