Possible Human Interaction in a 33,000-Year-Old Lestodon Armatus Lesion in Uruguay: Notes on Early Evidence of Humans in the Americas and Their Impact on Megafaunal Extinction

Abstract

This paper discusses an archaeological finding at Arroyo del Vizcaíno (Uruguay) (Fariña et al. 2025), where a deep conical perforation was identified in the calcaneus of a Lestodon armatus specimen, an extinct ground sloth. The 41 mm deep by 21 mm diameter lesion was analyzed using Computed Tomography scans, silicone casting and microscopic wear and residue analysis. The authors propose that this perforation may have been caused by a blunt object, possibly made of hardened wood, bone, or ivory, used forcefully by humans approximately 33,000 years ago. This hypothesis is supported by the type of residues identified, the impact’s morphology, the entry angle (60° relative to the horizontal plane), and the estimated energy needed to produce the injury (over 120 J), ruling out natural or animal causes. This supports the theory of human presence in America before the Last Glacial Maximum (LGM) and its potential role in the extinction of the megafauna.