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More than 20,000 years ago, in what is now Argentina, some of the first humans in the Americas encountered and dismembered a giant armadillo-like creature with stone tools, according to a new study.
The discovery, extracted from cut marks in the fossilized remains of an ice age creature, adds to recent evidence that the Americas were settled much earlier than archaeologists first thought, perhaps more than 25,000 years ago.
“These animals are closely related to still-living armadillos,” said study co-author Miguel Delgado, a researcher at the National University of La Plata in Buenos Aires. The animals are known for their armored scales and ability to roll into a ball when threatened.
“The specimen we found belongs to one of the smallest species (an extinct armadillo species called Neosclerocalyptus),” Delgado said, noting that it weighed about 300 kilograms (660 pounds) and was 180 centimeters (about 6 feet) long, including its tail.
The fossilized vertebrae and pelvis of the animal, found on the banks of the Reconquista River near the city of Merlo in the Buenos Aires metropolitan area, were unearthed by a bulldozer.
Radiocarbon dates from bones and bivalve shells found in the same sediment layer revealed the armadillo remains to be between 20,811 and 21,090 years old, according to the study published Wednesday in the journal PLOS One.
The cuts weren’t immediately obvious, but cleaning the fossils revealed 32 linear tracks. After careful analysis, the team ruled out the tracks being made by rodents, carnivores that might have preyed on the animals, or other factors such as chewing, Delgado said.
Instead, the team determined that the pattern of the cut marks was consistent with those made with stone tools. According to Delgado, the placement of the marks suggested that the animals were butchered for meat, with a deliberate sequence of cuts focused on dense areas of the armadillo’s flesh.
“The cut marks were not randomly distributed, but instead were focused on skeletal elements housing large muscle packages, such as the pelvis and tail,” he said.
Paleoanthropologist Briana Pobiner, a research associate in the Human Origins Program at the Smithsonian National Museum of Natural History in Washington, D.C., said the authors present “compelling evidence” that humans massacred this extinct armadillo 21,000 years ago.
“The authors have done a solid job of demonstrating through qualitative and quantitative analyses that the cut marks on the armadillo fossils were most likely made by humans,” Pobiner, who was not involved in the study, said in an emailed statement.
First People in America
When and how humans first migrated from Africa to North and South America, the last places they spread across the world, has long been debated and poorly understood by experts.
Current estimates of the region’s first settlers range from 13,000 to 20,000 years ago, but the earliest archaeological evidence for the region’s settlement is scanty and often controversial.
The discovery of fossilized footprints imprinted in mud in New Mexico dating back 21,000 to 23,000 years, described in a September 2021 study, is the most definitive example in a string of recent evidence that the arrival of the first inhabitants was much earlier than many scientists thought.
At the time, the planet was in the grip of the Last Glacial Maximum, a period when two massive ice sheets covered the northern third of North America between 19,000 and 26,000 years ago, reaching as far south as what is now New York, Cincinnati and Des Moines, Iowa.
The cold temperatures brought by ice sheets and glaciers would have made travel between Asia and Alaska (the most likely route) impossible at the time, meaning the people who left the footprints likely arrived much earlier.
Along with three perforated giant sloth bones found in Brazil that archaeologists believe people used as necklaces 25,000 to 27,000 years ago, cut armadillo bones suggest that humans were in South America a surprisingly long time ago.
When humans first settled in the Americas, which at the time was home to many now-extinct ice age creatures, is a “hotly debated topic,” Delgado said.
“Until recently, the traditional model held that humans entered the continent 16,000 calendar years ago,” he said.
“Our findings, together with other evidence, suggest a distinct scenario for the first human settlement of the Americas; that is, the most likely date of the first human entry is 21,000 to 25,000 years ago or earlier.”
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