On Monument 24 (Altar P') from Quirigua "the god Chac [the rain god] appears bursting into the sky from a great crevice, accompanied by wild scrolls of blood, k'uhul, and vision serpents. Metamorphosing from these scrolls are the semiskeletal heads of two reptilian zoomorphs with upturned snouts, one of which wears some kind of extension on the tip of its muzzle."
Elizabeth A. Newsome, Trees of Paradise and Pillars of the World: The Serial Stela Cycle of 18-Rabbit-God K, King of Copan, p. 146
NOTE: Chac's feet appear in the "V" in the center of the "T" shaped inscription. His head is in the center forground of the photo, with arms extended to either side of the head, grasing a two-headed serpent that may represent the double-headed ceremonial bar.