BAGANA, M; DANOS, N; University of San Diego; mbagana@sandiego.edu Sexual dimorphism in chameleon feeding. Sexual dimorphism of skull anatomy is prevalent among chameleons. Male Jackson’s chameleon, Trioceros jacksonii, have three cranial bony horns. However, these horns are not present in females. Given the highly specialized feeding mode of chameleons, we wanted to know whether this large cranial skeletal feature incurred a cost on male feeding performance. We filmed 14 male and 16 female animals at 250 frames per second from ventral and lateral views as they fed on a stationary held cricket, and quantified three-dimensional tongue kinematics. We found no sexual dimorphism in tongue projection kinematics, suggesting that there is little or no fitness cost associated with the large horns of the male T. jacksonii. Preliminary data from Chamaeleo calyptratus had suggested that females have a relatively larger entoglossal process of the hyoid. However, this did not hold true for a much larger sample of T. jacksonii (N=59 and N=103 for females and males, respectively). In fact, we found no evidence of sexual dimorphism in cranial morphology other than the presence or absence of horns. The absence of sexual dimorphism is highly unusual for chameleons. We explored whether there were changes in the ecology of the species from high altitudes in East Africa to lower altitudes after their introduction to Hawaii.