"A headdress composed of a giant coil of spotted material--snakeskin or a roll of stuffed jaguar pelt--was invented during the reign of Bird Jaguar IV. It is worn with a standard set of accessories: a bead headband, the "bell element," a stuffed jaguar tail, a jester god, the serpent-wing element, muan bird feathers, and the GI-Chac Xib Chac diadem."
Carolyn E. Tate, Yaxchilan: The Design of a Maya Ceremonial City, p. 74-5
NOTE: The sphere underneath Bird Jaguar's nose could be a nose ornament, but more probably it represents vital breath or life force. Such elements can also be seen in the monumental masks at Kohunlich.