Finite Element Analyses of Ankylosaurid Dinosaur Tail Club Impacts

Authors

  • Victoria M. Arbour,

    Corresponding author
    1. Department of Biological Sciences, Biological Sciences Centre, University of Alberta, Edmonton, Alberta, Canada
    • Department of Biological Sciences, CW 405 Biological Sciences Centre, University of Alberta, Edmonton, Alberta, Canada T6G 2E9
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  • Eric Snively

    1. Department of Biological Sciences, Biological Sciences Centre, University of Alberta, Edmonton, Alberta, Canada
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Abstract

Ankylosaurid dinosaurs have modified distal caudal vertebrae (the handle) and large terminal caudal osteoderms (the knob) that together form a tail club. Three-dimensional digital models of four tail clubs referred to Euoplocephalus tutus were created from computed tomography scans of fossil specimens. We propose to use finite element modeling to examine the distribution of stress in simulated tail club impacts in order to determine the biological feasibility of hypothesized tail clubbing behavior. Results show that peak stresses were artificially high at the rigid constraint. The data suggest that tail clubs with small and average-sized knobs were unlikely to fail during forceful impacts, but large clubs may have been at risk of fracture cranial to the knob. The modified handle vertebrae were capable of supporting the weight of even very large knobs. Long prezygapophyses and neural spines in the handle vertebrae helped distribute stress evenly along the handle. We conclude that tail swinging-behavior may have been possible in Euoplocephalus, but more sophisticated models incorporating flexible constraints are needed to support this hypothesis. Anat Rec, 292:1412–1426, 2009. © 2009 Wiley-Liss, Inc.

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