I’m not a fan of Von Daniken either, but this artifact needs a whole lot more investigation and research, it’s just so out of place imo.
"In reality, the relief shows the World Tree, which the Maya believed had its roots in the underworld, trunk on the earthly plane, and branches high in paradise, and Pacal's relationship to it in death. The king is depicted either at the moment of his death falling from the earthly plane down into Xibalba or at the moment of his resurrection from the underworld, climbing up the World Tree toward paradise. The adornments along the edges represent the sky and other glyphs the sun and moon and, still others, past rulers of Palenque and Pacal's place among them. The bird at the top of the tree is the Bird of Heaven (also known as The Celestial Bird or Principal Bird Deity) who represents the realm of the gods in this piece, and the `urn' beneath Pacal is the entrance to Xibalba." link