THE UNIVERSITY OF CALGARY Eric Snively A ... - Ohio University

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y distal intermetatarsal ligaments, its proximal splint was in danger of breaking under moderate locomotory loadings. FEA and ligament-skeletal dynamics Successful application of bone strain analysis (Chapter 4) is encouraging for the use of finite elements in the palaeontological study of ligament function. Finite element analysis incorporating bones, ligaments, tendons, and muscles will aid in the overall investigation of kinematics in extinct animals. The complete locomotor repertoire has yet to be circurnscribed for any extant animal, much less for a Mesozoic dinosaur. However, neontologically infonned finite element modeling will be a useful tool for elucidating the locomotor systems of extinct animals. The next section details the importance of these investigations, by showing how the biomechanical role of the arctometatarsus influences broader questions of evolution and behaviour. REDUCTION AND SYNTHESIS OF THE ARCTOMETATARSUS AS A BIOMECHANCAL SYSTEM Descriptive morphology, qualitative modeling, quantitative testing Chapters 2, 3, and 4 tentatively elucidated foot function in tyrannosaurids. The primary impediments to this and other functional studies of extinct animals are the imprecision of sof? tissue reconstruction, and the dearth of performance data. The methodological scope is much greater for neontological studies, which have a wider array of available modeling and statistical approaches. Because the performance of living organisms a n be measured, it is possible to compare their
individual organs with ideally efficient models, and to compare the collective performance of organs with models of compromised efficiency (Zweers 1979). It is also possible to correlate measured performance with morphometric attributes, such as dinging ability with size and zeugopodial morphology in lizards (Zani 2000). These studies cm incorporate aspects of neurology (Zweers 1991 ) that are impossibie with extinct organisms, except by broad inference (Giffin 1990, 1992; Martin et al. 1998). Assessments of absolute or realized performance are extremely difFicult with fossil animals. Therefore, hypotheses of function must be refined in focus through the accumulation of inductive data, using cornparisons with other extinct and extant taxa. For example, in this study of the arctometatarsus, a broad hypothesis of difference from other forms was tested through detailed morphological description and PCA of theropod third metatarsals. The distribution of ostealo~ical correlates suggested that ligaments arrested anterior displacement of MT Il1 in tyrannosaurids, in the manner of interosseous ligaments that bind the intercalating carpals of horses. This proposed function was refined into the tensile keystone hypothesis, and finite element analysis quantitatively tested the resulting kinematic model. Through this progression, a hypothesis of arctometatarsus function emerged that is based on thorough morphologicai understanding, and that is amenable to further quantitative falsification or support. I now briefiy recapitulate and synthesize these findings for tyrannosaurids, and discuss their implications for other theropods.
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THE UNIVERSITY OF CALGARY Functiona
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Many figures in this thesis use col
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ACKNOWLEûGEM ENTS Many friends and
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Approval page Acknowledgements Tabi
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CONCLUDING COMMENTS Figures for Cha
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CHAPTER 5: Mechanical and phylogene
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LIST OF FIGURES Figure 1 .l. Phylog
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Figure 3.6. Osteological correlates
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AMNH GI HMN IVPP MOR NMC OMNH PIN P
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and constructional morphology revea
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1985, Bryant and Seymour 1990). If
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surfaces of a Tyrannosaurus rex spe
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3. Troodontidae (Figure 1.2): Trwdo
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Hypothesized functions of the tyran
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1. Atomization (Chapters 2 and 3).
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Figure 1.1. P hylogenetic diagram o
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Figure 1.2. Phylogenetic diagram of
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Figure 1 .S. Skeletal restorations
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did not quantify the degree of prox
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qualitative debate over arctometata
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This hypothesis focuses on tyrannos
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Table 2.1. Theropod and Plafeosauru
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specimens in the figures reflects a
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were not attempted. While this limi
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Chapter 3). 1 now address variation
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- Ç6'P 1 68'€tr 1 L'OC 99'66 L'9
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Table 2.3: Log-transformed values f
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experiences a sharp laterally indin
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ecause it can be cursorily dassifie
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arctometatarsalian specimens, the l
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) Shaf€ and region of proximal ar
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a) Ginglymus. Figure 2.14 shows the
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) Shaft and region of proximal arti
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measurements of width pV2S%TU-DE an
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Table 2.4b Variancelmeasurement eac
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the largest sum of linear measureme
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Table 2.5: Specimen statistics Herr
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and Sinraptor dongi specimens. With
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In addition, a hook like proximal a
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oth physical narrowing and elongati
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1s the MT 111 shape segregation fun
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tyrannosaurids, ornithomimid, and t
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proximal constriction, white EImisa
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Figure 2.2. Tyrannosaurid, trwdonti
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Figure 2.4. Dromaeosaurid and carno
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- Anterior (flexor) surface medial
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Figure 2.7. Left MT III of Tyrannos
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Figure 2.8. Left MT III of Gorgosau
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Figure 2.9. Left MT III of an omith
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Figure 2.10. Left metatarsus of Tmd
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Figure 2.1 1. Left MT III of Elmisa
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Figure 2.12. Right MT III of Deinon
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Figure 2.13. Left MT III of Allosau
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Figure 2.14. Left metatarsus of Sin
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Figure 2.15. Plots of MT Ill specir
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Figure 2.16. Plot of third metatars
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tv . ... . Ri. . . .
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Figure 2.19. Plot of third metatars
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CHAPTER 3: Tensile keystone model o
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dynamically transmitted Iommotor fo
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Table 3.1 . Metatarsi examined in t
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interrnetatarsal dynamics in these
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compelled analysis of movement evid
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Once prepared, TMP 94.1 2.602 and i
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Daspletosaurus tomsus (MOR 590), an
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2. Freedom of movement inferred fro
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Table 3.2. Surface areas of intemet
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phylogenetic bracketing Wtmer 1995)
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4) Forces from anterior displacerne
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e expected for tyrannosaurid interm
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The preceding discussion derives fr
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weapons sparring), and the arctomet
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Figure 3.1. Schematic representatio
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Figure 3.3. CT reconstruction of ri
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Figure 3.5. MT II (left element) an
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Figure 3.1 1 ae. The metatarsal rec
Page 187: Figure 3.13. Ligament contribution
Page 191 and 192: Figure 3.15. Anatorny of the equid
Page 193: Figure 3.16. Cornparison of loading
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Page 198 and 199: The practicality of the finite elem
Page 200 and 201: collective density of trabeculae (K
Page 202 and 203: A FORCE INPUTS AND MATERIAL PROPERT
Page 204 and 205: Alexander et al. (1 979) rewrded a
Page 206 and 207: The preceding loading regime entait
Page 208 and 209: detemined by using the photographic
Page 210 and 211: 2. Preparation of data for contour
Page 212 and 213: . - Elastic modulus (GP4 Ex EY Ez P
Page 214 and 215: conversion. Volume-to-nuages facili
Page 216 and 217: maintained. An angle of 2 degrees p
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Page 224: Figure 4.1. Initial loads and bound
Page 228: Figure 4.3. Finite element mesh of
Page 232: Figure 4.5. Strain distribution in
Page 236 and 237: CHAPTER 5: Mechanical and evolution
Page 240 and 241: Probable fundion of the tyrannosaur
Page 242 and 243: Ornitholestes, and camosaurs) incre
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Page 248 and 249: face of the skull met part of the m
Page 250 and 251: Alternately, a morphological novelt
Page 252 and 253: outgroup to ail theropods, and the
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Page 262 and 263: Proximal intermetatarsal ligaments
Page 264 and 265: witti a surfeit of potentially supp
Page 267: Figure 5.2. Phylogeny of the Therop
Page 278 and 279: Bock W.J. and von Wahlert G. Evolut
Page 280 and 281: Cume P.J. 1997. Theropoda. In: Fari
Page 282 and 283: Grenard S. 1991. Handbook of Alliga
Page 284 and 285: Liem K.F. and Osse J.W.M. 1975. Bio
Page 286 and 287: Richtsmeier J.T. and Cheverud J.M.
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Woo S., Maynard J., Butler O. 1987.
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Different variables in a PCA will h
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THE UNIVERSITY OF CALGARY Eric Snively A ... - Ohio University

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