FAUNAL ASSEMBLAGES AND DISTRIBUTIONAL SHIFTS OF COLEOPTERA DURING THE LATE PLEISTOCENE IN CANADA AND THE NORTHERN UNITED STATES

Abstract

AbstractA faunal list of 362 sub-fossil Coleoptera obtained from 33 published and 24 unpublished sites of Pleistocene age in Canada and the neighbouring United States is given. A table indicates the distribution of families, with the number of species encountered, through discrete intervals of Pleistocene time. Seven species representing members of the Carabidae, Hydrophilidae, Staphylinidae, and Scolytidae have been used to illustrate distribution changes through the last interglacial/glacial/present interglacial cycle. The maximum distance so far recorded is a shift of over 9000 km for Anotylus gibbulus (Epp.), a staphylinid, found fossil in Toronto during the last interglacial, and today recorded only from Eurasia and Asia. A number of other species whose modern ranges are confined to northwestern North America have been found fossil in the Great Lakes – St. Lawrence region, over 4000 km distant. A similar shift is noted in species which today are found only in the eastern Canadian Arctic. Aspects of ice build up, marginal conditions outside the Laurentide Ice Sheet limits, Pleistocene climates, paleoecology, and sub-fossil insect localities are used to formulate hypotheses about three refugia around the perimeter of the Late Wisconsinan ice.