Rhomaleosaurus cramptoni (originally Plesiosaurus Carte and Bailey 1863, Seeley 1874; Early Jurassic, Toarcian, 180 mya; 7m long; NMING F8785) nests basal to Plesiosaurus, the elasmosaurids and pliosaurids in the LRT.

Cryptoclidus eurymerus (Seeley 1892; Middle Jurassic) is a plesiosaur traditionally close to Muraenosaurus, but has not been tested in the LRT.

Muraenosaurus leedsi (Seeley 1874; Middle Jurassic) is a plesiosaur sister to Rhomaleosaurus in the LRT.

Leptocleidus capensis (originally Plesiosaurus capensis, Andrews 1911; Early Cretaceous) nests with Muraenosaurus and Rhomaelosaurus in the LRT. Leptocleidus had a flatter skull, like the latter. These taxa split off before the plesiosaur - pliosaur split.

Tricleidus seeleyi (Andrews 1909; Middle Jurassic, Callovian, BMNH R3539) has a short rostrum and elongate teeth.

Vinialesaurus caroli (Gasparini, Bardet and Iturralde-Vinent 2002; Oxfordian, Late Jurassic, 160my) is a cryptoclidid plesiosaur related to Tricleidus. Two internal nares and two rows of teeth are present.

Andrews CW 1909, 1910. A Descriptive Catalogue of the Marine Reptiles of the Oxford Clay, Part I. British Museum (Natural History), London, England: 205 pp.

Andrews CW 1911. Description of a new plesiosaur (Plesiosaurus capensis sp. nov.) from the Uitenhage beds of Cape Colony. Annals of the South African Museum 1: 309–322.

Carte A, Bailey WH 1863. Description of a new species of Plesiosaurus, from the Lias, near Whitby, Yorkshire. J R Dublin Soc 4:160–170.

Gasparini Z, Bardet N and Iturralde-Vinent M 2002. A new cryptoclidid plesiosaur from the Oxfordian (Late Jurassic) of Cuba. Geobios. 35 (2): 201–211.

Seeley HG 1874. Note on some of the generic modifications of the plesiosaurian pectoral arch. Quarterly Journal of the Geological Society Londong 30:436–449.

Smith AS 2007. Anatomy and systematics of the Rhomaleosauridae (Sauropterygia, Plesiosauria). Ph.D. thesis, University CollegeDublin.

Smith AS and Dyk GJ 2008. The skull of the giant predatory pliosaur Rhomaleosaurus cramptoni: implications for plesiosaur phylogenetics. Naturwissenschaften. 95: 975–980. doi:10.1007/s00114-008-0402-

wiki/Rhomaleosaurus
wiki/Muraenosaurus
wiki/Cryptoclidus
wiki/Leptocleidus
wiki/Tricleidus
wiki/Vinialesaurus