diarthroossetes
Diarthroossetes is a taxonomic term that has been used in the past to describe a group of extinct marine reptiles. The name itself is derived from Greek words meaning "freely articulating joints," referring to certain skeletal features observed in these creatures. Historically, diarthroossetes was often associated with the ichthyosaurs, a diverse order of marine reptiles that lived during the Mesozoic Era. Some early classifications recognized diarthroossetes as a distinct order or suborder within the larger group of marine reptiles, or sometimes as a synonym for ichthyosaurs themselves.
However, modern paleontological understanding has largely superseded the use of diarthroossetes as a formal taxonomic rank.