“The Olmec were-jaguar is the name for both an Olmec motif and an Olmec supernatural.

The were-jaguar motif is charactertised by almond-shaped eyes, a downturned open mouth, and a cleft head. It appears widely in the Olmec archaeological record, and in many cases, under the principle of pars pro toto, the were-jaguar motif represents the were-jaguar supernatural. The were-jaguar supernatural incorporates the were-jaguar motif as well as other features, although various academics define the were-jaguar supernatural differently. The were-jaguar supernatural was once considered to be the primary deity of the Olmec culture but is now thought to be only one of many.”

http://en.wikipedia.org/wiki/Olmec_were-jaguar