Thalassiodracon hawkinsi (originally Plesiosaurus Owen 1838; Storrs and Taylor 1996; up to 2m in length; Late Triassic, 200 mya; BMNH 2018) nests with Yunguisaurus here. This specimen retains an interclavicle, lost in later genera. The orbit is larger than in other plesiosaurs.

Yunguisaurus liae (Cheng et al. 2006; Sato et al. 2016; Late Triassic; NMNS 004529/F003862), is a new pistosaurid, a transitional taxon between nothosaurs and plesiosaurs.

Cheng Y-N, Sato T, Wu -C and Li C 2006. First complete pistosauroid from the Triassic of China. Journal of Vertebrate Paleontology 26 (2): 501–504.

Owen R 1865. A monograph on the fossil Reptilia of the Liassic Formations. Part 3. Sauropterygia. Monograph of the Palaeontographical Society 17: 1-40

Sato T, Zhao L-J, Wu X-C and Li C 2013. A new specimen of the Triassic pistosauroid Yunguisaurus, with implications for the origin of Plesiosauria (Reptilia, Sauropterygia). Palaeontology. Article first published online: 7 MAY 2013 DOI: 10.1111/pala.12048

Storrs GW and Taylor MA 1996. Cranial anatomy of a new plesiosaur genus from the lowermost Lias (Rhaetian/Hettangian) of Street, Somerset, England. Jour. Vert. Paleo. 16:403-20.

wiki/Yunguisaurus
wiki/Thalassiodracon