New Radiocarbon Dates from the Late Paleoindian Cody Complex Component at the Lamb Spring Site, Douglas County, Colorado

ABSTRACT Extant collections, such as those from the Lamb Spring site near Denver, Colorado, provide the opportunity to fine-tune existing chronologies through the application of new techniques. Here we present three newly obtained, high precision AMS radiocarbon dates – 9425 ± 20, 9445 ± 25, and 9470 ± 25 radiocarbon years BP (averaging 9443 radiocarbon years BP) – on bison killed by the site’s Cody complex inhabitants. These new dates are older than the previously reported ages from the Cody deposit and provide a more reliable assessment of the component’s age. Dietary stable carbon isotopes obtained on the dated samples suggest the bison kill (or kills) likely occurred during a time when warm-and-dry-tolerant C4 grasses were increasing relative to the previously dominant, cool-weather-tolerant C3 grasses.