Meeting Abstract
Deciduous tooth morphology in mammals has received little attention despite the potential for insight into the ecology and phylogeny of these animals. We investigated the evolution of milk-tooth morphology in carnivorans with two goals: (1) document and quantify ecomorphological variation in deciduous dentition; and (2) assess the morphological integration of deciduous and permanent teeth at macroevolutionary scales. We collected ecomorphological data on milk and adult teeth of 44 extant species from eight families and conducted principal component analysis to identify major variations in the shapes and relative sizes of lower carnassial teeth (dp4/m1) and pre-carnassial premolars (dp3/p4), which are tied to dietary differences in adults. We then conducted phylogenetic regression analyses and fit models of trait evolution to the parallel data sets. Results show complex patterns of morphological variation and integration that depend on the phylogenetic scale. Across the families examined, the basic functional attributes of milk teeth and their adult counterparts are significantly correlated. For example, in canids both milk and adult teeth are conservative compared to other families. Mismatches are observed in some dentally specialized groups: felids and hyaenids have proportionally larger grinding areas in their milk teeth, and ursids have greatly reduced milk teeth. At finer phylogenetic scales (e.g., within families), the correlation between milk- and adult-tooth shapes is generally poor. The limited morphological integration of deciduous and permanent teeth is largely attributed to faster rates of evolution in adult teeth. The limited variation in the shapes of deciduous carnassial teeth may reflect developmental constraint or a homogeneous process of selection in juvenile ecology.
