Caracterización morfólogica del M2 de primates Hominoidea a partir de análisis de Fourier

Résumé

Fourier analysis can allow to characterize the shape of teeth, by employing a number of landmarks defining its profile, and extract a number of parameters for subsequent multivariate analysis. However, the great complexity of some cases requires testing how many landmarks are needed for a correct representation. The aim of this paper is to apply and validate the Fourier analysis (Polar and Elliptic) in the dental conformation study by using different contour landmarks, and explore the morphometric variability in different genera. Digital photographs were obtained in occlusal view of second lower molars (M2s) of 4 species of primates (Hylobates moloch, Gorilla beringei graueri, Pongo pygmaeus pygmaeus and Pan troglodytes schweirfurthii). Teeth was defined with 30, 40, 60, 80, 100 and 120 landmarks, and 10 harmonics were obtained in each case. The variability was analyzed by applying Discriminant Analysis and NP-MANOVA from distance matrices to determine the percent of correct classification at methodological and taxonomical levels. The results shown that Fourieranalysis detect intergenus variability of shape in M2s of Hominoidea genera, regardless of the number of landmarks defining the contour. The classification rates presented higher variability in Polar (≈60-90) analysis than in Elliptic ones (75-100%). Using between 60-100 landmarks in an elliptic analysis ensures a good discrimination of tooth shapes in Hominoidea.