Late Quaternary herpetofauna of the Central Great Lakes region, U.S.A.: Zoogeographical and paleoecological implications

Abstract

Late Quaternary herpetological records from the Central Great Lakes States of Michigan, Illinois, Indiana and Ohio allow for reflections on reinvasion of herpetological species into previously uninhabitable areas, as well as some comments on paleoclimate. Advances of the Wisconsinan Laurentide ice sheet obliterated herpetological habitat in all of Michigan as well as much of Illinois, Indiana and Ohio; it also restricted herpetological habitat in the southern parts of the three latter states. By about 15-14 ka BP a rich herpetofauna, similar to the one that occurs in the area today, and suggesting a moderate climate, occurred in southwestern Indiana. Turtle faunas in central Indiana (13-12 ka BP) and west-central Ohio (11-10 ka BP) suggest that warm summer climates existed in those areas at the time. On the other hand authentic reptile records are unknown from the Pleistocene of Michigan, and considering the pollen record, that state probably had a much colder climate during postglacial Late Wisconsinan times. A well-developed turtle fauna associated with temperate deciduous forest occurred in southern Michigan about 6 ka BP, and a rich herpetofauna, similar to the one that occurs in the area today, occurred in southwestern Indiana about 4 ka BP. This evidence suggests the possibility that the herpetological reinvasion of the Central Great Lakes region might have been nearly complete by Mid-Holocene times.