Who was elasmosaurus related to?

Elasmosaurus was a genus of plesiOSaur, a group of marine reptiles that thrived during the Late Cretaceous period. It is closely related to other members of the PlesiOSauria clade, which includes both long-necked forms like Elasmosaurus and shorter-necked varieties. PlesiOSaurs are part of the broader group of diapsids, which also includes modern reptiles like crocodiles and birds. Elasmosaurus specifically is known for its extremely long neck, comprising a significant portion of its total length.