Popol Vuh
The Jaguar Twin Hero, companion to Hun-Ahpu (or Hun-Ajaw) and thus corresponding to Xbalanque in the much later Popol Vuh Twin myth, has patches of jaguar skin stuck to his arms and body, in addition to jaguar pimples around his mouth. Fittingly, in the Popol Vuh, Xbalanque is the more violent Twin.