Meeting Abstract

61.3  Saturday, Jan. 5  In vivo cranial bone strain during feeding in the agamid Uromastyx geyri PORRO, L.B.*; IRIARTE-DIAZ, J.; O’REILLY, J.; ROSS, C.F.; University of Chicago, IL; University of Chicago, IL; University of Chicago, IL; University of Chicago, IL lbporro@gmail.com

Due to its specialized skull and dental morphology, the herbivorous lizard Uromastyx has been the subject of numerous feeding studies. Previous research has collected data on cranial, mandibular and tongue kinematics, jaw and tongue muscle activity, and bite force generated under stimulation. Additionally, the computer modeling techniques of multibody dynamics analysis and finite element analysis have been applied to the skull of Uromastyx, allowing researchers to test hypotheses regarding the link between bone/suture morphology and mechanical behavior. To date, no data have been collected on bone strain in the skull of any herbivorous lizard, including Uromastyx. Bone strain data provide the most direct evidence of deformation, stress, and strain regimes in the skull under loads. We collected in vivo bone strain data from the crania of three Uromastyx geyri (along with simultaneously recorded electromyographic, videofluoroscopic and bite force data) during feeding on a variety of foods and while exhibiting different feeding behaviors (capture, chew, swallow, etc.). Analysis of principal and shear strains over 1300 individual gape cycles reveal that principal strain orientations vary little between individual animals, or with changes in food type and bite point; instead, variability in both principal strain orientations and magnitudes is primarily determined by feeding behavior. Furthermore, cranial bone strain magnitudes recorded in Uromastyx during feeding are substantially higher than those recorded in mammalian crania. These results shed new understanding on cranial biomechanics in Uromastyx during feeding and will be used to validate and improve the accuracy of previous computer models.