The sauropod body plan presents a unique set of challenges for a living organism due to the extreme body size and hyperelongation of the neck and tail. The neck and tail were held clear of the ground, with the weight of the extremity being transferred proximally into the body. The sauropod vertebral column therefore needed to withstand very large stresses at all times. The column also had to provide for an adequate range of motion for the animals' routine behavior, such as feeding, defense, and mating. We can predict that these biomechanical demands and the attendant compromises should be reflected in distinct morphological specializations of the vertebrae. My research focuses on describing these specializations and testing hypotheses for how different morphologies influenced the stabillity and flexibility of the sauropod vertebral column.

Cervical vertebra (C9) of the sauropod Diplodocus carnegii in left lateral view showing
opisthocoelous articulation type (Hatcher, 1901)

One example of a vertebral specialization in sauropods is the presence of concavo-convex articulations between cervical vertebrae, loosely comparable to ball-and-socket joints. Sauropod cervical vertebrae are almost invariably opisthocoelous, having a convex anterior articulation and a concave posterior articulation. My work seeks to explain the functional advantage(s) that led to the early evolution of this trait and its retention for at least 135 Ma of sauropod evolution. A variety of hypotheses are being tested using experimental models as well as comparative anatomical approaches. In addition, variation in articular morphology is being described serially within the individual vertebral column and across sauropod clades. The objective of this survey is to understand what different vertebral articular morphologies indicate about the biomechanical demands, behavioral capabilities, and ecology of disparate sauropod taxa.

This work also has implications for many taxa besides sauropods. Although the particular arrangment of concavo-convex joints in sauropods is distinctive, many other vertebrates utilize similar structures in the vertebral column under a wide range of structural conditions. Concavo-convex joints are also characteristic of the appendicular skeleton, albeit under even more dissimilar biomechanical demands. Any insight gained into the function of such joints in one taxon has the potential to illuminate more general rules governing joint morphology. In time, it may be possible to explain and predict the distribution of different types of concavo-convex joints both anatomically and phylogenetically.