Askeptosauridae is a family of thalattosaurs within the superfamily Askeptosauroidea. Fossils have been found from Italy, Switzerland, and China. Askeptosaurids are distinguished from other thalattosaurs by their long necks and narrow skulls.[1]
Askeptosauridae was named in 1952 to include the genus Askeptosaurus.[2] In 2000, the genus Anshunsaurus, which includes two species, was added to the family.[3] In a 2005 phylogenetic analysis, Endennasaurus was included within Askeptosauridae.[4] Later that year a new study placed Endennasaurus outside Askeptosauridae as a basal member of Askeptosauroidea.[1] More recent studies have placed the genus Miodentosaurus from China in the family as well. Below is a cladogram modified from Wu et al. (2009) showing the phylogenetic relationships of askeptosaurids:[5]