Giant Armadillo Provides Evidence of Humans in S. America 20,000-Years-Ago

A new study reveals that ancient humans may have butchered and consumed a giant armadillo-like creature around 20,000 years ago in present-day Argentina. This discovery is another in a long line of emerging evidence that suggests that humans spread throughout the Americas much earlier than previously thought.

The study details the discovery of cut marks on fossil remains of a glyptodont called Neosclerocalyptus, an extinct giant armadillo relative. These bones, found in the Pampean region of Argentina, represent one of the earliest known instances of human interaction with megafauna in South America.

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Find location on the bank of the Reconquista River, in the town of Merlo, province of Buenos Aires. (UNLP)

Giant armadillos were covered in a protective shell made up of bony plates called osteoderms, resembling a turtle's carapace. Unlike their contemporary counterparts, glyptodonts were much larger, with some species reaching the size of a small car. Neosclerocalyptus had a robust build with a distinctive armored tail that could be used for defense against predators. These herbivorous mammals thrived in a variety of environments, from grasslands to woodlands, until their extinction around 10,000 years ago.

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3D digital reproduction of humans butchering a glyptodonts. (Damian Voglino, Museo de Ciencias Naturales/UNLP)

Massive Animals, Butchering Sequence: Understanding our Ancestors

Published in the journal PLOS One, the study has worked with an incomplete skeleton, found along the banks of the Reconquista River near Buenos Aires. It included parts of the pelvis, tail, and a portion of the carapace — the bony plates covering the animal's back. Carbon dating of a pelvic bone fragment placed the age between 21,090 and 20,811 years ago, aligning with the geological age of the surrounding sediment.

Giant armadillo bones, some of which show signs of butchery. (UNLP)

To ascertain if the cut marks were human-made, researchers photographed and created 3D scans of the bones. Several marks displayed a V-shaped cross-section, indicative of stone tool butchering. In total, 32 cut marks were identified on the bones. Statistical analysis confirmed that the marks were deliberate, made by humans using tools.

“These animals are closely related to the still-living armadillos,” said study coauthor Miguel Delgado, a researcher at the National University of La Plata in Buenos Aires, to CNN.

“The specimen we found belongs to one of the smallest species (of an extinct type of armadillo called Neosclerocalyptus),” Delgado said, noting its weight was about 300 kilograms (660 pounds) and its length 180 centimeters (almost 6 feet), including the tail. The animals are known for their armored scales and ability to roll up into a ball when threatened.

Reconstruction of the 3D scanned skeletal elements found and the carapace of the CRS-10 specimen in anatomical position. (Del Papa et al./PLoS ONE)

The researchers ruled out other potential causes for the marks, such as carnivore tooth marks, which are typically U-shaped, and natural weathering, since the animal's body was likely buried soon after death, protecting it from environmental degradation and scavengers.

The cut marks' locations suggest a butchering sequence, indicating that ancient humans likely harvested a significant amount of meat from the pelvis and tail muscles of the giant armadillo. “The cut marks were not randomly distributed but focused on those skeletal elements that harbored large muscle packs like the pelvis and the tail,” added Delgado in a press release.

Timeline of Arrival: Humans in the Americas

During the Late Pleistocene epoch (129,000 to 11,700 years ago), the Earth was covered in ice sheets and glaciers, especially during the Last Glacial Maximum, approximately 26,000 to 20,000 years ago, when the ice age was at its peak. Initially, archaeologists believed that the first Americans arrived by crossing a land bridge from Siberia to Alaska about 13,000 years ago. However, recent archaeological sites in North and South America indicate that humans may have arrived much earlier.

Along with three perforated giant sloth bones found in Brazil last year, which archaeologists believe humans used as pendants 25,000 to 27,000 years ago, the butchered armadillo bones suggest that humans were in South America a surprisingly long time ago. These findings indicate that human presence in the region dates back much further than previously assumed, reshaping our understanding of early human migration and interaction with megafauna on the continent.

This study not only highlights early human-megafauna interactions but also "pushes back the chronological frame of both human presence and human-megafauna interactions nearly 6,000 years earlier than recorded for other sites in southern South America," the authors stated.

While the researchers acknowledge the need to strengthen the connection between fossil bones with cut marks and the archaeological record, they are hopeful that future studies will establish this link, reports Live Science.

“Until recently, the traditional model indicated that humans entered the continent 16,000 calendar years ago. Our results, in conjunction with other evidence, proposes a distinct scenario for the first human peopling of the American continent, that is, the most likely date for the first human entry occurred between 21,000 and 25,000 years ago or even before,” concludes Delgado.

Top image: 3D digital reproduction of humans butchering a glyptodonts.          Source: Damian Voglino, Museo de Ciencias Naturales/UNLP

By Sahir Pandey