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Abstract :
[en] Throughout geological times, multiple clades converged in craniodental morphology with true cats (Felidae), notably nimravids and thylacosmilids. In those groups, the so-called sabre-tooth phenotypes is a textbook example of convergent evolution often interpreted as an adaptation for subduing large prey. This conventional framework implies homogenous ecologies for all sabre-toothed clades, failing to consider the functional differences between scimitar-toothed, dirk-toothed and ‘mosaic’ taxa, as well as the numerous species that convergently evolved smaller, conical canines. This simplified interpretation of the seemingly unique saber-tooth condition is reinforced by a reduced taxonomic sampling in some studies, often focusing on a couple of well-known, highly derived taxa or using highly-simplified morphological models. Moreover, most biomechanical analyses focus on biting scenarios at small gapes (25 to 30°), a classical angle for modern carnivora that is however ill-suited to test for subduction of large prey by sabre-toothed taxa.
Here, we thoroughly analyse the biting biomechanics of sabre-toothed and non-sabre-toothed taxa by applying Finite Element Analyses (FEA) on the largest dataset ever assembled of cat-like placental mandible 3D models, under a variety of gape scenarios. We performed muscle-induced biting simulations on 17 different taxa, at three different angles (30°, 60° and 90°), and on multiple biting points to evaluate their adaptation to bite at large angle; the total number of biting simulations we performed reaches 1,074. While our results show a clear adaptation of extreme sabre-toothed taxa to bite at larger angles in terms of Von Mises stress, other performance variables (mechanical efficiency and adjusted strain energy) display surprising similarities between sabertoothed and non-sabertoothed forms between the different angles tested, highlighting a continuous rather than bipolar spectrum of hunting methods in cat-like carnivorans.
