Alan V. Morgan

Stable isotope, fossil Coleoptera and pollen stratigraphy in late Quaternary sediments from Ontario and New York State

Stable oxygen isotope contents of marl deposits and molluscs from lakes and ponds in northern New York State (U.S.A.) and southwestern Ontario (Canada) are remarkably uniform for carbonates formed between about 12,600 yr B.P. and 2000 yr B.P.. This suggests relatively stable climatic conditions with slowly increasing temperatures throughout this time span, an observation already indicated by fossil beetle data; and re-confirmed by additional data presented in this paper. The variations seen in pollen diagrams probably are related to plant colonization, and climatic parameters such as changing humidities. This contrasts sharply with observations made in Europe where variations in pollen diagrams are paralleled by changing 18O contents in lacustrine marls and molluscs which clearly reflect climatic/temperature changes during late glacial and early postglacial times (13,500–9000 yr B.P.). 13C contents in marls and molluscs are not directly dependent on climatic change but reflect changing environments with varying aquatic and terrestrial carbon contributions.

Changes in late Quaternary vegetation and insect communities in southwestern Ontario

Abstract The Gage Street site in Kitchener, Ontario, is a peat/marl sequence representing continuous lacustrine sedimentation from the time of deglaciation (ca. 13,000 yr B.P.) through 6900 yr B.P. Insect, pollen, and plant macrofossil remains isolated from the sediments indicate that from ca. 13,000 to 12,500 yr B.P. the region was characterized by parkland-tundra vegetation existing within thermal conditions more analogous to those today of the midboreal forest. The transition from parkland to coniferous forest at ca. 12,500 yr B.P. occurred within a climate that was only gradually warming. By the time of the spruce/pine transition at 10,500 yr B.P., an insect fauna had become established that is typical of southwestern Ontario today. The replacement of this fauna at ca. 8400 yr B.P. by one characteristic of the lowlands of the east-central United States represents the beginning of Hypsithermal conditions in southern Ontario. Vegetation and insects indicate that the climate continued to gradually warm through the mid-Holocene.

Invertebrate fossils (Insecta: Trichoptera, Diptera, Coleoptera) from the Pleistocene Scarborough Formation at Toronto, Ontario, and their paleoenvironmental significance

Abstract Larval caddisfly, chironomid, and beetle remains have been recovered from the Pleistocene Scarborough Formation in the Toronto region of southern Ontario. Three stratigraphic levels were sampled at the northeastern end of the Scarborough Bluffs; the youngest horizon yielded 16 chironomid taxa, 33 caddisfly taxa, and 28 beetle taxa, whereas the two older levels yielded somewhat less diverse assemblages. Only one taxon in each of the caddisfly and chironomid groups was identified from the presumed correlative beds at Woodbridge, Ontario, but numerous beetle fragments were recovered, several of which have been specifically identified and match species found previously in the upper part of the Scarborough Formation. The youngest sampled assemblage in the Scarborough Formation at the northeastern end of the Scarborough Bluffs is interpreted as indicating cool climatic conditions in a boreal forest environment, given the present-day distributions and feeding habits of these river, lake, and terrestrial taxa. The mean July temperature at this time was probably about 15°C, as compared to the present-day value of 20.5°C. The forest was poorer in deciduous species during deposition of the older part of the formation as preserved here. These results agree well with previous interpretations based on plant remains. We suggest that both aquatic and terrestrial insects are good indicators of macroclimate.

Climatic implications of D/H ratios in beetle chitin

Abstract Hydrogen isotopic analyses of beetle chitin demonstrate the potential for development of a palaeoclimatic tool that can be used to complement current palaeoentomological methods. Hydrogen and carbon, incorporated into the polysaccharide component of insect exoskeleton, are believed to be ultimately derived, via the food chain and metabolic processes, from diet carbohydrates constructed in plants from carbon dioxide and environmental water during photosynthesis. Isotopic data from this study and from carbon isotopic examinations of the same laboratory reared species support this assumption. Reproducible hydrogen isotope results, obtained from a simple nitration of chitin, demonstrate small interspecific and intraspecific variation in beetles of different habit. Chitin nitrate samples analysed from sites across North America vary in a similar manner to D/H ratios measured in cellulose nitrate when compared with environmental temperature. This may be particularly true when temperatures above freezing are considered.

Glacial Lake Levels and Eastern Great Lakes Palaeo-Indians

This article investigates changing lake levels in the late Pleistocene eastern Great Lakes inorder to gain insights into the Early Palaeo-Indian occupations. Significant new informationbearing on lake level history is provided, notably the first well-documented deposits of a highwater level above modern in the ca. 11,000–10,300 B.P. period in the southern Lake Huronbasin. The lake level information, along with paleoenvironmental and site data, reinforcessite age estimates to the 11th millennium B.P.; suggests significant numbers of sites have beeninundated by rising water levels; provides specific informationonthe settingofarchaeologicalsites such as placing the Parkhill site adjacent to a large lake estuary; indicates reasons forthe attractiveness of shorelines to Palaeo-Indians including persistence of more open areasconducive to higher game productivity; and points to ideal areas for future archaeologicalsite survey, particularly in the Lake Erie drainage. 2000 John Wiley & Sons, Inc.

Paleoenvironmental implications of a late glacial insect assemblage from northwestern New York

Abstract The Winter Gulf site near North Collins, New York is a 0.8-m sequence of organic detritus dated at approximately 12,700 yr B.P. A 260-kg sample produced over 500 identified individuals representing five orders of insects. Three insect zones were recognized, the lowest representing an open mire with sparse numbers of carices and other sedges; aquatic beetles were rare, and no trees were in the vicinity of the sample site. The middle zone indicated an extensive marsh or moist meadow environment with spruce nearby. The upper zone represented a mixed riparian and spruce forest insect assemblage. The results of the Winter Gulf insect analyses support published hypotheses that the site was probably a protected embayment of early lake Warren. Although the flora at the site has been previously interpreted as representing parkland tundra, temperature analyses of the fauna indicate that the thermal conditions were much warmer than parkland tundra regions of North America today. These results have important significance for the region immediately south of the Laurentide Ice Sheet during this period of the Late Wisconsinan.

On the gibbulus Group of Anotylus, and fossil occurrences of Anotylus gibbulus (Staphylinidae)

Abstract. The gibbulus Group of the genus Anotylus is diagnosed and the grounds for believing the group to be monophyletic discussed. The habits and present‐day relictual distribution of this Old World group are summarized.

A postglacial coleopterous assemblage from Lockport Gulf, New York

Abstract The Lockport Gulf site near Lockport, New York, is a 1.9-m sequence of organic-rich marls having a basal date of approximately 10,920 yr B.P. Six bulk samples with a combined weight of 48 kg produced over 780 individual fossil insects representing five orders, as well as molluscs and abundant plant macrofossils. Coleoptera were represented by 24 families. Several major beetle groups (Carabidae, ground beetles; Hydrophilidae, water scavenger beetles; Elmidae, riffle beetles; Staphylinidae, rove beetles; and Scolytidae, bark beetles) indicate a riffle-and-pool stream, surrounded by marsh, with open riparian habitats and nearby trees. Two zones were recognized based on the Coleoptera assemblages. The Zone 1 fauna (ca. 10,920–9800 yr B.P.) was dominated by boreal forest taxa with abundant bark beetles indicating the presence of spruce trees. In Zone 2 (ca. 9700-9100 yr B.P.) the combination of species with a restricted modern distribution in the Great Lakes-St. Lawrence Forest region and pine and deciduous tree inhabitants suggests a change in vegetation by 9700 yr B.P. Thermal estimates from a faunal analysis indicate that the climatic conditions were stable across the spruce-pine transition, with the mean July temperature in the range of 16° to 18°C.

Paleoentomology and paleoecology of a possible sangamonian site near Innerkip, Ontario☆

Abstract A stream section near Innerkip, Ontario, exposes several meters of organic silts and peaty detritus beneath two late Wisconsinan tills. Radiocarbon dates provide a minimal middle Wisconsinan age of >50,000 yr B.P. A 250-kg bulk sample from the peat stratum was processed for vertebrates, plant macrofossils, and insects. Vertebrate remains include teeth from deer, muskrat, and vole as well as plates from a turtle shell. At least 6000 insect fragments from a minimum of 19 Coleoptera families were identified. The most common groups are hydrophilids and dytiscids (water beetles), curculionids (weevils), staphylinids (rove beetles), and carabids (ground beetles). The majority of identified beetles are associated with fresh water as aquatic predators, scavengers, or grazers, while others prefer hygric substrates and moist plant litter. The large number of plant-dependent beetles, the numerous floating and emergent aquatic plant seeds, and the presence of the associated vertebrates point toward a locally rich and varied flora and fauna, probably deposited in a well-vegetated pond. The modern distributions and ecologies of the identified fossil insects suggest temperatures similar to those found in southern Ontario today. On these grounds the Innerkip peat represents either a very warm interstadial or a possible interglacial deposit. If the latter is true this is the second presumed Sangamon-aged site known in southern Ontario.

A Wisconsinan interstadial arctic flora and insect fauna from Clarksburg, southwestern Ontario, Canada

Abstract Radiocarbon dating and sedimentological, pollen, plant macrofossil, and insect analyses were performed on a subtill organic deposit in southwestern Ontario, Canada. Stratigraphic relationships and minimum radiocarbon dates suggest a Middle Wisconsinan age. The sedimentary sequence indicates a fluvial environment with a rising base level as an approaching ice-front dammed and produced a deepening proglacial lake. Eventually ice covered the site for much of Late Wisconsinan time. The fossil plants and insects indicate an open-ground, treeless landscape comparable to modern low to high arctic environments in Canada. The beetle fauna is dominated by members of the sub-genus Cryobius , and is associated with fossils of dwarf shrubs, Salix herbacea and Dryas integrifolia , and herbs such as Saxifraga oppositifolia .