NEW RADIOCARBON DATE FOR CARIBOU (RANGIFER TARANDUS) REMAINS IN MICHIGAN’S LOWER PENINSULA

Caribou are a circumpolar cervid species with a long history of use by and interaction with humans. In the Pleistocene, cold climates and advancing continental ice sheets allowed this species to range as far south into North America as South Carolina, though present-day caribou are typically occur above the 45^th parallel. Extirpation of caribou from what would become the United States was an event that occurred across the Pleistocene-Holocene transition (11,700 YBP), though the event was not complete in the northern and northeastern part of the country until the late Holocene. Michigan’s Lower Peninsula preserves a record of this gradual Pleistocene colonization of caribou in northern latitudes and their Holocene extirpation from southern latitudes, with fossils dating from approximately 13,000 to 1,200 YBP. Transgressions and regressions of lakeshores may have played a role in the occurrence of caribou or the preservation of their remains. Unfortunately, much of the biogeographic history of caribou in Michigan is based on fossils that were primarily recovered from the southeastern part of the Lower Peninsula, which wildly varies in terms of its Holocene floral history from the northwestern portion. An antler recovered from Manistee County, Michigan was given by a member of the public to the U.S Forest Service in 2000 but went unreported until 2015. Here, we present radiometric data from this antler: it reveals that, despite being found significantly farther north and west of most Pleistocene examples of caribou in Michigan’s Lower Peninsula, the fossil was deposited 11,370 (+/- 40) YBP. This suggests that Michigan, and probably much of the Great Lakes Basin, was widely inhabited by caribou around the time of the Pleistocene-Holocene transition. It could further suggest that many of the conclusions drawn about caribou in the Lower Peninsula were applicable to the rest of the state despite other samples coming from a relatively localized area. One reason for this might be that Michigan’s Lower Peninsula, despite variation in flora during the late Holocene, featured a surprisingly uniform forest during the Pleistocene and earliest Holocene: local pollen data suggests that a spruce-and-pine-dominated forest persisted across most of the Lower Peninsula during the end of the Pleistocene, and southeastern Michigan varies only in that oaks may have been more present as well.