Pre-Vashon fossil Coleoptera of Fraser age from the Fraser Lowland, British Columbia

Abstract

Samples of organic silt from post-Coquitlam Quadra sand at Port Moody and Mary Hill, British Columbia (dated at 18 300 and 18 700 years BP, respectively) were examined for insect remains and yielded small assemblages of beetles.At Port Moody species of the family Staphylinidae, whose members are often associated with moss or leaf litter, are the most abundant fossils present. Other specimens included open-ground beetles of the family Carabidae, as well as weevils (Curculionidae) and bark beetles (Scolytidae), which inhabit conifers. The assemblage appears to represent an open forest-floor community. Some of the species in this site have distribution ranges that do not include the Port Moody area today, but do occur in the interior of British Columbia and at higher altitude near the coast. One of the most numerous species, Micropeplus laticollis Mäklin, occurs in duff of conifers including Picea engelmannii, Abies lasiocarpa, Pinus ponderosa, and Pinus contorta. These trees are characteristic of the subalpine forest. The insect assemblage suggests an in situ deposit, subalpine in nature, probably in a cool but dry environment that developed during the short episode when this part of the Fraser Lowland was ice free between the Coquitlam and Vashon ice advances.The beetle assemblage from Mary Hill Quadra sediments probably indicates that a bog environment existed at that time; however, the lack of specific identifications precludes detailed paleoclimatic interpretation.