Meeting Abstract

P2.67  Wednesday, Jan. 5  the relationship between relative jaw size and shape and tooth size in selenodont artiodactyls DAVIS, J.S.*; WILLIAMS, S.H.; Ohio University; Ohio University Jillian.S.Davis.1@ohio.edu

In selenodont artiodactyls, differences in relative jaw size and shape and tooth size have been related to mastication and diet. Relative jaw size and shape is thought to reflect resistance to specific loads that occur during repetitive mastication. For example, a relatively wider mandibular corpus in some species is thought to provide increased resistance to transverse bending during chewing. In contrast, relative tooth size is thought to reflect the physical properties of selenodont artiodactyl diets. In particular, hypsodonty is often interpreted as conferring more resistance to endogenous and exogenous dietary abrasives. In light of recent in vivo data drawing into question the adaptive significance of biomechanical interpretations of mandibular form in selenodont artiodactyls, we test the alternative hypothesis that jaw size and shape is influenced by overall tooth size. We test whether linear measurements of the jaws and teeth in a subset of grazing and browsing selenodont artiodactyls are significantly correlated. We also determine correlations between crown and root size and mandibular corpus cross sectional geometry, cortical area, and lingual and labial cortical bone thickness measured from CT scans. Results show that tooth size is not correlated with jaw size or biomechanically-relevant indices of cross-sectional geometry in selenodont artiodactyls. Also, relative size and shape of the mandibular corpus does not differ with diet. Within individuals, cortical bone thickness varies throughout the corpus, but the pattern of variation is similar across individuals regardless of diet. Combined, these results do not support a causal relationship between tooth and jaw size in selenodont artiodactyls. Supported by NSF.