†Gymocetus Romer 1966 (plesiosaur)
Parent taxon: Plesiosauria according to J. J. Sepkoski 2002
Sister taxa: Aptychodon, Bathyspondylus, Embaphias, Eoplesiosaurus, Eretmosaurus, Hexatarsostinus, Hunosaurus, Iserosaurus, Muraenosauridae, Namuncurania, Neoplesiosauria, Nothosaurops, Orophosaurus, Plesiosauroidea, Pliosauridae, Pliosauroidea, Rhomaleosauridae, Scarrisaurus, Stratesaurus, Sulmosaurus, Taphrosaurus, Tremamesacleididae, Uronautes, Polyptychodon hudsoni, Polyptychodon interruptus
Subtaxa: none
Ecology: aquatic carnivore