Radiocarbon dating and isotopic palaeoecology of Glossotherium phoenesis from the Late Pleistocene of the Santa Elina rock shelter, Central Brazil

Abstract

The Santa Elina rock shelter (Central Brazil) stands out with two human occupation layers with ground sloth fossil remains from the Late Pleistocene. Here, we explore the palaeontological aspect of this site. We update the taxonomic assignment of the ground sloth found in the shelter to Glossotherium phoenesis. Radiocarbon dating performed on bioapatite (14Cbioapatite) from two tooth specimens reveal the minimum ages of 14 944–15 239 cal a bp (unit II2) and 22 339–22 534 cal a bp (unit III4), which were converted to collagen using a novel approach and presented the calibrated ages of 17 450–17 906 cal a bp (14Ccollagen = 14 547 ± 40) and 25 994–26 396 cal a bp (14Ccollagen = 22 042 ± 40). We reinforce the chronology of the oldest unit of Santa Elina with material culture in association with megafauna bones to the Last Glacial Maximum. Carbon isotopic signatures suggest a mixed feeding diet for both specimens. The most recent ground sloth presents a higher isotopic value (δ13C = −1.8‰) and narrower niche breadth (BA = 0.50) than the oldest one (δ13C = −3.3‰; BA = 0.74). We conclude that G. phoenesis lived in an arboreal savanna habitat during the phases studied. Slightly different oxygen isotopic values (δ18O = 26.2‰ and 27.9‰) might suggest a decrease in humidity over time. Our results provide insights into the palaeoecology of the tropical Pleistocene G. phoenesis and the palaeoenvironmental setting of Santa Elina when occupied by early humans and megafauna during the Late Pleistocene.

Evidence of artefacts made of giant sloth bones in central Brazil around the last glacial maximum

“…Dated mineral pigments and bonfire structures associated with stone tools and megafaunal remains found in the shelter include Late Pleistocene to the Holocene ages [10,14]. The only Pleistocene megafauna present in the shelter are two extinct giant ground sloths of the species Glossotherium phoenesis Cartelle, De Iuliis, Boscaini & Pujos 2019 [15], in two different archaeological layers. Although the bone remains occur in an archaeological context with other material elements of the culture, such as stone tools, they are found in a poor state of preservation, and we could not macroscopically observe any carnivore or cut marks.…”