An investigation of tetrapod skull architecture using advanced computer modelling techniques
Lead Research Organisation:
University College London
Department Name: Cell and Developmental Biology
Abstract
The skulls of animals must balance the conflicting demands of strength and stability with flexibility, so that they can open their mouths as wide as possible and apply a maximum bite force without damaging the enclosed brain and sense organs. Ancestors of reptiles, birds and mammals had a solid skull except for eye and ear openings, but they soon began to develop openings (fenestrae) in the side of the skull behind the eyes; now different skulls have different patterns of fenestrae, but it is still not understood why. Furthermore the overall geometries of skulls are different. There is variation in skull depth, in the size of the brain and/or sense organs, in the complexity of the jaw muscles, and in the length of the neck. All of these features, individually or in combination, have a major effect on skull function (biomechanics) and may underlie the radical differences in skull architecture of living animals. The aim of this research is to understand the relationship between biomechanical forces and skull shape in living animals, and in particular to determine the biomechanical significance of skull fenestrations. To do this work, we need to combine the expertise of mechanical engineers, digital imagers, bone biologists, and morphologists, and use advanced computer modelling techniques to perform sophisticated biomechanical analyses. In this project, information from museum specimens of living animal groups (obtained by advanced computer imaging - High Resolution Computed X-ray Tomography) will be combined to develop accurate models of a range of skulls. These can be modified to change basic parameters (e.g. eye size, brain size, patterns of fenestration), and then loaded in ways that simulate changing complexities of the jaw and neck muscles, changes in size of the brain and sense organs, and/or increasing bite force. As a result, we can, for the first time, test a series of theories to explain skull shape. Not only will the study advance our knowledge of the development of a key group of organisms but it will also deepen our understanding of the complex relationship between biomechanical forces, soft tissue structures and skeletal shape. Understanding this complex relationship is important, not only to general biology but also to medicine (e.g. bone repair and remodelling, over-use injuries, osteoporosis).
Technical Summary
For land tetrapods, it is widely accepted that key anatomical features of the skull (e.g. diagnostic holes, fenestrae, emarginations) are genetically regulated and serve specific purposes (are adaptive). However, some of these features may be secondary phenomena reflecting optimisation of skull structure to the combined effects of stress (from jaw and neck muscles, from biting) and the changing proportions of the enclosed brain and sense organs. This impacts on our understanding of the extent to which skull features are there because they serve a particular function or are secondary mechanically or genetically mediated optimisations of form to function. This is a key biological issue. It requires an intimate understanding of cranial and bone biomechanics, structure, comparative function, and developmental biology, a range of expertise that can only be offered by a cross-disciplinary approach. We propose to undertake the first comprehensive study of skull form and function using a hybrid MDA/FEA approach to test a series of hypotheses relating to the biomechanical significance of fenestration and/or emargination. Multibody dynamics analysis (MDA) will be used to calculate the external forces and internal musculature arising during normal skull loading. Finite element analysis (FEA) and a unique adaptive FEA approach developed at Hull (BMU-SIM) will then be used to model the skulls and test their response to varying patterns of stress/strain that result from enlargement of the brain and/or sense organs, increased complexity of jaw muscles, and the presence of a mobile neck. We have access to skull data obtained by High Resolution X-ray CT and to a supercomputer powerful enough for highly detailed static and adaptive skull remodelling studies. This pioneering research will also be the first to model in detail effects of cranial sutures on skull biomechanics and function.
Organisations
People |
ORCID iD |
Susan Evans (Principal Investigator) |
Publications
Curtis N
(2010)
Predicting muscle activation patterns from motion and anatomy: modelling the skull of Sphenodon (Diapsida: Rhynchocephalia).
in Journal of the Royal Society, Interface
Curtis N
(2010)
Feedback control from the jaw joints during biting: an investigation of the reptile Sphenodon using multibody modelling.
in Journal of biomechanics
Curtis N
(2013)
Cranial sutures work collectively to distribute strain throughout the reptile skull.
in Journal of the Royal Society, Interface
Curtis N
(2010)
Comparison between in vivo and theoretical bite performance: using multi-body modelling to predict muscle and bite forces in a reptile skull.
in Journal of biomechanics
Jones ME
(2012)
Shearing mechanics and the influence of a flexible symphysis during oral food processing in Sphenodon (Lepidosauria: Rhynchocephalia).
in Anatomical record (Hoboken, N.J. : 2007)
Jones ME
(2012)
The head and neck anatomy of sea turtles (Cryptodira: Chelonioidea) and skull shape in Testudines.
in PloS one
Lappin AK
(2014)
Reliable quantification of bite-force performance requires use of appropriate biting substrate and standardization of bite out-lever.
in The Journal of experimental biology
Marc Jones (Author)
(2011)
Cranial joint morphology in Sphenodon (Lepidosauria: Diapsida: Rhynchocephalia), sutures and kinesis.
in Palaeontologica Electronica
Marc Jones (Author)
(2009)
The head and neck muscles associated with feeding in Sphenodon (Reptilia: Lepidosauria: Rhynchocephalia).
in Palaeontologica Electronica
Description | a) A sophisticated protocol for the generation and analysis of anatomically detailed 3-D hybrid FEA/MDA models of Sphenodon (turtles ongoing) that are highly informative with respect to the relationship between hard and soft tissues, including the importance of muscle orientation and internal organisation. PCSA (physiological cross-sectional area), often used as a proxy for muscle strength, is problematic in animals with highly pinnate muscles. b) A much improved understanding of cranial sutures, as to their local effect (in strain reduction), their total effect (in equilibrating strain across the skull), the detailed relationship between suture structure and function, and the general differences in suture morphology between different groups of reptiles. |
Exploitation Route | We ourselves took these findings forward into a second project focusing on skull flexibility and are planning further work on cranial soft tissues and their biomechanics. Our Hull collaborators took this forward with a project on craniosynostosis |
Sectors | Education,Healthcare,Leisure Activities, including Sports, Recreation and Tourism,Culture, Heritage, Museums and Collections |
Description | In public engagement talks to audiences in the UK and China (as part of Darwin celebrations) In designing a project on craniosynostosis (Hull) |
Sector | Education,Culture, Heritage, Museums and Collections |
Impact Types | Cultural,Societal |
Description | The role of skull flexibility in feeding - an investigation using advanced computer modelling techniques. |
Amount | £365 (GBP) |
Funding ID | BB/H011854/1 |
Organisation | Biotechnology and Biological Sciences Research Council (BBSRC) |
Sector | Public |
Country | United Kingdom |
Start | 07/2010 |
End | 06/2013 |
Description | Online report for BBSRC website |
Form Of Engagement Activity | A magazine, newsletter or online publication |
Part Of Official Scheme? | No |
Geographic Reach | National |
Primary Audience | Professional Practitioners |
Results and Impact | Prepared online submission for BBSRC website N/A |
Year(s) Of Engagement Activity | 2012 |
URL | http://www.bbsrc.ac.uk/news/fundamental-bioscience/2012/120606-n-chewing-not-just-for-mammals.aspx |
Description | Public talk |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | Local |
Primary Audience | Public/other audiences |
Results and Impact | Public talk at the Natural History Museum London, under the Nature Live series. March 2013. The tuatara of New Zealand. By PDRA MEH Jones n/a |
Year(s) Of Engagement Activity | 2013 |
Description | The role of skull flexibility in feeding |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Public/other audiences |
Results and Impact | We have presented aspects of this work to a variety of academic seminar audiences, student audiences (open days, international student forums) and non-academic audiences This includes several presentations to groups of undergraduate students, postgraduate students on research induction, visiting school students and visiting members of the International Student Forum for science students Enquiries from media; visiting undergraduate interns; visiting school work experience students. |
Year(s) Of Engagement Activity | 2007,2008,2009,2010,2011,2012,2013 |