A PALEOENVIRONMENTAL ANALYSIS USING FOSSIL INSECTS IN QUATERNARY SITES IN INDIANA AND OHIO: 9,000 TO 44,000 YRS BP

Numerous biological records have been used to infer past climate and environment. Insects are useful indicators of environmental changes because they are highly responsive to environmental change. My study examined four sites in Ohio and Indiana that are dated from the middle Wisconsinan to the late Wisconsinan and early Holocene: Bergendorfer IN (44000 - 21640 BP), Sidney OH (40000 BP), Snyder IN (19700 BP) and Sheriden Pit OH (11557 - <9844 BP). The main focus is on the insect Order Coleoptera (beetles) and how coleopterans may be used as paleoenvironmental indicators. Collection and processing of specimens followed standard techniques. Habitat types for insect species and genera were collected from recent publications. Jaccard and Dice coefficients were used to differentiate insect assemblages. The Mutual Climate Range method was used to determine temperature ranges for the sites. Diversity ranged from very low (Sheriden Pit) to high (Bergendorfer Low) in the sites and horizons. All sites are separate assemblages at genus and family level. Insect habitat, modern biogeography, and MCR envelopes were used for interpretation of the sites’ paleoenvironment. A moist to wetland habitat persisted in the Indiana-Ohio border region throughout the studied interval, although the temperatures indicate repeated shifts from boreal to slightly warmer conditions. Bergendorfer was most likely a moist to wet, boreal habitat. Sidney site was near water but no general biome could be determined. Bergendorfer Low may have been a boreal to boreal-tundra ecotone and a very wet environment. Bergendorfer High was most likely a moist to riparian boreal habitat. Snyder was most likely a boreal forest with spruce and bogs. Sheriden Pit was moist at the time Arpedium cribratum was buried and slightly cooler than today.

This study has demonstrated the utility of insects, especially coleopterans, in determining paleoenvironments. The data correlates quite well with previous pollen and invertebtrate studies done at the same sites, and general glaciation patterns during the time period. More studies of ancient insect assemblages will further detail regional habitat shifts throughout the Late Quaternary.