DURHAM, N.H. (AP) – A University of New Hampshire professor’s excavation of Maya ruins in Guatemala continues to rewrite history.

Archaeologist William Saturno has revealed that a Mayan writing system was in use centuries earlier than previously thought.

The finding is detailed in the latest issue of the journal Science. Shortly after Saturno discovered the site, known as San Bartolo, in 2001 its vividly painted mural was heralded as the “Sistine Chapel” of the pre-Classic Maya world. The site contains a pyramid complex and several buried rooms.

The sample of Maya hieroglyphic writing dates from 400 B.C. to 200 A.D. It was located by Saturno and his team on preserved painted walls and plaster fragments buried in the structure.