Evolution of sauropod dinosaur postcranial biomechanics: a virtual paleontology approach

• Autores: Daniel Vidal Calés
• Directores de la Tesis: José Luis Sanz García (dir. tes.), Francisco Javier Ortega Coloma (dir. tes.)
• Lectura: En la UNED. Universidad Nacional de Educación a Distancia ( España ) en 2019
• Idioma: español
• Tribunal Calificador de la Tesis: Luis Alcalá Martínez (presid.), Fernando Escaso Santos (secret.), Paul Sereno (voc.)
• Programa de doctorado: Programa de Doctorado en Ciencias por la Universidad Nacional de Educación a Distancia
• Materias:
  • Ciencias de la vida
    • Paleontología
      • Paleontología de los vertebrados
• Enlaces
  • Tesis en acceso abierto en: hdl.handle.net
• Resumen

  • Sauropod dinosaurs are the largest known terrestrial vertebrates. Their characteristic body plan, quadrupeds with columnar limbs, long necks and tails, is unique among terrestrial vertebrates, and it is likely key in understanding their evolution. However, due to the fragmentary nature of the known fossil record and the difficult manipulation of their fossils (fragile, enormous and heavy in many cases), their functional morphology and motion capabilities are still relatively poorly known. Recently, the advent of 3D technology and its progressive cheapening has allowed studying the subject better than ever before.

    The main goal developed in this PhD dissertation is to generate a virtual model for an early branching eusauropod using virtual paleontology techniques with the exceptionally complete and well-preserved holotypic skeleton of Spinophorosaurus nigerensis (Jurassic of Niger). Among these techniques are (i) reconstructing its body plan by articulating the skeleton in a virtual environment; (ii) assessing its osteological range of motion on axial and appendicular skeleton; (iii) reconstructing the origins and insertions of the principal muscle groups; and (iv) estimating muscle lines of action and volumes. The results have been used to assess the functional capabilities of this sauropod, to compare the same techniques applied to extant vertebraes, and to compare the results with virtual skeletons of more fragmentary sauropods representing most well-established clades.

    These analyses show that wedging of the sacrum has a key role in determining the osteologically induced curvature of the vertebral spine in all Eusauropoda (which includes most known sauropods). This finding changes the skeletal reconstructions and the interpretation of the body plan of a large number of sauropods. This has direct implications in the estimated biomechanical capabilities of these sauropods, some of them even evolving in covariation with the sacrum wedging as a functional module related to feeding strategies. Something similar occurs with the locomotor module, particularly with the pelvic girdle, femora and caudal vertebrae: throughout sauropod evolution, the osteological correlates for caudal, ischial and posterior iliac musculature become gradually more reduced while the anterior iliac musculature became more enlarged and the pelvis widened. This is explained by changes in locomotion toward less propulsion coming from femoral retraction. Both modules, however, did not evolve suddenly, but in mosaic, as is common with other functional modules in Dinosauria.

    The result of applying virtual paleontology techniques to extant vertebrates reveal that these techniques can estimate correctly their actual posture and ranges of motion with no need for factors other than actual skeletal anatomy. This makes conclusions regarding sauropod taxa more robust, since it implies an independent line of evidence for testing the biomechanical capabilities of fossil vertebrates.