Bone deformations in Triassic marine reptiles

The Vossenveld Formation cropping out near Winterswijk in the Netherlands is well known because of its rich Middle Triassic marine reptile fauna assemblage. The aim of the study was to detect and examine bones with unusual shapes in order to identify the causes of their deformation, i.e., taphonomic, traumatic, or related to illness. The unusual, kinked shape of a sauropterygian humerus appears to result from taphonomic processes. Pathological changes were identified on a sauropterygian rib (osteofibrous dysplasia), large bone of uncertain identity (unusual coossification), and on the mandible of cf. Notosaurus marchicus (healed fracture). Despite hundreds of fossilized bones of marine reptiles found in Winterswijk, only few of them preserve pathologies, what may mean that sick or wounded individuals were quickly eliminated from the population.
The illustration shows the eosauropterygian cf. Notosaurus marchicus with mandible which bears signs of healed fracture. Despite the broken jaw, the animal lived on, what is indicated by the fact that the fracture healed. Below, a photograph of the fossilized mandible, the helaed fracture is marked. Illustration by Jakub Zalewski

PUBLICATION: Surmik, D., Szczygielski, T., Słowiak-Morkovina, J., Sander, M., Rothschild, B., Duda, P., & Klein, N. (2023). Bone abnormalities in the middle Anisian marine sauropsids from Winterswijk. Journal of Morphology, 284, e21550. doi:10.1002/jmor.21550