The field of functional morphology analyses the relationship between anatomical form and organismal function and behaviour. In fossil organisms, function is often difficult to reconstruct. However, by using a range of biomechanical modelling techniques, such as Finite Element Analysis (FEA) or Multibody Dynamics Analysis (MDA), coupled with CT scanning and digital visualisation, it is possible to investigate the form/function-relation of extinct animals. These techniques are particularly powerful tools to not only compare different skeletal morphologies, but also to test hypothetical models and different behavioural scenarios.

Biomechnical behaviour of the skull of Erlikosaurus andrewsi without and with keratinous beak using Finite Element Analysis

   Using Finite Element Analysis, we investigated the skull of Erlikosaurus andrewsi – a 3-4 m (10-13 ft) large herbivorous dinosaur called a therizinosaur, which lived more than 90 million years ago during the Cretaceous Period in what is now Mongolia, and which shows evidence that part of its snout was covered by a keratinous beak. The biomechanical simulations of Erlikosaurus andrewsi allow testing different skull configurations (with and without keratinous beak), as well as different feeding scenarios. This approach provided accurate results how bite and muscle forces affected the skull of Erlikosaurus during the feeding process and permitted to reconstruct the possible feeding behaviour of Erlikosaurus andrewsi.


Reconstructed feeding behaviour of Erlikosaurus andrewsi using the jaw and neck musculature in combination

   Results of this study further indicated that the development of beaks and the presence of a keratinous rhamphotheca would have helped to dissipate stress and strain, making the rostral part of the skull less susceptible to bending and displacement. This suggests that keratinous beaks thus represent an evolutionary innovation developed early in derived theropods to enhance cranial stability, distinct to postulated mass-saving benefits associated with the origin of flight

The skull of Erlikosaurus andrewsi in response to bite forces. Red areas indicate regions of high stress

More information on this study can be found here:
Lautenschlager, S., Witmer, L. M., Altangerel, P., Rayfield, E. J. (2013): Edentulism, beaks, and biomechanical innovations in the evolution of theropod dinosaurs. PNAS.
DOI: 10.1073/pnas.1310711110

Lautenschlager, S. (2014): Morphological and functional diversity in therizinosaur claws and the implications for theropod claw evolution. Proceedings of the Royal Society B, 281, 20140497. DOI: 10.1098/rspb.2014.0497


Dr. Stephan Lautenschlager
School of Earth Sciences
University of Bristol
Life Sciences Building
24 Tyndall Avenue
Bristol BS8 1TQ
United Kingdom
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