Mandible Shape in Marsupial and Placental Carnivorous Mammals: Morphological Comparative Study using Geometric Morphometry

TURAZZINI, GUILLERMO FIDEL; ERCOLI, MARCOS DARÍO; PREVOSTI, FRANCISCO JUAN

Mendoza

Congreso; 10th International Mammalogical Congress; 2009

GIB - IADIZA; CCT; CONICET; IFM y SAREM

Several authors had studied skull and mandible shape in carnivorous mammals showing the convergence between different marsupials and eutherians (i.e. Carnivora). In this work we analyzed the mandible shape using 2D geometric morphometry. Using this method we explored the relationship between shape, size and phylogeny. We analyzed almost 560 specimens, covering most of the genera of the terrestrial Carnivora and a wide sample of marsupials. We used 29 landmarks and semilandmarks to describe the mandible in a lateral view. The observed shape variation had ecological and phylogenetic components. For example, omnivorous species had low scores on the second PCA axis, with strong mandibles and large talonid in the carnassials, while hypercarnivores were concentrated with high scores on the PCA axes 1 and 2, having short mandibles and reduced talonids. On the other hand, most of the Carnivora families formed clusters indicating some kind of phylogenetic constraint. Marsupials overlapped with hypercarnivore and mesocarnivore plancentals, especially of the Canidae and Felidae families, and presented less variation than Carnivora. There is a significant variation due to the allometry factor, however this factor explained less than 5% of total variation, where the largest species had shorter and stronger mandibles, with anteriorly displaced carnassials.