NOT Guizhouichthyosaurus (Jiang et al. 2020; XNGM-WS-50-R4; Middle Triassic; 240 mya) This 5m specimen includes an embryo, originally considered to be a partial thalattosaur as a recent meal. Notably both have longer proximal limb elements and shorter digits, especially in the manus. This specimen nests closer to Shonisaurus than Guizhouichthyosaurus.

Shonisaurus popularis (Camp 1976, Kosch 1990; 15m, 49 feet long, Late Triassic, Carnian) known from 37 incomplete fossils, Shonisaurus was a large ichthyosaur, but surprisingly not related to the even larger specimen TMP 94.378.4 assigned by Nicholls and Matanabe (2004) to Shonisaurus sikanniensis which is related to Cymbospondylus. They have distinct skull and pectoral morphologies.

Camp CL 1976. Vorläufige Mitteilungüber grosse Ichthyosaurier aus der oberen Trias von Nevada. Österreichische Akademie der Wissenschaften, Mathematisch-Naturwissenschaftliche Klasse, Sitzungsberichte, Abteilung I 185:125-134.

Camp CL 1981. Child of the rocks - The story of the Berlin-Ichthyosaur State Park. Nevada Bureau of Mines and Geology, Special Publication 5, 36 pp.

Jiang D-Y et al. (7 co-authors) 2020. Evidence supporting predation of 4-m marine reptile by Triassic megapredator. online

Kosch, BF 1990. A revision of the skeletal reconstruction of Shonisaurus popularis (Reptilia: Ichthyosauria). Journal of Vertebrate Paleontology 10 (4): 512.

wiki/Shonisaurus