After almost ten months of excavations, INAH team has recovered 824 woolly mammoth bones in Tultepec. Photo: Edith Camacho, INAH.

By Brigit Katz. First published on Smithsonian.com

In the neighborhood of Tultepec, just north of Mexico City, plans were recently underway to convert a patch of land into a garbage dump. But during preparatory excavations, workers at the site found themselves digging up woolly mammoth bones—hundreds of them. Over the course of ten months of archaeological and anthropological work, experts were able to piece together a grim picture of what appears to have been a prehistoric hunting site. The team had, according to the Associated Press, stumbled upon two large man-made traps—pits where hunters drove woolly mammoths to their deaths.

Researchers with Mexico's National Institute of Anthropology and History (INAH) announced the discovery this week, saying that it lends “unprecedented context” to experts’ understanding of how ancient humans hunted woolly mammoths. The pits date to 15,000 years ago, each measuring 5.5 feet deep and 82 feet long, reports CNN's Jack Guy. Inside the pits were 824 mammoth bones, among them eight skulls, five jaws, a hundred vertebrae and 179 ribs. Experts say the remains correspond to at least 14 individual mammoths. Bones belonging to a camel and a horse were also found.

According to INAH researchers, the pits may have been vital tools for ensnaring a formidable prey; woolly mammoths, which went extinct some 4,000 years ago, could stand more than 11 feet tall and weigh up to eight tons. Experts think that groups of hunters, perhaps numbering between 20 and 30 people, would separate one individual from the herd and drive it towards the pits, possibly frightening it with torches and branches. Once inside the trap, the animal would be killed.

Some of the remains bore signs of butchering. Marks on the remains suggest, in fact, that mammoth rib bones were used to cut away the meat. Another bone found at the site seems to have been deployed as a polishing tool, possibly for stripping fat from skin. Skulls were flipped upside down, likely because ancient hunters would eat the mammoths’ tongues.

After almost ten months of excavations, INAH team has recovered 824 woolly mammoth bones in Tultepec. Photo: Edith Camacho, INAH. The discovery offers the probability of “evidence of direct attacks on mammoths”.

Other “megasites” where humans processed mammoth carcasses in large numbers have surfaced in Eurasia and North America, Adam N. Rountrey, a collection manager at the University of Michigan Museum of Paleontology, explains to Emily S. Rueb of the New York Times. But it hasn’t been clear whether humans were actively hunting the animals—perhaps with the help of dogs—or simply scavenging them after the animal died of natural causes. None of the previously known sites had been identified as man-made.

The Tultepec site, by contrast, offers “evidence of direct attacks on mammoths,” Luis Córdoba Barradas, the leader of the excavation, told reporters, according to the Guardian’s Jo Tuckman. Rountrey is more cautious, telling Rueb that experts “are looking forward to seeing a peer-reviewed publication that presents the evidence for human construction of the traps.”

Even Córdoba admits that much about the discovery remains mysterious. For instance, only right shoulder blades were found among the mammoth remains—what happened to the left ones, no one can say for certain. Perhaps, the INAH theorizes, a ritual element was at play, as seems to have been the case with other remains. According to CNN’s Guy, the bones of one mammoth were arranged in “symbolic formation,” and intriguingly, one of the bones showed signs of a healed fracture. Maybe the hunters had attempted to kill this animal multiple times, perhaps tracking it over the years.

"They must have considered it brave and ferocious,” Córdoba said, per Guy. And when they killed it, they “[showed] their respect with this particular arrangement."

Researchers think the newly unearthed pits may have been part of a chain of traps, a strategy that would have increased the hunters’ chances of snagging their prey. And this in turn means that additional traps—and the remains of whatever creatures they contain—could surface in the future.