The use of phosphorus to determine evidence of bone on a possible high elevation bison jump

Abstract

The Dinwoody Bison Jump (48FR7682) is located at 3,350m/11,000ft in the Wind River Mountains in the Greater Yellowstone Ecosystem of Wyoming. The site consists of an 8 km2 grazing area, a 1.6 km long system of three converging drivelines comprised of stacked stone cairns and blinds with doglegs near the jump, an obscuring ridge, a scarp/kill site, a butchering area with thousands of pieces of debitage, and a shaman structure. Optically stimulated luminescence dating of built features in the drivelines indicates that the site was used between about A.D. 1310 - 1870. The jump is associated with a 5 km2 complex of lodge pad villages and campsites. Diagnostic artifacts from Folsom through Late Prehistoric and into the Protohistoric have been documented in those sites. The jump complex has all the key characteristics of what Kornfeld et. al (2010), defined as a bison jump. Nevertheless, because the site is extraordinarily high and lacks a bone bed some have questioned its interpretation as a bison jump. Central Wyoming College (CWC) researchers documented the presence of prehistoric bison skeletal remains at multiple locations above 3,050 m/10,000 ft. over the entire length of the Wind River Mountains. Faunal remains are absent at the Dinwoody jump because only about 15 cm of acidic soil exists above bedrock in the butchering area at the foot of the jump, and the jump faces southwest toward the prevailing winds so is heavily impacted by weather. Consequently, there is no bone preservation. Soil analysis for the fungus sporormiella failed to produce evidence of herbivore decomposition (Petersen 2017). Phosphate analyses of soil samples collected from the butchering area produced results similar to soil analyses from the extensive bonebeds at the nearby Wiggins Fork Jump. Elevated calcium phosphate levels in soils from the suspected butchering areas compared to control samples from surrounding areas suggests decomposition of discarded bone in the Dinwoody jump butchering area.