Abstract

Developmental origins that guide the evolution of dental morphology and dental formulae are fundamental subjects in mammalian evolution. In a previous study, a developmental model termed the inhibitory cascade model was established. This model could explain variations in relative molar sizes and loss of the lower third molars, which sometimes reflect diet, in murine rodents and other mammals. Here, I investigated the pattern of relative molar sizes (inhibitory cascade pattern) in canids, a taxon exhibiting a wide range of dietary habits. I found that interspecific variation in canid molars suggests a unique inhibitory cascade pattern that differs from that in murine rodents and other previously reported mammals, and that this variation reflects dietary habits. This unique variability in molars was also observed in individual variation in canid species. According to these observations, canid species have greater variability in the relative sizes of first molars (carnassials), which are functionally important for dietary adaptation in the Carnivora. In conclusion, an inhibitory cascade that differs from that in murine rodents and other mammals may have contributed to diverse dietary patterns and to their parallel evolution in canids.

Highlights

  • Dental morphology and dental formulae are important taxonomic traits in mammals (Ungar 2010), and are used for paleoecological and ecomorphological studies in mammals because these traits reflect dietary adaptations (Popowics 2003; Benton 2004; Friscia et al 2007; Van Valkenburgh 2007)

  • These results are in agreement with the consensus area of the inhibitory cascade model suggested by Polly (2007)

  • Interspecific variation in relative molar sizes among the majority of canid species, excluding Otocyon megalotis, exhibited a pattern that differed in slope from the variation observed in murine rodents (Kavanagh et al 2007)

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Summary

Introduction

Dental morphology and dental formulae are important taxonomic traits in mammals (Ungar 2010), and are used for paleoecological and ecomorphological studies in mammals because these traits reflect dietary adaptations (Popowics 2003; Benton 2004; Friscia et al 2007; Van Valkenburgh 2007). Developmental mechanisms that guide and constrain patterns of adaptation in dental morphology and dental formulae are crucial subjects for elucidating their proximate and ultimate factors, and the interactions between these factors during dental evolution (Kavanagh et al 2007; Laland et al 2011; Wilson 2011). Many recent studies have focused on the developmental mechanism of the evolution of dental morphology and dental formulae, which guide and constrain the reflection of dietary adaptations A recent developmental study established a developmental model that can explain evolution of the relative sizes of lower molars in murine rodents (Kavanagh et al 2007).

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