Giant sloth, source of adornment for prehistoric Brazilians

The Santa Elena rock shelter, in Mato Grosso, provides a fascinating summary of human occupation in Brazil. Apart from the very rich multi-secular figurative cave paintings, they have given archaeologists less clear evidence of a much earlier presence of our species in these regions, in the form of bone and stone tools. But also intriguing “pearls” from giant sloths, animals that have long since become extinct. A study published July 12 in Proceedings of the Royal Society b Thus presents the analysis of three perforated osteoderms found in the oldest layers of the site, dated from 25,000 to 27,000 years ago.

osteoporosis? This term designates Tiny bony balls found in the skin of some giant sloths, possibly the armored remnants of their ancestors.explains François Bogos. This paleontologist of the Argentine National Council for Scientific and Technical Research (Conicet), an organization similar to the French National Center for Scientific Research (CNRS), was not involved in the Santa Elena study, but he does specialize in phoenesis GlossotheriumKinds of giant sloths out there. “These ossifications within the dermis can act as an integrated shield.”, he describes. They were vascular, suggesting they could also play a role in thermoregulation for this family of animals, the largest of which can reach several tons — they were part of the “megafauna,” a group of mammals of considerable size, the last of which disappeared 11,000 years ago. to 12,000 years ago in America.

In Santa Elena, more than 4,000 osteoderms were found spread over an area of ​​15 metres.² from excavations »declares Agueda Vialou (National Museum of Natural History of Paris, Federal University of Bahia), who managed these from 1984 to 2005. They discovered two specimens of Glossotherium, one in a layer dating back 12,000 years, and the other in an older layer, over 25,000 years old. In this sense, three osteoderms have attracted the attention of archaeologists, because of the holes they have attributed to humans – Agueda and her husband, Dennis Fiallo, have estimated since the end of the 1990s that they could be used as ornaments or pendants.

The new study aimed to remove doubts about the intentional origin of these perforations, thanks to work on the clothing using several imaging techniques. “We wanted to be as certain as possible that they cannot be caused by physical and chemical processes and animal interventions.”Loïc Bertrand, paleochemical chemist and director of research at the Ecole Normale Supérieure Paris-Saclay, specifies. So the pieces came from Brazil to be subjected to x-rays from the European Synchrotron Radiation Facility in Grenoble and to photoluminescence analyzes to assess the contemporaneity of the holes and the visible polishing on the osteoderms. It was also compared with experimentally modified fossil osteoderms.

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