EVANS, A.R.*; WILSON, G.P.; JERNVALL, J.; FORTELIUS, M.; Inst. of Biotechnology, Univ. of Helsinki, Finland; Denver Museum of Natural History, Colorado; Inst. of Biotechnology, Univ. of Helsinki, Finland; Dept. of Geology and Inst. of Biotechnology, Univ. of Helsinki, Finland: New methods in 3D tooth shape analysis: a study of form and function in murine and sigmodontine rodents

The correlation between the dentition and the diet in mammals is a perennial topic of research, due to the importance of the teeth in food processing and their preponderance in the fossil record. However, most often very simple aspects of morphology, such as lengths and widths of teeth or crests, have been used to draw a parallel with ecological and dietary information. The explosion of methods for capturing 3-D surface data on morphology has opened the door to a new range of possibilities in analysis. These are not limited to using two-dimensional representations of teeth and can exploit the full 3-D tooth shape, including true surface areas, volumes and curvatures. In addition, we are now capable of tooth shape analyses that do not require identification of homologous landmarks. Here, we present a new techniques that uses general characteristics of shape to give summary information on aspects that can be related to some functional measures. We demonstrate the application of these techniques in exploring the evolution of dietary groups in two separate radiations of murid rodents, the murines and the sigmodontines. These rodents are very diverse in ecology and diet, ranging from strict herbivores, granivores or faunivores, to having broad diets. Certain general measures of shape, such as �complexity� (measured as number of distinct faces) and orientation of tooth surfaces, correlate well with diet. The power of these new techniques is displayed in the ability to analyse diverse morphologies in using the same methodologies, not being limited to homological comparisons.