Belongs within: Ichthyosauria.
Contains: Merriamosauria.
The Hueneosauria are a clade of ichthyosaurs defined by Maisch & Matzke (2000) as the most exclusive clade including Mixosaurus cornalianus and Ophthalmosaurus icenicus.
Synapomorphies (from Maisch & Matzke 2000): External naris placed largely laterally; anterior margin of orbit regularly rounded; ramus occipitalis of supratemporal well developed; processus transversus pterygoidei absent; posterior dorsal centra discoidal; sacral ribs indistinguishable; caudal vertebral centra short; interclavicle of triradiate shape; radius and ulna distinctly shortened; posterior margin of ulna convex or straight; distal carpals II–IV of similar size; metacarpal V with straight or concave posterior margin or absent; pubis and ischium with strongly convex medial margins, not forming symphysis; less than five toes present.
<==Hueneosauria | i. s.: Guizhouichthyosaurus tangae Cao & Lu in Yin et al. 2000 [incl. Cymbospondylus asiaticus Li & You 2002]JH05 |--+--Wimanius Maisch & Matzke 1998MM03, MM00 | | `--*W. odontopalatus Maisch & Matzke 1998MM00 | `--MixosauridaeJH05 | |--Barracudasaurus Jiang, Hao et al. 2005JH05 | | `--*B. maotaiensis (Young 1965) [=Mixosaurus maotaiensis]JH05 | `--+--Mixosaurus Baur 1887JH05, MM00 [incl. Sangiorgiosaurus Brinkmann 1998MM00] | | |--*M. cornalianus (Bassani 1886)MM00 | | `--M. kuhnschnyderi (Brinkmann 1998)MM00 [=Sangiorgiosaurus kuhnschnyderiH02] | `--PhalarodontinaeJH05 | |--Contectopalatus Maisch & Matzke 1998JH05, MM00 | | `--*C. atavus (Quenstedt 1852)MM00, H02 [=Mixosaurus atavusH02] | `--Phalarodon Merriam 1910JH05, MM00 | |--*P. nordenskioeldii (Hulke 1873)MM00 [=Mixosaurus nordenskioldiH02] | |--P. atavusFF13 | |--P. callawayiFF13 | |--P. fraasiFF13 | `--P. major (von Huene 1916)MM00 `--Longipinnati [Euichthyosauria, Shastasauridae]MM00 |--‘Cymbospondylus’ buchseri Sander 1989FF13, MM00 `--+--CymbospondylidaeMM00 | |--Phantomosaurus Maisch & Matzke 2000MM03, MM00 | | `--*P. neubigi (Sander 1997) [=Shastasaurus neubigi]MM00 | `--Cymbospondylus Leidy 1868FF13, MM00 | |--*C. piscosus Leidy 1868MM00 | |--C. germanicusD07 | |--C. grandisD07 | |--C. natansD07 | |--C. nevadanusD07 | |--C. parvusD07 | |--C. petrinus Leidy 1868MM00 | `--C. piscosusD07 `--+--+--MerriamosauriaMM00 | `--MerriamosaurusMM03 [incl. Rotundopteryx Maisch & Matzke 2000MM03, MM00] | `--M. hulkei (Maisch & Matzke 2000)MM03 [=*Rotundopteryx hulkeiMM00] `--+--Californosaurus Kuhn 1934FF13, MM00 [incl. Delphinosaurus Merriam 1905 (preoc.)MM00] | `--*C. perrini (Merriam 1902)MM00 `--ToretocnemidaeMM00 |--Qianichthyosaurus Li 1999MM03, MM00 | `--*Q. zhoui Li 1999MM00 `--Toretocnemus Merriam 1903FF13, MM00 (see below for synonymy) |--*T. californicus Merriam 1903MM00 `--T. zitteli (Merriam 1903)MM00
Toretocnemus Merriam 1903FF13, MM00 [incl. Leptocheirus Merriam 1903 non Zaddach 1844MM00, Merriamia Boulenger 1904MM00]
*Type species of generic name indicated
References
[D07] Dixon, D. 2007. The Complete Illustrated Encyclopedia of Dinosaurs & Prehistoric Creatures. Hermes House: London.
[FF13] Fröbisch, N. B., J. Fröbisch, P. M. Sander, L. Schmitz & O. Rieppel. 2013. Macropredatory ichthyosaur from the Middle Triassic and the origin of modern trophic networks. Proceedings of the National Academy of Sciences of the USA 110 (4): 1393–1397.
[H02] Haubold, H. 2002. Literaturbericht: Ichthyosaurier und Sauropterygier. Zbl. Geol. Paläont. Teil II 5-6: 367–403.
[JH05] Jiang, D.-Y., W.-C. Hao, M. W. Maisch, A. T. Matzke & Y.-L. Sun. 2005. A basal mixosaurid ichthyosaur from the Middle Triassic of China. Palaeontology 48 (4): 869–882.
[MM00] Maisch, M. W., & A. T. Matzke. 2000. The Ichthyosauria. Stuttgarter Beiträge zur Naturkunde Serie B (Geologie und Paläontologie) 298: 1–159.
[MM03] Maisch, M. W., & A. T. Matzke. 2003. Observations on Triassic ichthyosaurs. Part XII. A new Early Triassic ichthyosaur genus from Spitzbergen. Neues Jahrbuch für Geologie und Paläontologie—Abhandlungen 229 (3): 317–338.