This carved and painted human mandible (jawbone) was found in a ceremonial area within a residential complex at the site of Dainzú-Macuilxóchitl in Mexico.

Painted human mandibles that may have been worn like necklace pendants have been discovered at a ceremonial site in Mexico that dates back around 1,300 years.

In the same ceremonial area, numerous whistles and figurines were also discovered. Made out of ceramic, these objects had been smashed into thousands of fragments, not a single example found intact.

The whistles may have made owl-like sounds, archaeologists said. Some of the figurines were sculpted images of Xipe Totec, a Mesoamerican god associated with human sacrifice and agricultural activity. The god was often shown with human bones draped around his neck. [In Photos: Human Sacrifices Unearthed in Mexico]

Discovered in the spring and early summer of 2015, the ceremonial site where the painted human jawbones were found is located within an ancient residential complex at the site of Dainzú-Macuilxóchitl in the Oaxaca Valley in southern Mexico. The site was used by the Zapotecs, a people who still live in the region and speak their own Zapotec language.

Jeremias Pink, a graduate student at Oregon State University, presented a poster discussing his team's discovery recently at the Society for American Archaeology annual meeting. The discovery is being prepared for publication.

Ancestor veneration?

While the god Xipe Totec is associated with human sacrifice, archaeologists said they think the painted bones came not from human sacrifices but rather from the ancestors of the people who lived in the residential complex.

When archaeologists excavated the complex, they found that it had been inhabited for at least 400 years. "We think that these residences were occupied by a series of families that were related to each other over those 400 years," said Pink, who led the excavation of the ceremonial area, in an interview with Live Science.

During the families' long period of habitation at the residential complex, the bones of the residents were exhumed, painted and modified, the archaeologists said. People were "probably going into the tombs of their ancestors and bringing the remains of their ancestors out," Pink said. People likely used the bones of their ancestors "in a ritual way to demonstrate the linkages between themselves and their ancestors as a way of sort of legitimizing their positions within that community," he said.

While modern-day Westerners may view this practice as being unusual, rituals involving ancestors were commonly practiced in ancient Mesoamerica, said Ronald Faulseit, a postdoctoral fellow at the Field Museum in Chicago, who directs excavations at Dainzú-Macuilxóchitl. That's true even today. For instance, on Nov. 2, modern-day Mexicans celebrate the "Day of the Dead," in which their ancestors are remembered (although the ancestors' bones are not dug up).

Smashing mystery

The archaeologists found roughly 3,000 figurine fragments and 1,600 whistle fragments. A ceramic kiln and about 30 figurine molds were also discovered in the ceremonial area, suggesting that at least some of the figurines and whistles were made in the ceremonial area.

While some of the figurines showed Xipe Totec, the identity of many of the fragments remains unknown. All of the figurines and whistles seem to have been intentionally smashed, a practice seen at other ancient Mesoamerican sites, Pink said.

"I would only be speculating" as to why they were smashed, Pink said. "There's this clear pattern of breaking them across the neck of the figurine," he added. Analysis of the figurines and other archaeological remains is ongoing, he said.

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