Enigmatic plesiosaur taxa

Opallionectes andamookaensis (meaning "the opal swimmer from Andamooka") is the name given to a 5 m (16 ft) long cryptoclidian plesiosaur, which is thought to have lived during the early Cretaceous period (Lower middle Aptian), 115 million years ago, in shallow seas covering what is now Australia.

Bathyspondylus is an extinct genus of plesiosaur from the Kimmeridge Clay Formation of Swindon, England. Because it is known only from its fossil vertebrae (and so few of those have been recovered), paleontologists are not entirely sure of the taxonomy of Bathyspondylus; the family it belongs to is not currently known. The type, and only known, species is B. swindoniensis, which was described from the same material as its genus.

Leurospondylus is an extinct genus of plesiosaur from the Horseshoe Canyon Formation of Canada whose family is currently disputed, but is suggested to be Elasmosauridae.