The work “Finite elements analysis of the cingulate lower jaw” was presented in the 10th European Association of Vertebrate Palaeontologists Meeting held in Villers-sur-Mer (France) from the 11st to the 15th of June. The authors of the work are Sílvia Serrano-Fochs, Soledad De Esteban-Trivigno, Jordi Marcé-Nogué, Josep Fortuny and Richard Fariña form the Institut Català de Paleontologia (www.icp.cat), Transmitting Science (http://www.transmittingscience.org/) the BarcelonaTech Universtitat Politècnica de Catalunya (www.upc.edu) and Universidad de La República of Urugauay (www.universidad.edu.uy).
Finite element analysis (FEA) allows simulating the biomechanical behavior of biological structures, in order to understand how they react under different loads. This technique has been shown very useful in paleontology, as it allow researchers to test their functional hypothesis. The mammalian order Xenarthra comprises a group of peculiar placental mammals forming a monophyletic group with highly heterogeneous morphology. It includes the suborders Cingulata and Pilosa, comprising the extant anteaters, armadillos and tree sloths. The aim of this work is to evaluate the biomechanical capabilities of the Cingulate lower jaw in a comparative framework, and to test if there are a relationship between diets and the stress pattern of the mandibles. To achieve this, FEA on planar models of the lower jaw of 14 Cingulate species (three of them extinct) have been developed. The hypothesis proposed is that, for equivalent forces, species with diet requiring less processing (e.g. insects) would display a lower jaw showing a higher stress level than species with more processing requirements (e.g. herbivorous). Omnivores and herbivorous species, as predicted by the hypothesis, show lower levels of stress than most insectivores. However, some insectivores display a stress pattern more similar to omnivores, which is probably due to the limited information about its natural history. On the other hand, D. novemcinctus, display a relatively weak lower jaw, in clear disagreement with the variety of items ingested by this species. This suggests that other mechanisms different than mastication may be involved in the food processing of this species. The results support the use of FEA for functional analysis, showing it as a really valuable tool in paleobiology. However, “Evolution is a tinkerer”, and sometimes it may find alternative solutions to develop certain functions, not related with the structure analyzed, as in D. novemcinctus case.