SVP 2019
Conference Abstract: BISHOP, Peter J., Royal Veterinary College, Hatfield, United Kingdom; CUFF, Andrew, Royal Veterinary College, Hatfield, United Kingdom; MICHEL, Krijn, Royal Veterinary College, Hatfield, United Kingdom; KERMODE, Louise, Royal Veterinary College, Hatfield, United Kingdom; HUTCHINSON, John R., Royal Veterinary College, Hatfield, United Kingdom
ENGAGING AND EXCITING PRE-UNIVERSITY STUDENTS IN STEM VIA 3D MODELLING OF DINOSAUR ANATOMY AND BIOMECHANICS
Category: Taxon: Reptiles, Taxon Subcategory: Archosauria, Geological Era: Not applicable, Topic: Education and Outreach, Presentation Preference: Education & Outreach Poster Session, but if not possible, consider for a Regular Poster Session
Dinosaur palaeontology is well-known for its capability to engage students of all ages, and provides a strong basis for increasing understanding and interest in STEM (Science, Technology, Engineering, and Mathematics) topics. Likewise, three-dimensional digital and physical modelling appeals to students for its visually intuitive and technological aspects, and it can convey a wide variety of concepts of varying degrees of complexity. Combining these approaches can help maximize the scope and impact of STEM outreach work. Here we present a multi-faceted, multi-disciplinary approach that we have refined in local secondary schools with substantial numbers of underrepresented demographics. This approach spans the full breadth of our current research into archosaurian evolutionary biomechanics, using this diversity of topics to reach students with different interests. Our school-based “dinosaur club” sessions run across a series of consecutive weeks, and cover: (1) Triassic–Jurassic palaeontology, ecosystems, macroevolution and extinction; (2) osteology and limb proportions; (3) joint morphology, muscular anatomy and mechanical advantage; (4) body dimensions and computer models of centre of mass and (5) dynamic computer simulations of locomotor balance. Here we explain our approach, the rationale behind each topic covered, and the lessons we have learned from testing it with students. In particular, we have found that framing lessons in the context of group-based games can help inspire interest in concepts and topics that some students may otherwise find abstract or uninteresting, such as Earth history and Newtonian mechanics. Our approach introduces students to major concepts in morphology, showing how morphology is central to the study of organisms, biomechanics, behaviour, ecosystems and evolution, as well as how it can be fascinating in its own right.
Grant Information: Supported by an ERC Horizon 2020 Advanced Investigator Grant (695517, to JRH)
SVP 2019
Conference Abstract: BISHOP, Peter J., Royal Veterinary College, Hatfield, United Kingdom; FALISSE, Antoine, KU Leuven, Leuven, Belgium; DE GROOTE, Friedl, KU Leuven, Leuven, Belgium; HUTCHINSON, John R., Royal Veterinary College, Hatfield, United Kingdom
USING DYNAMIC OPTIMIZATION TO SIMULATE LOCOMOTION IN EXTANT AND EXTINCT ARCHOSAURS
Category: Taxon: Reptiles, Taxon Subcategory: Archosauria, Geological Era: Not applicable, Topic: Function/Mechanics, Presentation Preference: Oral Presentation Preferred
Archosaurs have displayed a wide array of locomotor habits throughout their 250 million year evolutionary history, including quadrupedal and bipedal terrestrial species, semiaquatic and marine forms, and two instances of powered flight. Understanding their history of locomotor specialization and innovation may therefore provide important insight into the patterns and processes of archosaur evolution. Computational biomechanical models of the musculoskeletal system provide a unique avenue to understand, simulate and recreate locomotion in extant and extinct archosaur species. In particular, in silico predictive simulations can explore musculoskeletal function and organismal performance under a range of conditions, beyond those that are measurable in experimental settings, enabling investigation of ‘what if’ questions. Under the assumption that a given behaviour maximizes some performance objective, dynamic optimization can be used to generate simulations of behaviours de novo, including maximal performance behaviours. Here, we explore the ability of direct collocation approaches to generating various maximum performance simulations in the fastest extant terrestrial archosaur, the ostrich. Direct collocation approximates the system dynamics over a series of short time intervals, obviating the need for explicit numerical integration, and the states (e.g., limb kinematics) and controls (e.g., muscle activations) throughout the entire behaviour are optimized simultaneously. By avoiding forward integration, the optimization problem can be solved very quickly using standard computing hardware. We have conducted simulations for running, walking and vertical jumping with an 18 degree-of-freedom, 68 muscle model, and these can generally be solved in under an hour. Our running simulation reaches a maximum speed of 15 m/s, comparable to that reported for wild ostriches. However, we have found that simulation performance and results are highly sensitive to how well ‘tuned’ the musculotendon parameters are, suggesting that certain simplifications may be necessary, particularly for modelling extinct species, such as using an ideal muscle model (i.e., independent of length or velocity effects) over the more traditional Hill-type model. Framed with circumspect caution and suitable sensitivity analysis, direct collocation dynamic optimization has great promise in enabling simulation of locomotor behaviours in extinct archosaurs.
Grant Information: Supported by an ERC Horizon 2020 Advanced Investigator Grant (695517, to JRH)
SVP 2019
Conference Abstract Andrew Cuff, Alejandro Otero, John R. Hutchinson
FUNCTIONAL DISPARITY IN TRIASSIC JURASSIC ARCHOSAUR HINDLIMBS, AND IMPLICATIONS FOR MUSCULOSKELETAL MODELLING
The late Triassic to early Jurassic was a time of high terrestrial diversity and disparity in archosaurian reptiles, initially with the pseudosuchians and then dinosauromorphs. However, the modern diversity of archosaurs is restricted to crocodilians and birds. Here we investigated the functional disparity of archosaur hindlimbs, widely seen as remarkable, using biomechanics. Skeletal models of fossil and extant species of pseudosuchians (Batrachotomus, Poposaurus and Nile crocodile) and dinosauromorphs (Marasuchus,
Lesothosaurus, Coelophysis, Mussaurus, and elegant-crested tinamou) were digitized, and muscles added to these models in musculoskeletal modelling software. We then calculated ranges of motions (ROM) and normalized muscle moment arms of the hip, knee, and ankle. Pseudosuchian taxa generally had the greatest ROM in hip flexion/extension, whilst dinosauromorphs had the greatest ankle extension (due absence of the enlarged calcaneal tuber). Across the other joints, ROM was similar between the taxa. Muscle moment arms varied widely depending on the method of size-normalization. When the cube root of body mass was used, smaller taxa had larger moment arms around most joint axes. When scaled against femoral length, Mussaurus had the largest hip flexion/extension moment arms for the M. caudofemoralis longus, but the smallest for M. flexor tibialis externus. Extinct pseudosuchians had some of the largest M. gastrocnemius moment arms, as expected from the calcaneal tuber; and comparable to birds. Hence there is a tradeoff in ankle mobility and leverage in archosaurs. The fossil taxa and crocodile retained ancestral hip abduction/adduction moment arms, contrasting to the patterns in birds. By using 3D musculoskeletal models we can explicitly quantify functional disparity in (and evolution of) archosaurian hindlimb function, and we discovered important lessons about tradeoffs between different methods of normalizing muscle moment arms.
Funding: European Research Council Horizon 2020 Advanced Investigator Grant 695517.
SVP 2019
Conference Abstract: Oliver E. Demuth1,2,*, Emily J. Rayfield2 & John R. Hutchinson1 1Structure & Motion Laboratory, Royal Veterinary College, Hatfield, AL9 7TA, UK, 2School of Earth Sciences, University of Bristol, Bristol, BS8 1RJ, UK * odemuth@rvc.ac.uk
3D LIMB BIOMECHANICS OF THE STEM-ARCHOSAUR EUPARKERIA CAPENSIS
Archosaurs are a diverse group of reptiles, originating shortly before the Triassic period and radiating rapidly after the Permo-Triassic mass extinction event. In the Triassic they explored disparate morphologies in the pelvis and ankle, which led to different locomotor types and body plans throughout their evolutionary history. The diverse skeletal morphologies in Triassic archosauriforms had an undeniable influence on their locomotion, however the implications for specific functions are still poorly understood. Early archosaurs and sister taxa to Archosauria are essential to understand the evolution of the different locomotor adaptations; however, quantitative locomotor biomechanics studies of extinct archosaurs have so far focused almost exclusively on non-avian dinosaurs. Here, we present the first detailed, quantitative and 3D investigation into the locomotory abilities of the Middle Triassic stem-archosaur Euparkeria capensis. Micro-computed tomography scans of multiple specimens from South Africa enabled the reconstruction of the limbs of Euparkeria in unprecedented detail and the characterization of previously unknown morphological features. A composite pelvic girdle and hindlimb were created to accommodate for any missing or only partially preserved elements and/or taphonomic distortion. The bones of the individual specimens were scaled isometrically to match those of the holotype. To test previous qualitative hypotheses regarding posture, gait and stance of Euparkeria, the mobility of the hindlimb was assessed by quantifying the maximal joint ranges of motion (ROM) in 3D. Two sensitivity analyses were performed to account for the unknown amount of epiphyseal cartilage and the restricting influence of soft-tissue. Due to the medially expanded femoral head and the distinct supra-acetabular rim, Euparkeria seems to have been capable of adopting a more crocodile-like “semi-erect” posture, which is further supported by our ROM analysis. The femur could be fully adducted and the feet positioned underneath the body. This is consistent with other evidence suggesting that the common ancestor of archosaurs had a similar ability to adduct the hindlimbs into less sprawling poses. However, hip (and hence limb) abduction remained feasible, so more sprawling poses were not excluded by our analysis — the hip was quite mobile. Further analyses including moment arms of muscles across the ROM are enabled by this new dataset, and with more taxa we could better reconstruct the evolution of limb function in Archosauria in the future.
ICVM 2019
Conference Abstract: Prof John Hutchinson
Getting pre-university students excited about STEM via 3D modelling of dinosaur anatomy in teaching, J.R. Hutchinson1, P.J. Bishop1, A. R. Cuff1, L. Kermode1, K. Michel1. 1Structure and Motion Laboratory, Department of Comparative Biomedical Sciences, Royal Veterinary College, Hatfield, United Kingdom
Dinosaur palaeontology is famous for exciting students of many ages and for providing leverage to get them more interested in STEM topics. Three-dimensional computer (and physical) modelling is likewise appealing to students for its visually intuitive and technological natures, and yet can convey a wide variety of concepts of varying degrees of complexity. Thus it is popular to combine these approaches in educational and outreach work. Here we present a multi-pronged, multi-disciplinary approach that we have been refining in local schools with substantial numbers of underrepresented students. This approach spans the full breadth of our current archosaurian evolutionary biomechanics research (https://www.dawndinos.com), using the diversity of topics to reach students with different interests. Our school-based “dinosaur club” sessions cover: (1) Triassic-Jurassic palaeontology, ecosystems, macroevolution and extinction; (2) Osteology and limb proportions; (3) Joint morphology and mechanical advantage; (4) Body dimensions and computer models of centre of mass and (5) Dynamic computer simulations of locomotor balance. Here we explain our approach and lessons learned from testing it with students, plus comparisons/contrasts with similar club sessions run with students whose major interest is art rather than science. We then expound upon how our approach also introduces students to major concepts in morphology, showing how morphology is central to the study of organisms, biomechanics, behaviour, ecosystems and evolution, as well as fascinating in its own right.
ICVM 2019
Conference Abstract P.J. Bishop1, A. Falisse2, J.W. Rankin3, F. De Groote2 and J.R. Hutchinson1.
1Structure and Motion Laboratory, Comparative Biomedical Sciences, Royal Veterinary College, Hatfield, United Kingdom. 2Department of Movement Sciences, KU Leuven, Leuven, Belgium. 3Pathokinesiology Laboratory, Rancho Los Amigos National Rehabilitation Center, Downey, USA.
Slips, trips, and computer chips: the promises and pitfalls of dynamic optimization of locomotion simulations
Computational models can offer unique insights into musculoskeletal function. For instance, simulations based on models can provide information on aspects not easily measurable from experiments alone. However, simulations that track experimental data are limited to what was measured in vivo, which may not represent natural conditions or an organism’s maximum capabilities. In contrast, in silico predictive simulations can explore musculoskeletal function under any range of conditions, enabling investigation of ‘what if’ questions. Under the assumption that a given behaviour maximizes some performance objective, dynamic ptimization can be used to generate simulations of behaviours de novo, including maximal
performance behaviours. Here, we explore the ability of two dynamic optimization approaches – shooting and direct collocation – to generate various maximum performance simulations in the fastest terrestrial biped, the ostrich. In shooting, the model’s initial states and control history (e.g. muscle excitations) are optimized. However, this approach is computationally expensive (sometimes requiring supercomputers) as it involves forward numerical integration of highly nonlinear system dynamic equations, which furthermore can make the problem very sensitive to the initial conditions. In direct collocation, the system
dynamic equations are approximated by Lagrange polynomials over short time intervals, obviating the need for forward integration, and the states and controls throughout the entire behaviour are optimized simultaneously. By avoiding forward integration, the optimization problem can be solved orders of magnitudes more quickly, e.g. our 18 degree-of-freedom ostrich model could be solved on a single laptop core in <10 minutes. We present comparisons between the two approaches for simulations of walking, running and jumping, demonstrating that direct collocation offers a powerful, accessible framework for simulating locomotor biomechanics in vertebrates.
The Society for Integrative and Comparative Biology (SICB), Annual Conference 2019
Conference Abstract: Dr Krijn Michel
Sunday, Jan. 6 15:30 – 17:30 A comparison of appendicular muscle physiology and biomechanics in Archosauria MICHEL, K B*; WEST, T G; DALEY, M A; ALLEN, V; HUTCHINSON, J R; Royal Vet College, London; Royal Vet College, London; Royal Vet College, London; Royal Vet College, London; Royal Vet College, London kmichel@rvc.ac.uk
Archosaurian reptiles (including living crocodiles and birds) have had an explosion of locomotor variation since the Triassic. Their appendicular muscle physiology and biomechanics are pivotal to our understanding of how their diversity, natural history and evolution relate to this locomotor variation. Information on muscle contraction velocity, force and power in extinct archosaurs such as Pseudosuchia and Ornithodira is of course not available from fossil material, but is needed for biomechanical modelling and simulation. However, an approximation or range of potential parameter values can be obtained by studying extant representatives of the archosaur lineage. Here, we perform a quantitative study of the physiological performance of multiple muscles from several individuals of Nile crocodile (Crocodylus niloticus) and Elegant crested tinamou (Eudromia elegans). Nile crocodile musculature shows high power and velocity values– the FTI4, a small “hamstring” hip extensor and knee flexor actively used for terrestrial locomotion, performs particularly well. The Elegant crested tinamou muscles’ performance is on par with birds of similar body mass, and shows the same pattern of parameter variation between muscles of a similar function in other birds. These findings demonstrate physiological differences between anatomical muscles, potentially based on their roles during locomotion. By contributing new data from previously unstudied archosaurian species and muscles to existing data, we can now better bracket possible muscle parameter values, and thereby better estimate in computational analyses how extinct archosaurs may have moved.
Conference Abstract: Prof John Hutchinson
Sunday, Jan. 6 15:30 – 17:30 Electromyographic Analysis Of Appendicular Muscle Function In Extant Archosaurs CUFF, AR; DALEY, MA; MICHEL, KB; ALLEN, VR; LAMAS, LP; ADAMI, C; MONTICELLI, P; PELLIGAND, L; HUTCHINSON, JR*; Royal Veterinary College; Royal Veterinary College; Royal Veterinary College; Royal Veterinary College; Royal Veterinary College; Royal Veterinary College; Royal Veterinary College; Royal Veterinary College; Royal Veterinary College jhutchinson@rvc.ac.uk http://www.dawndinos.com
Archosauria (birds, crocodiles and all descendants of their common ancestor) is characterized by remarkable locomotor variation across its evolution since the Triassic. More sprawling, quadrupedal crocodiles and more erect, bipedal birds are prime examples of this variation. The functional implications of musculoskeletal anatomy have been widely studied, but more experimental data are needed on how muscles control locomotor movements in extant archosaurs. We present new electromyographic measurements from key appendicular muscles across a range of walking and running speeds in Nile crocodiles and numerous species of birds (tinamous, emus, guinea fowl, pheasants, turkeys and quail). We consider how extant archosaurs control limb movements, and how neuromotor control has likely evolved. Crocodiles, like most other tetrapods, use their pectoral muscles in an antigravity role. Crocodiles’ iliotibial, digital flexor and gastrocnemius muscles are activated similarly to birds (including Palaeognathae); likely ancestral for Archosauria. Birds, regardless of clade or ontogenetic status, show conservatism among the hindlimb muscles studied; these motor patterns appear ancestral for Aves. Our analysis is important for revealing which muscles display neuromotor conservation vs. evolutionary specialization. These findings are vital for testing the validity of computer simulations and reconstructing how locomotor disparity evolved in Archosauria.
PalAss 2019
Conference Abstract: Oliver E. Demuth1,2,*, Emily J. Rayfield2 & John R. Hutchinson1 1Structure & Motion Laboratory, Royal Veterinary College, Hatfield, AL9 7TA, UK 2School of Earth Sciences, University of Bristol, Bristol, BS8 1RJ, UK * odemuth@rvc.ac.uk
3D LIMB BIOMECHANICS OF THE STEM-ARCHOSAUR EUPARKERIA CAPENSIS
Triassic archosaurs and stem-archosaurs show remarkable disparity in their ankle and pelvis morphologies leading to functional diversity. However the implications of these different morphologies for locomotion have never been quantitatively assessed. Here, we present a novel quantitative analysis of the locomotory abilities of a stem-archosaur, applying 3D modelling techniques. μCT scans of multiple specimens of Euparkeria capensis enabled the reconstruction and three-dimensional articulation of the ankle, pelvis and pectoral girdle in unprecedented detail and the discovery of previously unknown morphological features in this taxon. The maximal joint mobility of the hind- and forelimb were quantified in 3D to address previous qualitative hypotheses regarding posture, gait and stance of Euparkeria. The range of motion analysis supports an erect posture indicated by the hip morphology, as the femur and humerus could be fully adducted to position the feet beneath the body. However, more sprawling poses could not be excluded and hip abduction remained feasible. The oblique mesotarsal ankle joint in Euparkeria implies a more abducted hindlimb and reveals seemingly contradicting morphological characters. The posture of archosaurs appears to have evolved in complex mosaic-like fashion and cannot be determined by relying solely on morphological characters.
dawndinos.com 