Modern Guanacos (Lama guanicoe) Killed by Winter Stress in Southern Patagonia (Argentina): Taphonomic and Archaeological Implications

Abstract

The mass mortality events of ungulates in different environments offer valuable biological and taphonomic information with direct implications for understanding the regional archaeological record. This paper studies modern guanacos (Lama guanicoe) killed by winter stress in the Coyle-Gallegos interfluve (southern Patagonia, Argentina) during 2020. The aims of this work are a) to characterize the biological and taphonomic signatures of guanaco deaths caused by winter stress; b) to examine the burial potential of these bone assemblages and the chances of producing spurious associations with the archaeological material; and c) to discuss the impact of the glut of resources offered by these carcass accumulations for past hunter-gatherer adaptations. Transect sampling was conducted in three sectors with different geomorphologic and topographic characteristics: high plains, hillside in the plains, and hillside in the canyon. Carcasses were examined in the field, recording location, sex, age, and taphonomic variables. A total of 497 guanaco carcasses were recorded, including 164 isolated and 333 distributed in 42 concentrations. Most of the carcasses were concentrated at places that offered some protection, such as shrubs and wind-shielded hillsides. The total sample of guanacos shows an attritional mortality profile, where the weakest individuals were the most affected, especially those younger than one year. Carcasses were modified by carnivores, possibly foxes, contributing to disarticulation and bone dispersal. Bone burial two years after dead was minimal and is not expected to occur in the long term due to the low sedimentation rate. The three surveyed sectors observed overlapping of modern guanaco bones and lithic artifacts. More overlapping is expected at the bottom of the canyon, where there is a continuous distribution of archaeological material, and sedimentation allows the burial of naturally deposited bones. Current records indicate that massive deaths of guanacos caused by winter stress are frequent in southern Patagonia. These deaths were probably more common in the past, especially during neoglacial events, offering a good opportunity for obtaining low-cost animal resources for past hunter-gatherers.