AMARILLO (CBSDFW.COM) – Construction workers excavating the site of a new facility at the Pantex Plant recently turned up something unexpected: a prehistoric pig.

The Amarillo Globe-News reported that the workers found the bones last week about 8 feet down in the walls of their excavation

Dr. Gerald Schultz, a geology professor at West Texas A&M University in nearby Canyon, identified the bones as belonging to a Platygonus, an extinct prehistoric pig related to a modern javelina. The professor says Platygonus became extinct at least 11,000 years ago, but the bones could be as old as 23 million years old.

Monica Graham, the Pantex Plant’s historian, worked with a wildlife biologist and a geologist to excavate the bones

The plant near Amarillo is the nation’s only nuclear weapons assembly and disassembly facility.