Excavations at the Maya site of San Bartolo, in Petén, Guatemala, have uncovered fragments of a mural that may represent the earliest evidence of the Maya ritual calendar ever found.
The fragments were unearthed during archaeological investigations of the site’s most significant feature: a large pyramid, which was rebuilt seven times between 400 BC and AD 100. The pyramid was named Las Pinturas (‘the paintings’) after the 2001 discovery of a room filled with colourful murals dating to its penultimate phase (c.100 BC). However, the newly identified calendar mural fragments date to the pyramid’s third phase (c.300 to 200 BC), known as the Sub-V complex, which consisted of a radial pyramid, a ballcourt, and a long, raised platform. In the fill material used to cover these structures as part of the construction of a new pyramid 50-100 years later, archaeologists uncovered hundreds of fragments of painted plaster that once covered the walls of the Sub-V complex.
Of the 249 fragments discovered, 11 are decorated with glyphic images, and the most significant of these are two mural pieces that represent a date from the Maya calendar. The two small fragments fit together to depict the Maya number seven – two dots over a horizontal line (although the section with the left dot is missing here) – above the head of a deer. ‘7 Deer’ was a date in the Maya 260-day ritual calendar, which used different combinations of 13 numbers and 20 signs to represent distinct dates.
Only a few other examples of these 260-day calendar date records are known from the Late Preclassic period, and most are found on stone monuments that are very difficult to date with any precision. The sealed context in which the San Bartolo fragments were found, which has been radiocarbon dated to 300-200 BC, provides a uniquely secure date for this depiction and makes it among the earliest, if not the earliest, evidence of the 260-day calendar currently known.
This discovery demonstrates that this calendar system, which is still used by some indigenous communities across Mesoamerica today, has been in operation for at least 2,200 years, and – given the complexity of the depiction – probably for several centuries before this.
The research has now been published in Science Advances (https://doi.org/10.1126/sciadv.abl9290).