Importance of being organized: the effects of changing tooth arrangement on durophagous predation

Abstract

The literature on paleontology and functional morphology both include many studies on the feeding mechanics of organisms. In extinct organisms, physiological data must be inferred from bone structure, or muscles scars, even in the most exceptionally preserved specimens (Benton, 2010). However even reconstruction and analysis of muscle scars in fossils rely heavily on assumptions (Rieppel, 2002). Given the resilient nature of enamel, teeth are often the most commonly found remains of extinct organisms, and in some cases they are only known remains (Adnet et al., 2009; Pol, 2012). Enamel is highly calcified and so, unlike other softer portions of an organism’s anatomy, is readily preserved (Lucas et al., 2008). Fortunately, there is a close relationship between tooth form and function, which allows researchers to infer the ecology of the extinct organisms. Slender, pointed teeth, are ideal for puncturing, and bladed teeth are best suited for tearing and cutting prey, whereas more rounded and blunt teeth are thought to function better in crushing prey (Massare, 1987), a feeding strategy termed durophagy. Durophagous predators typically have robust jaw bones in addition to their distinctive and molariform teeth on the premaxilla, maxilla, dentary or the pharyngeal (Norton, 1988, Wilga and Motta, 2000). It is thought that this molariform tooth morphology, as well as tooth arrangement, may serve to increase tooth surface area, thus reducing the stress applied to teeth (Ramsay and Wilga, 2007) when crushing. Studies on the functional ability and structure of durophagous teeth have focused on a range of both extinct and extant organisms, including borophagines canids, early hominoids, and elasmobranchs (Lee et al., 2011; Lucas et al., 2008; Tseng ZJ and Wang X, 2010). For these groups, tooth form dictates diet and, by extension, habitat selection and population ecology. From there it is possible to study large-scale evolutionary patterns, co-evolutions, and trophic interactions (Lauten 2013).