Evolution of jaw shape and biomechanics in carnivores: a phylogenetic approach

DE ESTEBAN-TRIVIGNO, SOLEDAD; MARCÉ-NOGUÉ, JORDI; BOSCAINI, ALBERTO; CANTALAPIEDRA, J.

Haarlem

Congreso; XIV Meeting of the European Association of Vertebrate Palaeontologists; 2016

Carnivorans are a highly diversified group that shows adaptations to many different ecological niches. Despite the relationship between jaw shape and biomechanics has been thoroughly studied in the past, no study has analysed both characteristics in an evolutionary framework using Finite Elements Analysis (FEA) together with Geometric Morphometrics. In this work we explored the relationship between the mandibular shape (analysed by Geometric Morphometrics methods) and biomechanics (quantified with Finite Element Analysis) of almost 30 species belonging to 10 families of Carnivora in an evolutionary context. For FEA a novel approach was used, generating 100 variables representing equal ranges of stress values. Two cases were analysed, the first one analysing the stress values when the force was applied in the canine (Set 1), and the second one the force simulated in a more posterior place of the tooth row (Set 2). A Principal Component Analysis (PCA) of the shape data showed low integration and many directions of change, with only PC2 partially related with diet. Shape data had phylogenetic signal. On the contrary, most FEA variables were not related to the phylogeny. There was a certain degree of covariation between shape and stress levels. For Set 1, this covariation turns out to be non-significant when phylogeny is taken into account. However, for Set 2 this relationship, although smaller, is maintained when considering the phylogeny. Taking all the evidence into account, our results suggested that phylogeny played an important role in carnivoran jaw shape evolution. On the other hand, biomechanical variables were more correlated with diet and more independent of phylogeny. As FEA is affected by shape, the conclusion is that not all the shape variability was related with function, and other factors are probably involved. Combining information from both sets shed light into specific adaptations and point out the importance of using different biomechanical hypothesis to biologically analyse FE results. Our results are preliminary and describe broad scale evolutionary patterns, as just a small fraction of Carnivora is represented here. Adding more species to the analysis will prove whether the observed patterns apply at smaller scales (e.g. within tribes and genera)