A finite element approach to the biomechanics of dromaeosaurid dinosaur claws

P. L. Manning, L. Margetts, M. Johnson, Z. Mustansar, Paul Mummery

    Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

    Abstract

    Dromaeosaurid theropod dinosaurs possessed strongly recurved, hypertrophied and hyperextensible ungual claws on both the pes (digit II) and manus. The morphology of these unguals has been linked to the capture and dispatching of prey. The effectiveness of the enlarged pedal digit II ungual as a disemboweling implement has been challenged by recent experiments using a hydraulic reconstruction of a dromaeosaurid hind limb. However, the mechanical properties or, more importantly, the mechanical potential of these structures have not been explored. The generation of a 3D finite element (FE) stress/strain contour map of a Velociraptor manual ungual has for the first time allowed quantitative evaluation of the mechanical behavior of a dromaeosaurid terminal ungual phalanx. The role of the finite element analysis was to test the relationship of form and function, from an engineering point of view. X-ray microtomography scans have allowed the construction of an accurate 3D finite element mesh. Analogue biomaterials from an extant avian theropod, the pedal digit and claw of an eagle owl (Bubo bubo), were analysed to provide input data for the Velociraptor claw FE model. The resultant finite element model confirms that claws of dromaeosaurid dinosaurs were well-adapted for climbing as they would have been resistant to forces acting in a single (longitudinal) plane, in this case due to gravity. However, the strength of an ungual claw was limited with respect to forces acting tangential to the longaxis of the structure. The tip of the claw functioned as the puncturing and gripping element of the structure, while the expanded proximal portion transferred the load stress through the cortical and cancellous bone. Claw form and function varies widely among vertebrates however, claw sheath composition does not. The possession of a keratinous sheath also played an integral role in the distribution of load stress into the bone core of the claw. The proposed enhanced climbing abilities of dromaeosaurid dinosaurs, a function of pedal morphology, support a scansorial phase in the evolution of flight.
    Original languageEnglish
    Title of host publicationJournal of Vertebrate Paleontology,Vol 29, Supplement to No.3, September 2009
    PublisherTaylor & Francis
    Pages141-141
    Number of pages1
    Publication statusPublished - 26 Sept 2009
    EventThe Society for Vertebrate Paleontology 69th Annual Meeting - University of Bristol, Bristol, United Kingdom
    Duration: 23 Sept 200926 Sept 2009

    Conference

    ConferenceThe Society for Vertebrate Paleontology 69th Annual Meeting
    CityUniversity of Bristol, Bristol, United Kingdom
    Period23/09/0926/09/09

    Keywords

    • Finite element analysis
    • Microstructurally faithful modelling
    • Velociraptor
    • Claw

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