The Systematics and Evolution of Middle-Late Jurassic Sauropod Dinosaurs from China, and Macroevolutionary Trends in Saurischian Vertebral Regionalization, Shape, and Pneumaticity

Sauropod dinosaurs are among the most diverse and abundant members of Mesozoic vertebrate faunas and are iconic for their massive sizes and exceptionally long, pneumatic (i.e., air-filled) necks. Sauropods from the Middle-Late Jurassic of China were the first to evolve necks greater than nine meters in length, yet their anatomy remains poorly documented in the literature, and few studies have rigorously assessed their evolutionary relationships. The goal of this dissertation was to comprehensively detail the anatomy and revise the systematics of two poorly-studied sauropod dinosaurs from the Middle-Late Jurassic Shishugou Formation of northwest China and to use extant birds as a study system within which to test hypotheses concerning the evolution of the saurischian axial skeleton. First, I describe the cranial anatomy of the enigmatic sauropod Bellusaurus sui and critically review sauropod cranial ontogeny, furnishing new hypotheses of ontogenetic trends that can be tested by future discoveries of juvenile specimens. Second, I detail the anatomy of Klamelisaurus gobiensis, and use parsimony and time-calibrated Bayesian phylogenetic methods to demonstrate that it is a member of a mostly-Chinese lineage of long-necked sauropods. Anatomical comparisons with several other sauropods and data from myological studies of extant archosaurs provide new insights on the identification and homology of sauropod cervical muscle scars. Third, I use phylogenetically-informed Bayesian comparative methods to identify region- and clade-specific scaling relationships in the axial skeleton of extant birds, demonstrating that variation in vertebral number is an important but under-appreciated component of body size evolution. Finally, I use high-fidelity micro-computed tomography scans and geometric morphometric methods to show that extent of pneumaticity is highly correlated with vertebral shape across the axial skeleton in extant storks, providing support for the hypothesis that extent of vertebral pneumatization is a function of the biomechanical regime acting on a vertebra.

Author

• Moore, Andrew

Language

• English

Keyword

• Vertebrae
• Pneumaticity
• Bayesian phylogenetics
• Geometric morphometrics
• Sauropod dinosaurs
• Ontogeny

Date created

• 2018

Type of Work

• Dissertation

License

• All rights reserved

Rights statement

• In Copyright

GW Unit

• Biological Sciences

Degree

• Ph.D.

Advisor

• Clark, James M

Committee Member(s)

• Carrano, Matthew T
• Forster, Catherine A
• Hernandez, L. Patricia
• Pyron, R. Alexander

Persistent URL

•  https://scholarspace.library.gwu.edu/etd/8336h290s