Meeting Abstract
A collection of disassociated caudal vertebrae belonging to two titanosaurian sauropod taxa (Rapetosaurus and Malagasy Taxon B) from the Maevarano Formation of Madagascar record unusual osteopathological lesions. In a survey of 85 caudal vertebral centra from 30+ young juvenile individuals, abnormalities were identified in 46 specimens. Lesions vary in shape and size, and their presence varies in distribution along the tail. They are present on both anterior and posterior vertebral articular surfaces. In some specimens, multiple lesions occur on a single surface. The lesions vary in shape, and can be categorized as curvilinear, linear, pit/divot, C-shaped, T-shaped, or irregular. Lesions are not the result of post-mortem or pre-depositional taphonomic processes such as weathering or breakage: lesion boundaries are clear and complete, and vertebrae are exceptionally well preserved. These lesions are most similar to neontological Schmorl’s nodes, intervertebral disc herniations that penetrate the adjacent vertebral endplate and stimulate bone remodeling. Schmorl’s nodes are commonly recorded in the lumbar region of the human vertebral column due to trauma or repetitive movements that cause the nucleus pulposus of the intervertebral disc to bulge into and reshape the articulating vertebral face. These spinal abnormalities occur under bending or compressive loads, and are more likely to occur with the weakening of the spinal column due to old age. They can be associated with other spinal pathologies such as kyphosis and/or osteoporosis. Currently, there is no consensus on the pathogenesis of Schmorl’s nodes. Their frequent occurrence of this pathology in the titanosaur sample may reflect biomechanical loading in the caudal region, perhaps linked to an unknown behavior in juvenile sauropods.
