Meeting Abstract

61.4  Saturday, Jan. 5  Cranial bone strain in the teiid lizard Tupinambis merianae and the diversity of optimality criteria in vertebrate skulls ROSS, C.F.*; HERREL, A.; PORRO, L.B.; EVANS, S.E.; FAGAN, M.J.; MURRAY, K.D.; University of Chicago; C.N.R.S/M.N.H.N. ; University of Chicago; University College London; University of Hull; University of Chicago rossc@uchicago.edu

In vivo bone strain data provide the most direct evidence of patterns of strain in the skull during feeding and have provided important insights into skull design in mammals and Alligator. These data suggest that bone strain magnitudes in the calvaria and upper face of mammals are absolutely low, and low compared with strain magnitudes elsewhere in the skull. This suggests that the calvaria and upper face are not optimized for resisting feeding forces—where optimality is defined as maximum strength with minimum material—because they are optimized for other functions, including protection of the brain and eyes. Here we present in vivo bone strain data recorded from the cranium of the teiid lizard, Tupinambis merianae during transducer biting and feeding. Tupinambis experiences very high strain magnitudes in the frontal and parietal bones during feeding, much higher than those recorded at comparable sites in mammals. These results suggest that the cranium of Tupinambis, like those of Alligator and Sphenodon, is more optimized for resisting feeding forces than is the cranium of mammals. During feeding the snout of Tupinambis is bent, sheared and twisted, depending on bite point and behavior, emphasizing the importance of recording strain data across a wide range of natural behaviors. In contrast, the deformation regime in the parietal bone is relatively constant across behaviors. This suggests that the “mesokinetic hinge” between frontal and parietal bones absorbs strain energy associated with forces acting on the snout of Tupinambis during feeding.