menacing in Spielberg's Jurassic Park. The novelty of the research is that it seeks to reveal new insights by bringing together advanced techniques from a ...
Computer aided insights into biomechanics of dinosaurs Significance and Relevance of the Topic The poster presents research that seeks to clarify, from a biomechanical viewpoint, the form and function of a Velociraptor manus claw. Velociraptor is the dinosaur portrayed as intelligent and menacing in Spielberg’s Jurassic Park. The novelty of the research is that it seeks to reveal new insights by bringing together advanced techniques from a number of disciplines to investigate the biomechanics of dinosaurs. The function of dinosaur claws has been debated over the last 100 years, with some experts believing them to perform a disembowelling function and others that they were used as a climbing crampon. In recent work by Manning et al. (2006), a hydraulically powered mechanical hind limb was used to show that a Dromaeosaur claw would cause a puncture wound to potential prey, rather than cause any life threatening damage.
Problem and Motivation The previous study provides no insight into the mechanical behaviour of the claw and the author is undertaking further work to fully understand form and function. An important piece of the jigsaw puzzle is the requirement that stresses are kept within safe limits for all biological materials subject to loading (Alexander 1981). In other words, it is likely that dinosaur claws would be able to withstand the stresses encountered during normal usage. By using computer aided engineering techniques, it is possible to test a number of different scenarios, quantifying the stresses generated within the claw and eliminating those scenarios where form could not match function. The tools and techniques being used in this research include: 1. Computer aided X-ray tomography to digitise the geometry and internal microstructure of the claw. This is similar to medical imaging. 2. Computerised image reconstruction and processing to create models for computer aided engineering: methods originally developed for car crash simulations. 3. Laboratory based determination of material properties from present day birds. 4. Physics based modelling using supercomputers and virtual reality. High resolution models are needed to capture the detailed internal microstructure.
Approach and Uniqueness The reader will appreciate that there are a number of unique philosophical and societal aspects to this work. For example, the use of advanced computing techniques in palaeontology gives mankind a unique opportunity to fully unravel the mysteries of extinct organisms, giving a level of insight into the past that until now has only been possible for the present. Perhaps more profoundly, the work uses society's fascination with dinosaurs as a platform to educate the general public regarding the technology that is today available for scientific research. This understanding will surely help society better manage the expectations that are placed on scientists.
Related work and Background Fossilisation normally preserves the hard parts of living organisms only. In the case of dinosaur claws, this is the internal bone. The external keratinous sheath is not preserved. However, using computer aided engineering tools; it is straightforward to add this sheath, along with muscles and tendons, to the model. Bone is a composite structure which has the ability to withstand compressive and tensile deformation as well as bending. Nonetheless, like concrete, bone is mechanically strongest in compression. In 1
contrast, keratin is strong in extension as the collagen fibrils are organised in lamellae. Thus, the claw bone with a keratinous outer sheath is a composite structure in which the keratin is analogous to steel reinforcements in concrete, helping the bone to resist tensile and bending stresses. The skeletal elements of organisms have evolved margins of safety in terms of their strength. Safety factors (Biewer 1993) are calculated through the relationship between the load that the bone can bear and the loads encountered in life. In engineering terms, by calculating a structure’s failure strength, it is possible to determine the maximum allowable stress expected during use. The research seeks to determine these safety factors, by loading the virtual claw until failure.
Results and Contributions One key advantage of computer modelling is that it is straightforward to undertake as many experiments as needed, to eliminate uncertainties in the input data. These uncertainties include the values of the material properties used and the thickness of the keratin sheath. There are no living dinosaurs to test or observe. Image based modelling techniques have generated much interest in the field of palaeontology and beyond. For example, the same techniques are being used to design new materials for high performance engineering applications in the transport and energy sectors. This is a good example of how ‘blue-skies’ research can have a direct impact upon industrial applications. Moreover the multidisciplinary nature of the work promotes advances in science that would not otherwise be possible. Finally the research has benefits for the social good. The general public are fascinated with dinosaurs and the research is sure to fire the imagination of all humankind, across all the four corners of the Earth.
Figure A: X-Ray Images of Velociraptor Manus Claw
Figure B: Processing
Figure C: Results
References BIEWENER A. A. 1993. Safety Factors in Bone Strength. Calcif Tissue Int 53(Suppl 1):S68-S74 MANNING P. L., PAYNE D., PENNICOTT J. and BARRETT P. 2006 Dinosaur killer claws or climbing crampons? Royal Society Biology Letters, 2 (1), 110-112. ALEXANDER RM. 1981. Factors of safety in the structure of animals. Sci Prog; 67(265):109-30.
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