The ‘death roll’ of giant fossil crocodyliforms (Crocodylomorpha: Neosuchia): allometric and skull strength analysis

Abstract

In the evolution of crocodylomorphs, there were at least three giant-dimension genera: Deinosuchus from late Cretaceous of North America, Sarcosuchus from middle Cretaceous of Africa and South America, and Purussaurus from Miocene of South America. It has been suggested that these predators could have fed on very large prey as dinosaurs and megamammals. The ‘death roll’ is a spinning manoeuver executed to subdue and dismember large prey; therefore, it has been previously suggested that giant cocrodylomorphs may have used this manoeuver. However, this manoeuver can generate torsional stresses in the skull. We propose a biomechanical model to estimate the capability of a crocodylomorphs for withstanding this torsional stresses. Our results show a good correlation between a ‘death roll’ capability indicator and the feeding categories related with the actual use of ‘death roll’ in 16 living species. Here, for the first time, we propose a biomechanical approach of the implications of ‘death roll’ in fossil crocodylomorphs. We suggest that Deinosuchus and Purussaurus were able to execute death roll over dinosaurs and large mammals, respectively, but Sarcosuchus probably was not. We also found some allometry effects and, finally, we discuss palaeobiological implications based on our results.

Keywords::

• palaeobiology
• biomechanics
• ‘death roll’
• crocodiles

Acknowledgements

The authors thank PEDECIBA, ANII and Espacio Interdisciplinario, Universidad de la República for financial support, and Museo Nacional de Historia Natural for providing specimens. The authors thank Luciano Verdade for his valuable observations and comments about South American crocodiles. The authors also thank Claudio Borteiro and William E. Magnusson for their comments about C. latirostris and C. crocodilus, respectively.