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Mobility and Hydrodynamic Implications of the Long Neck in Plesiosaurs

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Mobility and Hydrodynamic Implications of the Long Neck in Plesiosaurs Mobility and hydrodynamic implications of the long neck in plesiosaurs PERNILLE V. TROELSEN A thesis submitted in partial fulfilment of the requirements of Liverpool John Moores University for the degree of Doctor of Philosophy December 2018 Contents Acknowledgements ................................................................................................................ 7 List of Tables........................................................................................................................ 10 List of Figures ...................................................................................................................... 11 Abstract ................................................................................................................................ 17 Institutional abbreviations .................................................................................................... 18 Chapter 1 - Introduction ....................................................................................................... 19 1.1 Part A: Plesiosaur palaeobiology................................................................................ 19 1.1.1 Introduction .......................................................................................................... 19 1.1.2 Overview of the history of plesiosaur research ................................................... 19 1.1.3 Plesiosaurian diversity and morphology .............................................................. 24 1.1.4 Phylogeny, taxonomy and ecological categorisation ........................................... 47 1.1.5 Foraging and feeding strategies ........................................................................... 52 1.2 Part B: Long necks in extant vertebrates .................................................................... 59 1.2.1 Introduction .......................................................................................................... 59 1.2.2 Neck morphology in extant vertebrates ............................................................... 59 1.2.3 Main differences between terrestrial and aquatic necks ...................................... 76 1.3 Conclusion .................................................................................................................. 78 Chapter 2 – Range of motion in ostrich necks ..................................................................... 79 2.1 Introduction ................................................................................................................ 79 2.1.1 Range of motion studies of necks in extant animals ............................................ 80 2.1.2 Long necks in extant animals............................................................................... 87 2.2 Materials and methods ................................................................................................ 89 2.2.1 Physically manipulated neck ............................................................................... 89 2.2.2 Digitally manipulated neck .................................................................................. 92 2.3 Results ........................................................................................................................ 93 2.4 Discussion .................................................................................................................. 99 2 2.4.1 Physically manipulated neck ............................................................................... 99 2.4.2 Digitally manipulated neck ................................................................................ 101 2.4.3 Comparing the two methods .............................................................................. 101 2.5 Conclusions .............................................................................................................. 103 Chapter 3 – Range of motion in plesiosaur necks .............................................................. 104 3.1 Introduction .............................................................................................................. 104 3.1.1 Plesiosaur neck morphology .............................................................................. 104 3.1.2 Previous studies on neck flexibility in plesiosaurs ............................................ 111 3.1.3 Rationale of the present study ............................................................................ 114 3.2 Materials and methods .............................................................................................. 115 3.2.1 Specimens .......................................................................................................... 115 3.2.2 Photogrammetry................................................................................................. 115 3.2.3 Attaining range of motion data .......................................................................... 116 3.3 Results ...................................................................................................................... 118 3.4 Discussion ................................................................................................................ 128 3.4.1 Neck movement in plesiosaurs .......................................................................... 128 3.4.2 Plesiosaur ecology and other aspects of biology ............................................... 132 3.5 Conclusions .............................................................................................................. 133 Chapter 4 – Fluid dynamics ............................................................................................... 134 4.1 Introduction .............................................................................................................. 134 4.1.1 Fluid dynamics ................................................................................................... 134 4.1.2 Computational Fluid Dynamics ......................................................................... 143 4.2 Validation experiments ............................................................................................. 156 4.2.1 Methods ............................................................................................................. 156 4.2.2 Results with respective approaches ................................................................... 157 4.3 Conclusions .............................................................................................................. 175 3 Chapter 5 – The hydrodynamic implications of neck elongation and thickness in plesiosaur necks ................................................................................................................................... 177 5.1 Introduction .............................................................................................................. 177 5.1.1 Soft tissue in plesiosaurs .................................................................................... 177 5.1.2 Hydrodynamics .................................................................................................. 179 5.1.3 Computational Fluid Dynamics ......................................................................... 179 5.2 Materials and methods .............................................................................................. 180 5.2.1 Selected plesiosaur species ................................................................................ 180 5.2.2 Modelling the plesiosaur .................................................................................... 181 5.2.3 Computational fluid dynamics simulations ....................................................... 182 5.3 Results ...................................................................................................................... 184 5.4 Discussion ................................................................................................................ 186 5.4.1 Neck elongation and thickness .......................................................................... 186 5.4.2 Ecology and behaviour of plesiosaurs ............................................................... 188 5.5 Conclusions .............................................................................................................. 190 Chapter 6 – Hydrodynamic effects of plesiosaurs bending the neck during forward motion ............................................................................................................................................ 191 6.1 Introduction .............................................................................................................. 191 6.2 Methods .................................................................................................................... 193 6.2.1 Building the plesiosaur models .......................................................................... 193 6.2.2 Characteristic length for a plesiosaur model with bent neck ............................. 198 6.2.3 Computational fluid dynamics ........................................................................... 199 6.3 Results ...................................................................................................................... 201 6.3.1 Effect of bending location and distribution using primitives ............................ 201 6.3.2 Effects of bending the neck in idealized plesiosaur models .............................. 202
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