Cranial biomechanics of Diplodocus (Dinosauria, Sauropoda): testing hypotheses of feeding behaviour in an extinct megaherbivore
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Sauropod dinosaurs were the largest terrestrial herbivores and pushed at the limits of vertebrate biomechanics and physiology. Sauropods exhibit high craniodental diversity in ecosystems where numerous species co-existed, leading to the hypothesis that this biodiversity is linked to niche subdivision driven by ecological specialisation. Here, we quantitatively investigate feeding behaviour hypotheses for the iconic sauropod Diplodocus. Biomechanical modelling, using finite element analysis, was used to examine the performance of the Diplodocus skull. Three feeding behaviours were modelled: muscle-driven static biting, branch stripping and bark stripping. The skull was found to be ‘over engineered’ for static biting, overall experiencing low stress with only the dentition enduring high stress. When branch stripping, the skull, similarly, is under low stress, with little appreciable difference between those models. When simulated for bark stripping, the skull experiences far greater stresses, especially in the teeth and at the jaw joint. Therefore, we refute the bark-stripping hypothesis, while the hypotheses of branch stripping and/or precision biting are both consistent with our findings, showing that branch stripping is a biomechanically plausible feeding behaviour for diplodocids. Interestingly, in all simulations, peak stress is observed in the premaxillary–maxillary ‘lateral plates’, supporting the hypothesis that these structures evolved to dissipate stress induced while feeding. These results lead us to conclude that the aberrant craniodental form of Diplodocus was adapted for food procurement rather than resisting high bite forces.
KeywordsFinite element analysis Palaeobiology Herbivory Sauropod dinosaur
We thank Clint Davies-Taylor and Neil Gostling for their computing assistance, Karl Niklas and Steven Vogel for their discussion on plant biomechanics, Mike Brett-Surman and Amy Henrici for specimen access, Heather Rockhold for CT scanning and John Whitlock and an anonymous reviewer for their comments on a previous version of this article. We gratefully acknowledge the financial support of the Natural Environment Research Council (NER/S/A/2006/14058) and the Natural History Museum London (awarded to EJR and PMB) and the National Science Foundation (IBN-0407735 to LMW and CMH, and IBN-0343744 and IOB-0517256 to LMW).
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