Meeting Abstract

S2.2  Tuesday, Jan. 4  Mammalian Masticatory Muscles: homology, nomenclature, and diversification DRUZINSKY, R.E.*; DOHERTY, A.H.; DE VREE, F; Univ. of Illinois, Chicago; Northeast. Ohio Univ. Col. of Med. and Pharm.; Univ. of Antwerp, Belgium druzinsk@uic.edu

There is a deep and rich literature of comparative studies of jaw muscles in mammals (e.g., Toldt,1905; Edgeworth, 1935; Turnbull, 1970) but no recent analyses employ modern phylogenetic techniques to better understand evolutionary changes that have occurred in these muscles. In order to fully develop and utilize the FEED database, we are constructing a comprehensive ontology of mammalian jaw muscles. This process has led to a careful consideration of nomenclature and homologies of the muscles and their constituent parts. Precise determinations of muscle attachments have shown that muscles with similar names are not necessarily homologous (Druzinsky, 1989; Hautier et al., 2008, 2010). Using new dissections and descriptions from the literature, we defined character states for the jaw muscles in diverse mammalian species. We then mapped those characters onto recent phylogenies of mammals (e.g., O’Leary et al., 2004; Prasad et al., 2008; Scally et al., 2002) with the aid of the Mesquite software package (Lim and Dunlop 2008; Maddison and Maddison, 2006). Our data further elucidate how muscle groups associated with the feeding apparatus differ and have become highly specialized in certain mammalian orders, such as Rodentia, while remaining conserved in other orders. We anticipate this study, in association with the FEED database, will generate new and significant comparative studies involving the functional, structural, and evolutionary morphology of the jaw muscles.