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Important Pleistocene Vertebrate Sites in the Great Lakes Region This chapter describes some important Pleistocene vertebrate sites in the Great Lakes region . Sites will be presented in chronological order from older to younger Pleistocene sequences . Emphasis will be on the larger sites that have yielded large vertebrate faunas and/or especially important species. For instance, the Late Wisconsinan Sheriden Pit Cave Site in northwestern Ohio will be featured because of its extensive faunal list as well as its important species. On the other hand, the Sangamonian Hopwood Farm Site in south-central Illinois will be discussed mainly because of the presence of a single important species, the giant land tortoise (Hesperotestudo crassiscutata). ONTARIO The most important Pleistocene sites in Ontario occur in the southern part of the province near Ottawa and Toronto. In the Toronto region, one finds the most extensive superimposed sequence of Pleistocene vertebrate faunas anywhere in the Great Lakes region. Here, superimposed Sangamonian, Early Wisconsinan, Middle Wisconsinan , and Late Wisconsinan sites occur, often with glacial tills above and below them. The most important 146 Ontario Pleistocene vertebrates are the widespread mastodont and mammoth fossils and the large marine mammals of the Champlain Sea deposits near Ottawa. The most disappointing aspect of the Ice Age vertebrate fauna of Ontario is how few Pleistocene records of amphibian and reptiles exist. Sangamonian Site (Rancholabrean) Don Formation, Don Valley Brickyard Site, Toronto, York County, Ontario. The Don Valley Brickyard Site in Toronto is the type locality for the Sangamonian Don Formation, which is underlain by the York Till of Illinoian age and overlain by the Scarborough Formation of Early Wisconsinan age. The fossils from the Don Valley Brickyard were collected from a 25-foot thick layer of stratified, cross-bedded clay and sand. Cross-bedding indicates that these relatively fine sediments were deposited by relatively slow currents that moved over a shallow drop-off. Mollusk shells, wood, and leaf fossils, as well as pollen and diatoms (tiny protists with silica shells), suggest that the sediments of the Don Formation were deposited in a freshwater bay of a very large Pleistocene lake that was at least 60 feet higher than Lake Ontario is today. Pollen taken from sediments at the bottom of the Don Formation suggests that the plants existed in a temperate climate that was as much as 5 degrees F warmer than at present. But pollen and faunal evidence from the upper part of the Don Formation beds indicates that a cooling trend was in progress. The vertebrate fauna consists of the following animals : trout and whitefish (Salmonidae), pike or muskellunge (Esox sp.), shiner (d. Notropis sp.), channel catfish (Ictalurus punctatus), burbot (Lata Iota), yellow perch (Perca (lavescens), Probable freshwater drum (d. Aplodinotus grunniens, a member of the sculpin family (Cottidae), brown bear (Ursus arctos ), Scott's moose (stag moose) (Cervalces scotti), white-tailed deer (Odocoileus sp.), woodchuck (Marmota monax), and giant beaver (Castoroides ohioensis ). Since Sangamonian-age fossils are rare in the Great Lakes region, these Don Formation fossils are of considerable importance, especially since they occur in such a northern area. This is one of the earliest records of the giant beaver. It is surprising that there have been no reptile fossils, especially turtle shell elements, recovered from the Don Formation, particularly from the lower beds where temperatures warmer than at present were indicated. The lack of turtle bones might indicate that the freshwater bay lacked the dense aquatic vegetation that is preferred by most aquatic turtle species. References. Coleman (1933), Karrow (1969), Harington (1978, 1990), Karrow et al. (1980), Eyles and Williams (1992). Late Sangamonian or Early Wisconsinan Site (Rancholabrean) Innerkip Site, Oxford County, Ontario. The Innerkip Site lies about 2 miles from the village of Innerkip about 30 miles northeast of London on a tributary of the Thames River. This site, unlike the Don Valley Brickyard Site in Toronto, is not a part of an extensive stratigraphic sequence. The fossils were recovered from an isolated peat deposit that represents a Pleistocene bog. The peat rests on silt and clay and is overlain by organic muds, followed in sequence by clay, silt, and glacial tills. Based on a radiocarbon date of over 50,000 B.P. on black organic muds and floral and faunal evidence, a Late Sangamonian or Early Wisconsinan age is suggested. Plants identified from the Innerkip Site include pollen, mosses, wood fragments, and seeds. Insects from the site include ants, true bugs, caddisflys, and beetles. The plant remains suggest that the dominant vegetation of...

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