It was a jaw-dropping discovery.

A mouth prosthetic on a 2,500-year-old Siberian mummy could potentially be the earliest example of complex jaw surgery in history, per a groundbreaking study by researchers at Russia’s Novosibirsk State University (NSU).

“It is possible that we have discovered evidence of such a surgical procedure for the first time,” Dr. Andrey Letyagin, a Russian radiologist who helped conduct these fossil forensics, said in a translated statement.

The surgical saga dates back to 1994, when archaeologists with the Russian Academy of Sciences excavated a burial ground in the remote Ukok Plateau, uncovering the remains of the ancient patient in the permafrost, Livescience reported.

Estimated to be around 25 to 30 years old when she died, the woman was reportedly lying on a wooden bed and rocking a wig typical of the Pazyryk people — a nomadic horse-riding tribe that marauded about the Central Asian steppes between the sixth and third centuries BC.