Author's note: The interpretation of the figures in the mural is not entirely settled. The interpretation used in this post is the one most I have found most often.
San Bartolo (in Guatemala's Department of Petén) is a site that contains the oldest known Maya murals, located in a small building in the eastern complex (called the Pinturas Group) of the site. Discovered about ten years ago, in 2002, the murals -- which have an Olmec influence -- are still something of a mystery.
The murals at the site of San Bartolo are believed to date from around 100 BC to 50 BC. This makes them about eight to nine hundred years older than the murals at Bonampak.
William Saturno, the official discoverer of San Bartolo, found the murals by accident. While searching for a shady place to rest in, he happened to see part of the murals, which were initially covered in rubble.
The North Wall
The left side of the north wall shows five babies coming out of a gourd. Archaeologists think this could be related to the origin myth of the cardinal directions. On the right side of the north wall is a woman offering tamales in a vase to Flower Mountain. To the right of the woman, eight figures ride a feathered serpent -- who they are is also a matter of speculation.
The West Wall
On the west wall is a mural about 98.4 feet long. This mural focuses on the maize god, who occurs seven times in it. Figures that may be his son, or perhaps many sons, perform such actions as: giving offerings of flowers as well as fish, turkeys and deer; setting up the world trees (a bird is in each one) in the cardinal directions; and giving their blood.
Another scene on this wall is the maize god on a wooden platform, which is thought to be a scene of his accession. Similarly, also depicted on the west wall is a scene -- with a painted text next to it -- of man receiving a headdress --, and this has been interpreted as an inaugural scene.
The text next to the inauguration scene is still something of a mystery to archaeologists. One glyph is understood though: an "ahau" (or "ajaw") glyph, a glyph that is usually translated as lord/king/ruler.
Archaeologists think this mural provides evidence that the divine king concept had already begun, at least in the lowlands, in the Preclassic period.
"The Ancient Maya"; Robert J. Sharer, Loa P. Traxler; 2006
"Maya Calendar Origins: Monuments, Mythistory, and the Materialization of Time"; Prudence M. Rice; 2007
"Oldest Mayan Mural Found by Peabody Researcher: Jungle Ordeal Leads to Surprise Treasure"; Alvin Powell; March 21, 2002