MEGAHERBIVORE DYNAMICS AT THE PLEISTOCENE-HOLOCENE TRANSITION IN EASTERN BERINGIA USING MULTIPROXY PALAEOENVIRONMENTAL RECORDS

Pleistocene-Holocene extinctions are a long-recognised feature of North American megafaunal loss. One major challenge of reconstructing megaherbivore dynamics at this transition is the scarcity of skeletal remains. Subsequently, the spores of coprophilous fungi preserved in lake sediments have been shown to successfully indicate the presence of megaherbivore populations. This study presents the first multiproxy analysis from Yukon Territory combing coprophilous fungi and pollen records from Gravel Lake (ca. 15 000 – 9400 cal yr BP) with radiocarbon dated megaherbivore remains from East Beringia spanning the last 25 000 years. A decline in spores of Sporomiella, Sordaria, Cercophora, Delitschia, Gelasinospora and Coniochaeta from Gravel Lake indicate the local extirpation of megaherbivores at ca. 11 000 – 10 400 cal yr BP. Bone records concur with this conclusion with the exception of mammoth and horse populations that are lost from the record 2000 years earlier at ca. 13 000 cal yr BP when palynological assemblages indicate some of the last environments contiguous with the mammoth steppe in this region. The remaining taxa (bison, caribou, elk, moose and muskox) are all extant in Yukon Territory indicating the reestablishment of their populations despite dramatic restructuring of northern ecosystems at the end of the Pleistocene.