A late Pleistocene steppe bison (Bison priscus) partial carcass from Tsiigehtchic, Northwest Territories, Canada Grant D. Zazula a, * , Glen MacKay b , Thomas D. Andrews b , Beth Shapiro c , Brandon Letts c , Fiona Brock d a Yukon Palaeontology Program, Department of Tourism & Culture, Yukon Government, PO Box 2703, Whitehorse, YT, Y1A 2C6, Canada b Prince of Wales Northern Heritage Center, PO Box 1320, Yellowknife, Northwest Territories, X1A 2L9, Canada c Department of Biology, The Pennsylvania State University, 326 Mueller Lab, University Park, PA 16801, USA d Oxford Radiocarbon Accelerator Unit, Research Laboratory for Archaeology & the History of Art, University of Oxford, Dyson Perrins Building, South Parks Road, Oxford, OX13QY, UK article info Article history: Received 27 March 2009 Received in revised form 12 June 2009 Accepted 15 June 2009 abstract A partial steppe bison (Bison priscus) carcass was recovered at Tsiigehtchic, near the confluence of the Arctic Red and Mackenzie Rivers, Northwest Territories, Canada in September of 2007. The carcass includes a complete cranium with horn cores and sheaths, several complete post-cranial elements (many of which have some mummified soft tissue), intestines and a large piece of hide. A piece of metacarpal bone was subsampled and yielded an AMS radiocarbon age of 11,830  45 14 C yr BP (OxA-18549). Mitochondrial DNA sequenced from a hair sample confirms that Tsiigehtchic steppe bison (Bison priscus) did not belong to the lineage that eventually gave rise to modern bison (Bison bison). This is the first radiocarbon dated Bison priscus in the Mackenzie River valley, and to our knowledge, the first reported Pleistocene mammal soft tissue remains from the glaciated regions of northern Canada. Investigation of the recovery site indicates that the steppe bison was released from the permafrost during a landslide within unconsolidated glacial outwash gravel. These data indicate that the lower Mackenzie River valley was ice free and inhabited by steppe bison by w11,800 14 C years ago. This date is important for the deglacial chronology of the Laurentide Ice Sheet and the opening of the northern portal to the Ice Free Corridor. The presence of steppe bison raises further potential for the discovery of more late Pleistocene fauna, and possibly archaeological evidence, in the region. Crown Copyright Ó 2009 Published by Elsevier Ltd. All rights reserved. 1. Introduction The unglaciated regions of Alaska (USA) and Yukon (Canada) contain some of the most productive Pleistocene vertebrate fossil localities in North America (Guthrie, 1990; Harington, 2003). This area is referred to as ‘‘eastern Beringia’’, the eastern province of the ‘‘mammoth-steppe’’ biome which stretched from England east- ward across the entire unglaciated northern hemisphere during Pleistocene cold intervals (Guthrie, 1990). The frigid, arid environ- ment of the mammoth-steppe was a Pleistocene Arctic refugium for the mammoth fauna: the now extinct community of large mammals characterized by woolly mammoths (Mammuthus pri- migenius), steppe bison (Bison priscus), and horses (Equus sp.). The eastern border of the mammoth-steppe is typically marked by the Richardson and Mackenzie Mountains as suggested by the rarity of Pleistocene vertebrate fossils from the glaciated terrain in the Northwest Territories (Fig. 1). Although a few Pleistocene mammal fossils have been recovered in the western Canadian Arctic east of the Yukon, little is known about the composition or chronology of these communities. In this paper we add to the limited data on Pleistocene mammals in northern Canada east of the Yukon, by reporting on a recently discovered partial steppe bison (Bison priscus) carcass from Tsiigehtchic near the confluence of the Arctic Red and Mack- enzie rivers, Northwest Territories (Fig. 1a). To our knowledge this is the first radiocarbon dated Pleistocene mammal with mummi- fied soft tissue discovered in the glaciated region of northern Canada. Data presented in this paper include an accelerator mass spectrometry (AMS) radiocarbon age, preliminary assessment of the carcass, morphometrics, and mitochondrial DNA sequences that confirm the presence of Pleistocene steppe bison in the Mackenzie River valley during the Lateglacial. These data are considered in light of previously discovered Pleistocene fossils in the Northwest Territories, the glacial chronology of the western * Corresponding author. Tel.: þ1 867 667 8089; fax: þ1 867 667 5377. E-mail address: grant.zazula@gov.yk.ca (G.D. Zazula). Contents lists available at ScienceDirect Quaternary Science Reviews journal homepage: www.elsevier.com/locate/quascirev 0277-3791/$ – see front matter Crown Copyright Ó 2009 Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.quascirev.2009.06.012 Quaternary Science Reviews 28 (2009) 2734–2742