Close to the small Mexican village of Onavas, south Sonora, archaeologists have uncovered the first pre-Hispanic cemetery of that area, dating to around 1,000 years ago.
© INAH
Juvenile burial with shell bracelet and earrings.
A unique burial ground
© INAH
Individual buried with a turtle shell placed over the abdomen.
The burial ground consists of 25 individuals; 13 have intentional cranial deformation and five also have dental mutilation, cultural practices which are similar to those of pre-Hispanic groups in southern Sinaloa and northern Nayarit, but until now, have not been seen in Sonora.

Some of the individuals were wearing ornaments such as as bangles, nose rings, earrings, pendants made from shells found in the Gulf of California, and one burial contained a turtle shell, carefully placed over the abdomen.

However, the archaeologists noted that the burials were not accompanied by the expected offerings and containers.

For archaeologists, the discovery is exciting new evidence of cranial deformation, something which has not been recorded before in the Sonora cultural groups.

"This unique find shows a mix of traditions from different groups of northern Mexico. The use of ornaments made from sea shells from the Gulf of California had never been found before in Sonoran territory and this discovery extends the limit of influence of Mesoamerican peoples farther north than has been previously recorded," said archaeologist Cristina Garcia Moreno, director of the research project.

Garcia Moreno has been conducting work on behalf of Arizona State University with approval of the National Institute of Anthropology and History (INAH).

© INAH
One of the 13 individuals with cranial deformation discovered in the cemetery.
Mutilation and deformation as a mark of status

The archaeologist said that, "Cranial deformation in Mesoamerican cultures was used to differentiate one social group from another and for ritual purposes, while the dental mutilation in cultures such as the Nayarit was seen as a rite of passage into adolescence. This is confirmed by the findings at the Sonora cemetery where the five bodies with dental mutilation are all over 12 years in age."

However, she continued,"In this case, you cannot recognise any social differences because all the burials seem to have the same characteristics. Nor have we been able to determine why some were wearing ornaments and others not, or why of the 25 skeletons only one was female. "

Of the skeletal remains of 25 individuals recovered, 17 are between 5 months and 16 years and 8 are adults. The researcher noted that the number of infants and pre-pubescents identified in the cemetery may be an indicator of poor practice in regards to cranial deformation and death likely was caused by excessive force while squeezing the skull. This she said, is derived from studies conducted on the remains and the results did not show any apparent diseases that could have caused death.

The importance of the discovery is the suggestion of influence of Mesoamerican societies in southern Sonora, much further north than previously thought. "Because of the characteristics of individuals who were found in Ónabas, especially from the deformation of the skull and teeth mutilation, they are related and connected societies in southern Mexico, for example, Michoacán, Nayarit, Jalisco , and in turn, with the Mesoamerican cultural zone."

The find has been dated to the year 943 CE from samples taken from one of the individuals. Garcia Moreno pointed out that Middle America had been affected by the arrival of settlers from the south, and this may have taken their influence further north than previously believed.

Video of the find ( in Spanish)