Chapter 4 - Amber

Abstract

This chapter discusses amber, which is a fossilized resin ranging from several million to 300 million years of age. Amber is a gold mine for the entomologist because it contains a variety of insects preserved in pristine, three-dimensional condition. External features are so well preserved that taxonomists can make detailed comparisons with living taxa to follow evolutionary development of families, genera, and species. Aside from establishing direct evidence of an insect taxon at a particular time and place, the presence of specific insects provides indirect evidence of plants and vertebrates, establishes the time frame for symbiotic associations, and provides clues for reconstructing ancient landscapes. As a result of the excellent preservation of amber arthropods, the ancestry of specific genera and families can be traced back to tens of millions of years. Discovering extinct generic and family lineages is also possible, especially in Cretaceous amber. Further, amber insects can provide evidence of specific habitats. Because of the sudden death of captured organisms in amber, symbiotic associations may be preserved in a manner unlikely to occur with other types of preservation. Also, the fine details of preservation may reveal morphological features characteristic of symbiotic associations. Cases of paleosymbiosis in amber include inquilinism, commensalism, mutualism, and parasitism. Amber insects can provide evidence of past distributions as well as clues to climatic regimens that occurred at the original sites.