A late Pleistocene steppe bison (Bison priscus) partial carcass from Tsiigehtchic, Northwest Territories, Canada
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 eastward across the entire unglaciated northern hemisphere during Pleistocene cold intervals (Guthrie, 1990). The frigid, arid environment 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 primigenius), 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 Mackenzie rivers, Northwest Territories (Fig. 1a). To our knowledge this is the first radiocarbon dated Pleistocene mammal with mummified 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 Canadian Arctic and the northern opening of the “Ice Free Corridor” (IFC) as a mid-continental dispersal route between the Cordilleran and Laurentide Ice Sheets during deglaciation.
Section snippets
Pleistocene fauna of the Northwest Territories
In comparison to the adjacent unglaciated regions of the Yukon, few Pleistocene mammal fossils have been recovered from the Northwest Territories (Harington, 2003; Fig. 1a). The rarity of previous Pleistocene fossil discoveries in the region highlights the significance of the Tsiigehtchic bison for our knowledge of late Pleistocene mammal biogeography. Rare Pleistocene fossils include those recovered from the Mackenzie Delta and Beaufort Coastlands on the mainland, the islands off the Beaufort
Discovery of the Tsiigehtchic bison
The partial fossil bison carcass was recovered from a west-facing steep outcrop overlooking the Arctic Red River at the community of Tsiigehtchic, Northwest Territories (67°, 36′, 34″N; 133°, 44′, 50″W, 32 m a.s.l.) by local resident Shane Van Loon in early September, 2007. Mr Van Loon collected several pieces of the bison carcass after he observed them melting out of permafrost-laden gravel and sand sediments between September 5 and 8, 2007. The bison carcass was released from the frozen
Site stratigraphy
The site of the fossil bison discovery is locally known as “Church Hill” as it lies directly underneath the Roman Catholic Church grounds and cemetery (Fig. 2). The outcrop is approximately 35 m in height with approximately the upper 8 m representing unconsolidated Quaternary sediments. The exposure of frozen, unconsolidated sand and gravel (with well-rounded cobbles up to ∼30 cm in diameter) contained a large bowl-shaped retrogressive thaw scar (∼18 m in depth into the outcrop) above the contact
Glacial retreat, the Ice Free Corridor and Lateglacial palaeoenvironments
The radiocarbon date of 11,830 ± 45 14C yr BP (OxA-18549) from the Tsiigehtchic bison has important implications for the deglacial chronology of the Laurentide Ice Sheet (LIS) (Fig. 1b). The community of Tsiigehtchic, located at the confluence of the Mackenzie and Arctic Red rivers, is situated well within the all-time Late Wisconsinan maximum limit of the LIS (Dyke et al., 2003). According to the glacial chronology of Duk-Rodkin (1999), the LIS advanced across the western Arctic to its maximum
Summary and conclusions
Our report here of an exceptional partial steppe bison carcass from Tsiigehtchic adds a crucial piece of data to our knowledge on the late Pleistocene faunas and deglacial chronology of the Northwest Territories. This is the first report of mummified soft tissue from a Pleistocene mammal discovered in the area covered by Pleistocene glaciers in northern Canada and is the first radiocarbon dated steppe bison from the Mackenzie River valley. Mitochondrial DNA from the Tsiigehtchic bison carcass
Acknowledgements
We thank Shane van Loon for his keen eyes that led to the steppe bison discovery. We are grateful to: Alestine Andre and Itai Katz for hosting GM and GZ during their stay in Tsiigehtchic and the community of Tsiigehtchic for their interest and support for this research; Ingrid Kritsch, Alestine Andre and Sharon Snowshoe of the Gwich'in Social and Cultural Institute for logistical support; Dean Cluff with ENR-North Slave District for storing the fossil temporarily in Yellowknife. Valerie
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A detailed life history of a pleistocene steppe bison (Bison priscus) skeleton unearthed in Arctic Alaska
2020, Quaternary Science ReviewsEarly colonization of Beringia and Northern North America: Chronology, routes, and adaptive strategies
2017, Quaternary InternationalThe Yukagir Bison: The exterior morphology of a complete frozen mummy of the extinct steppe bison, Bison priscus from the early Holocene of northern Yakutia, Russia
2016, Quaternary InternationalCitation Excerpt :It also lies within the lower limit of the Late Pleistocene bison horn core tip spread designated as Bison priscus by McDonald (1981) (751–1064 mm, mean 888 mm) that comprised the bison from mid- and high latitudes of Eurasia and Beringia to a few sites in midlatitude and tropical North America. When compared to the most complete specimens of the extinct species, the spread of the sheath tips of the Yukagir Bison appeared considerably smaller than that of the terminal Late Pleistocene (11,830 ± 45 BP) Tsiigehtchic Bison (940 mm) discovered in the Mackenzie River Valley, Yukon (Zazula et al., 2009) and the adult male Blue Babe (922 mm) from Alaska (∼36,000 BP; Guthrie, 1990). If compared to the modern Wood bison, the Yukagir Bison sheath and horn core sizes and core lengths are between of 4.5 year old males and adult males of this species, but the horn's spread is significantly higher than that in average adult Wood bison, indicating the species differences (Table 2).
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2015, Quaternary Research (United States)Citation Excerpt :Because the majority of published data include only the hypervariable control region, we extracted this portion of the mitochondrial genome for further work (~ 580 base pairs). We aligned the Rauchua bison to a larger data set of 172 bison mitochondrial control region sequences (Shapiro et al., 2004; Zazula et al., 2009; Lorenzen et al., 2011). We assumed the GTR + G model of nucleotide substitution and the skygrid model of the coalescent process (Gill et al., 2013), and used the ages of each ancient bison, calibrated using the IntCal13 calibration curve (Reimer et al., 2013), using OxCal (Bronk Ramsey, 2009), to inform the molecular clock rate.