Late Archaic bison hunters in northern Colorado : 1997-1999 excavations at the Kaplan-Hoover bison bonebed (5LR3953)

Limited excavations at a Late Plains Archaic arroyo trap along the Cache la Poudre River near Windsor in northern Colorado have exposed the remains of an estimated 200 bison. The bonebed was uncovered during construction activities, which removed an estimated 4 m of sediment from above the upper surface of the bonebed. Partial excavation of an 18.5 m2 cross-sectional portion of the arroyo has produced an assemblage of over 4000 bison bones. An AMS date on wood charcoal and a standard radiometric age from bone collagen provided statistically similar dates and yield an averaged uncalibrated radiocarbon age of 2724±35 RCYBP. The number of stone tools recovered is low, with only nine corner-notched projectile points and point fragments, several scrapers and flake tools, and over 120 resharpening flakes. Patterns of mandibular molar eruption and wear indicate a single early fall kill. Human utilization of many of the carcasses was limited, with very few of the marrow bones fractured or removed from the kill site. Based on skeletal element counts, the carcass segments most frequently taken from the kill were rib slabs, thoracic vertebrae, scapulae, femora, and lumbar-sacral units. Cutmark frequencies support this interpretation. The most common locations for butchering marks are on the thoracic spines, rib blades, and mandibular symphyses. After humans abandoned the site, carnivores extensively modified the remaining carcass segments. Subsequent burial of the bonebed included fluvial transport and re-orientation of many of the bones within the old arroyo. The project has emphasized incorporating public interaction and education into the research program.