Supplementary material from "Does the model reflect the system? When two dimensional biomechanics is not ‘good enough.’"

  • Amanda L. Smith (Creator)
  • Julian Davis (Creator)
  • Olga Panagiotopoulou (Creator)
  • Andrea B. Taylor (Creator)
  • Chris Robinson (Creator)
  • C. V. Ward (Creator)
  • William H. Kimbel (Creator)
  • Zeresenay Alemseged (Creator)
  • Callum F. Ross (Creator)



Models are mathematical representations of systems, processes, or phenomena. In biomechanics, finite-element modelling (FEM) can be a powerful tool, allowing biologists to test form-function relationships in silico, replacing or extending results of in vivo experimentation. Although modelling simplifications and assumptions are necessary, as a minimum modelling requirement the results of the simplified model must reflect the biomechanics of the modelled system. In cases where the three-dimensional mechanics of a structure are important determinants of its performance, simplified two-dimensional modelling approaches are likely to produce inaccurate results. The vertebrate mandible is one among many three-dimensional anatomical structures routinely modelled using two-dimensional FE analysis. We thus compare the stress regimes of our published three-dimensional model of the chimpanzee mandible to a published two-dimensional model of the chimpanzee mandible and identify several fundamental differences. We then present a series of two-dimensional and three-dimensional FE modelling experiments that demonstrate how three key modelling parameters; (1) dimensionality, (2) symmetric geometry, and (3) constraints affect deformation and strain regimes of the models. Our results confirm that, in the case of the primate mandible (at least), two-dimensional FEM fails to meet this minimum modelling requirement and should not be used to draw functional, ecological or evolutionary conclusions.
Date made available2022
PublisherThe Royal Society

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