End of the Pleistocene: elk-moose (Cervalces) and caribou (Rangifer) in Wisconsin

Abstract

Fossils of caribou (Rangifer tarandus) and elk-moose (Cervalces scotti) were found in a Wisconsinan–Holocene outwash bog on Kluck Farm, near Bevent, Marathon County, Wisconsin. These caribou fossils are the northernmost records for the state, and the extinct Cervalces the 1st known from the state and northernmost record for the species. The site is located at the mapped ice front of the Green Bay Lobe of the late Wisconsinan Valder's Readvance, which was present between 12,500 and 11,500 years before present. Examination of accelerator mass spectrometry 14C data indicated that the elk-moose was older than the caribou by 1,6000–1,700 years. Matching the radiocarbon dates with those of nearby sites and to their pollen records helps to clarify the nature of climatic conditions and corresponding plant communities at the upper Pleistocene boundary. The pattern of replacement of taiga forest southward and westward of the Green Bay Lobe to warmer, open-range conditions, with invading prairie, pine (Pinus), and deciduous trees, resembles changes that took place earlier, when glaciers and cool climate occurred south of the late Wisconsinan ice fields. Perhaps cursorial carnivores preyed on the large cervids, which were made more visible in openings of the taiga and grassland and by the typical succession expected of boreal wetlands to dry prairie or park-like savanna copses of spruce (Picea), oak (Quercus), and pine.