Basal ichthyosaurs

Chaohusaurus geishanensis (Young and Dong 1972) Early Triassic, was a small primitive ichthyosaur with huge eyes and a large flipper, but finger phalanges not transformed into discs. Above as traced from specimen AGM CHS-5. Below from Motani et al. 2014 with embryos in color.

Parvinatator wapitiensis (Nicholls and Brinkman 1995) Early to Middle Triassic was a primitive ichthyosaur, with a deep skull and phalanges in the process of transition to discs.

Phalarodon atavus (Liu et al. 2013) is a little Middle Triassic ichthyosaur close to mixosaurs.

Ichthyosaurus pectoral and pelvic girdles.

Grippia longirostris (Wiman 1929) was another primitive ichthyosaur, but with a shorter rostrum and no teeth.

Besanosaurus leptorhynchus (Dal Sasso and Pinna 1996, Middle Triassic, 240-210 mya) was a large ichthyosaur with a small head and pointed flippers. Gray bones are hyoids.

Qianichthyosaurus zhoui (Li 1999, Nicholls et al. 2002, Late Triassic, ) had a long rostrum and very tall head housing a large eyeball. The lateral temporal fenestra was lost. This is a late-surviving basal ichthyosaur.

Mixosaurus (Baur 1887, Middle Triassic, 240-210 mya) was a small to medium (up to 6 feet long) ichthyosaur with a rather straight tail and a dorsal fin.

Cymbospondylus grandis (Leidy 1868, Middle Triassic, 240-210 mya) was a giant (20-33 ft long) primitive ichthyosaur with a long, wumengosaur/mesosaur-like body.

Family tree of the Ichthyosauria listed chronologically with most taxa present in the Triassic from Motani (1999).

Family tree of the Ichthyosauria using only those taxa currently present in the large reptile tree.

Dal Sasso C and Pinna G 1996. Besanosaurus leptorhynchus n. gen. n. sp., a new shastasaurid ichthyosaur from the Middle Triassic of Besano (Lombardy, N. Italy). Paleontologia Lombardia 4:23 pp.

Jiang D-Y, Rieppel O, Motani R, Hao W-C, Sun Y-I, Schmitz L and Sun Z-Y. 2008. A new middle Triassic eosauropterygian (Reptilia, Sauropterygia) from southwestern China. Journal of Vertebrate Paleontology 28:1055–1062.

Leidy J 1868. Notice of some reptilian remains from Nevada: Proceedings of the American Philosophical Society 20:177-178.

Liu J et al 2013. The first specimen of the Middle Triassic Phalarodon atavus (Ichthyosauria: Mixosauridae) from South China, showing postcranial anatomy and per–Tethyan distribution. Palaeontology 56:849-866.

Maisch MW 2010. Phylogeny, systematics, and origin of the Ichthyosauria - the state of the art. Palaeodiversity 3: 151-214.

Motani R, You H and McGowan C 1997. Eel-like swimming in the earliest ichthyosaurs. Nature, 382:347–348.

Motani R, Minoura N and Ando T 1998. Ichthyosaur relationships illuminated by new primitive skeletons from Japan. Nature, 393:255–257.

Motani R 1999. Phylogeny of the Ichthyopterygia. Journal of Vertebrate Paleontology 19(3):473-496.'

Nicholls EL and Brinkman DB 1995. A new ichthyosaur from the Triassic of Sulphur Mountain Formation of British Columbia. Pp 521-535 in Sargent WAS (ed) Vertbrate Fossils and the Evolution of Scientific Concepts. Gordon and Breach, Switzerland.

Nicholls EL , Wei C and Manabe M 2002. New material of Qianichthyosaurus Li, 1999 (Reptilia, Ichthyosauria) from the Late Triassic of southern China, and implications for the distribution of Triassic ichthyosaurs. Journal of Vertebrate Paleontology 22:759-765.

Shikama T, Kamei T and Murata M 1978. Early Triassic ichthyosaurs, Utatsusaurus hataii gen. et sp. nov., from the Kitakami Massif, Northwest Japan. Science Report of the Tohoku University Sendai, Japan, second series (Geology), 48: 77–97.

Wiman C 1929. Eine neue Reptilien-Ordnung aus der Trias Spitzbergens. Bulletin of the Geological Institutions of the University of Upsala 22: 183–196.

Wu X-C, Cheng Y-N, Li C, Zhao L-J and Sato T 2011. New Information on Wumengosaurus delicatomandibularis Jiang et al., 2008, (Diapsida: Sauropterygia), with a Revision of the Osteology and Phylogeny of the Taxon. Journal of Vertebrate Paleontology 31(1):70–83.

Young CC and Dong ZM 1972. On the aquatic reptiles of the Triassic in China. Vertebrate Paleontology Memoire 9:1-34

wiki/Utatsusaurus

Marine Younginiformes

Enaliosauria

Mesosauria

Ichthyopterygia

Thaisaurus • Xinminosaurus