Giant sloth bone pendants are found in MT – 07/03/2023 – Science

Some of the oldest inhabitants of present-day Brazilian territory transformed the bones of a type of giant sloth into body ornaments, probably making a kind of pendant.

The conclusion comes from an analysis of the artifacts by paleontologists and archaeologists and is one of the most direct evidence of interaction between humans and giant Ice Age mammals ever found in Brazil.

The body adornments were found in the rock shelter of Santa Elina, in Mato Grosso.

The site also stands out for the very old dates obtained from charcoal fragments and other remnants, older than almost all other archaeological sites in the country. If the dating is correct, the artifacts were produced around 25,000 years ago, during the so-called Last Glacial Maximum. Roughly speaking, this is the most recent peak of the Ice Age, when the glaciers that covered large areas of the Northern Hemisphere reached their peak for the last time.

The detailed analyzes carried out with the objects are described in an article recently published in the British specialized magazine Proceedings of the Royal Society B. The work is signed by paleontologists Mírian Pacheco and Thaís Pansani, from UFSCar (Federal University of São Carlos), and by Águeda Vialou and Denis Vialou, from the National Museum of Natural History in Paris, among other researchers.

At the Santa Elina site, the researchers found thousands of osteoderms (bone structures in the dermis, one of the layers of the skin) from a species of giant sloth, the Glossotherium phoenesis, which reached more or less the size of a current ox. The structures, which do not appear in today’s sloths, are similar to the plates that cover armadillos (members of the same group that sloths are part of). Its function is still not well known, but it may be related to regulating the body’s temperature, says Pansani.

Three of the osteoderms discovered at the site are modified in such a way as to suggest human intervention. “At first glance, they have a shape that is very suggestive of pendants, mainly due to the polishing, which in some cases even changes the shape of the osteoderm, and the location of holes in them”, explained Pacheco to Sheet. The holes indicated that the bones could have been intentionally drilled and placed on a string, for example.

In the new study, the team used a series of methods of analyzing the microscopic structure of the artifacts, including with the help of particle accelerators in France, to map how these modifications occurred in osteoderms. The main conclusion is that they were carefully crafted with the help of stone artifacts (several of which have been found in Santa Elina).

“We also found evidence of the use of these artifacts as possible adornments, such as marks that suggest constant contact between the artifacts and surfaces —perhaps the users’ skin”, says the paleontologist. To validate these data, the team carried out experiments with other ancient osteoderms from the archaeological site and with osteoderms from current armadillos, showing that the polished appearance of the artifacts could, in fact, be produced by human action.

Furthermore, the pattern of changes in the bones indicates that they were modified relatively soon after the sloths died, not when they had already fossilized. It is, therefore, a clue in favor of the idea that humans who lived in the vicinity of the site coexisted with the giant mammal species and may have killed those sloths.

This data is important because, although it is clear that Brazilians from the Ice Age arrived in the country when the species of the so-called megafauna were still around, for the time being, evidence that they hunted these animals is very rare.

Several factors could explain this, according to Pacheco. “The first is weathering: the fact that it’s a tropical region, the humidity and the vegetation, all of this can jeopardize the preservation of the bones. Those of the giant sloths of Santa Elina, for example, are very friable [quebradiços]. They even crumble with handling. The osteoderms must have been preserved because they are more resistant”, she ponders.

Furthermore, the relative lack of researchers in the area in Brazil, as well as the complexity of the analyzes needed to prove something like hunting and consumption by human beings, could be part of the explanation for the relative lack of confirmed cases.

Pansani says he considers the very ancient dates of the archaeological site to be reliable. In that case, the simple coexistence of humans with giant sloths and other members of the Ice Age megafauna would not be a sign that the homo sapiens quickly exterminated them, since several of these species only disappeared for good in Brazil around 10,000 years ago.

The study was supported by Capes (Coordination for the Improvement of Higher Education Personnel), a federal government agency.