original_query: What is the significance of the pleurapophyses in plesiosaurs?
query: What is the significance of the pleurapophyses in Elasmosaurus?
answer: The pleurapophyses' significance in Elasmosaurus (and potentially other plesiosaurs) relates to the narrow breadth of the vertebra between them, a feature initially noted in *Plesiosaurus constrictus* (later considered *Elasmosaurus constrictus*).  This narrowness was considered a natural condition, not just a preservation artifact, and  might be a characteristic of some elasmosaurids.