Current Projects:
>	Ontogeny of chewing motor patterns and jaw-muscle coordination
>	Evolution of chewing motor patterns
>	Ecological physiology of feeding in howler monkeys
>	Masticatory biomechanics and jaw form in mammals
	Ongoing research in my lab seeks to describe and interpret loads incurred along the jaw during mastication and other behaviors and relate these loading patterns to jaw-muscle activity, jaw morphology and cross-sectional geometry. Loading patterns are determined using strain gauges attached to the bone. The ultimate goal of these studies is to understand the role that masticatory loading plays on shaping the evolution of jaw morphology in mammals. Special emphasis is on the evolution of mandibular symphyseal fusion in ungulates, notably alpacas and horses, and the correlation between symphyseal loading patterns, jaw-muscle activity and symphyseal fusion. Alternative hypotheses for the evolution of jaw morphology are also investigated in these studies, including the role that the mandible plays in housing the teeth. This may be particularly relevant for species that have hypsodont (high-crowned) teeth or who have a prolonged period of tooth development and crown formation in the jaw, as in most artiodactyls and perissodactyls. Collaborators and Students: JoAnna Sidote (OUCOM), Chris Vinyard (NEOUCOM), Christine Wall (Duke Univ.), William Hylander (Duke Univ.), and Jillian Davis (PhD Student in OU-EEB). Funded by the National Science Foundation.
>	Adaptations for gape and bite force production in rodents
>	Morphology of the feeding apparatus in vampire bats

       

Ravosa MJ, CF Ross, DB Costley, SH Williams, SW Herring, Zi-Jun Liu, KL Rafferty, WL Hylander. In review. Allometry of masticatory loading patterns in mammals. Anatomical Record.

Williams S, CJ Vinyard, CE Wall, WL Hylander. 2009. Mandibular corpus bone strain in goats and alpacas: Implications for understanding the biomechanics of mandibular form in selenodont artiodactyls. Journal of Anatomy, 214: 65-78.

Williams, SH, CE Wall, CJ Vinyard, and WL Hylander. 2008. Symphyseal fusion in selenodont artiodactyls: new insights from in vivo and comparative data. In Vinyard C.J., Ravosa M.J. and C.E. Wall (eds.) Primate Craniofacial Function and Biology. Springer: New York, p. 39-61.

Ross CF, A Eckhardt, A Herrel, WL Hylander, KA Metzger, V Schaerlaeken, RL  Washington, and SH Williams. 2007. Modulation of intra-oral processing in mammals and lepidosaurs. Integrative and Comparative Biology 47:118-136.

Ross, CF, R Dharia, SW Herring, WL Hylander, ZJ Liu, KL Rafferty, MJ Ravosa, SH Williams. 2007. Modulation of mandibular loading and bite force in mammals during mastication. Journal of Experimental Biology 210: 1046-1063.

Vinyard, CJ, CE Wall, SH Williams and WL Hylander. 2003. A comparative functional analysis of skull morphology of tree-gouging primates. American Journal of Physical Anthropology 120:153-170.

Williams, SH, CE Wall, CJ Vinyard and WL Hylander. 2002. A biomechanical analysis of skull form in gum-harvesting galagids. Folia Primatologica 73:197-209.

Williams, SH and RF Kay. 2001. A comparative test of adaptive explanations for hypsodonty in ungulates and rodents. Journal of Mammalian Evolution 8:207-229.