Quaternary Coleoptera Studies in North America: Past and Present

Abstract

Every coleopterist is well aware that the fossil record of his charge is poor in comparison with that of other invertebrate specialists, consisting principally of beautiful but rare specimens preserved in amber, and flattened, difficult to study, carbonaceous impressions in Permian and younger shales. Trained to accept that the selective nature of fossilization has not favored the preservation of insects, many entomologists are unaware that insect fossils are abundant in the unconsolidated sediments of Quaternary age. Considering that their existence has been known for over a hundred years, they have received relatively little attention. This is not altogether surprising as, until recently, little significance could be attached to their study. With the discovery that the fossil assemblages are sensitive indicators of terrestial environments, particularly climatic parameters, this changed, and studies are presently being conducted throughout North America. The Quaternary Period is an old stratigraphical term that has been revived in recent years to include the Pleistocene and Holocene Epochs. It covers approximately the last three million years, a time characterized by repeated world-wide climatic changes during which significant areas of the terrestial environment have been modified by glaciers, which in turn were responding to perturbations of northern and southern hemisphere ice caps. What effects the climatic shifts and the reduction of habitable land area had on insect populations is an old question for which there are numerous speculative answers.