Ichthyopterygia

Superregnum: Eukaryota
Cladus: Unikonta
Cladus: Opisthokonta
Cladus: Holozoa
Regnum: Animalia
Subregnum: Eumetazoa
Cladus: Bilateria
Cladus: Nephrozoa
Superphylum: Deuterostomia
Phylum: Chordata
Subphylum: Vertebrata
Infraphylum: Gnathostomata
Megaclassis: Osteichthyes
Cladus: Sarcopterygii
Cladus: Rhipidistia
Cladus: Tetrapodomorpha
Cladus: Eotetrapodiformes
Cladus: Elpistostegalia
Superclassis: Tetrapoda
Cladus: Reptiliomorpha
Cladus: Amniota
Classis: Reptilia
Cladus: Eureptilia
Cladus: Romeriida
Subclassis: Diapsida
Superordo: †Ichthyopterygia
Ordo: Ichthyosauria - Incertae Sedis
Name

Ichthyopterygia Owen, 1840
Vernacular names
中文: 魚龍超目

Ichthyopterygia ("fish flippers") was a designation introduced by Sir Richard Owen in 1840 to designate the Jurassic ichthyosaurs that were known at the time, but the term is now used more often for both true Ichthyosauria and their more primitive early and middle Triassic ancestors.[1][2]

Basal ichthyopterygians (prior to and ancestral to true Ichthyosauria) were mostly small (a meter or less in length) with elongated bodies and long, spool-shaped vertebrae, indicating that they swam in a sinuous, eel-like manner. This allowed for quick movements and maneuverability that were advantages in shallow-water hunting.[3] Even at this early stage, they were already very specialised animals with proper flippers, and would have been incapable of movement on land.

These animals seem to have been widely distributed around the coast of the northern half of Pangea, as they are known the Late Olenekian and Early Anisian (early part of the Triassic period) of Japan, China, Canada, and Spitsbergen (Norway). By the later part of the Middle Triassic, they were extinct, having been replaced by their descendants, the true ichthyosaurs.

Taxonomy
Nasorostrans and basal ichthyopterygians

Superorder Ichthyopterygia
? Genus Isfjordosaurus
? Family Omphalosauridae
Family Parvinatatoridae
Family Thaisauridae
Family Utatsusauridae
Eoichthyosauria
Order Grippidia
Order Ichthyosauria

Phylogeny

Below is a cladogram modified from Cuthbertson et al., 2013.[4]

Ihthyopterygia

Parvinatator wapitiensis     Utatsusaurus hataii         Xinminosaurus catactes   Eoichthyosauria Grippidia   Grippia longirostris     Gulosaurus helmi     Ichthyosauria sensu Motani (1999)   Chaohusaurus geishanensis       Cymbospondylus     Mixosauria   Mixosaurus cornalianus     Phalarodon atavus       Toretocnemidae   Qianichthyosaurus zhoui     Toretocnemus californicus       Shastasauria   Shonisaurus popularis       Shastasaurus pacificus     Callawayia neoscapularis           Guizhouichthyosaurus tangae       Besanosaurus leptorhynchus       Californosaurus perrini     Parvipelvia

 
 
 
References

Motani, R. (1997). "Temporal and spatial distribution of tooth implantation in ichthyosaurs". In J. M. Callaway; E. L. Nicholls (eds.). Ancient Marine Reptiles. Academic Press. pp. 81–103.
Motani, R.; Minoura, N.; Ando, T. (1998). "Ichthyosaurian relationships illuminated by new primitive skeletons from Japan". Nature. 393 (6682): 255–257. doi:10.1038/30473. S2CID 4416186.
Motani, R. (2000). "Rulers of the Jurassic Seas". Scientific American. 283 (6): 52–9. doi:10.1038/scientificamerican1200-52. PMID 11103459.

Cuthbertson, R. S.; Russell, A. P.; Anderson, J. S. (2013). "Cranial morphology and relationships of a new grippidian (Ichthyopterygia) from the Vega-Phroso Siltstone Member (Lower Triassic) of British Columbia, Canada". Journal of Vertebrate Paleontology. 33 (4): 831. doi:10.1080/02724634.2013.755989. S2CID 131501541.

General references

Ellis, Richard, (2003) Sea Dragons - Predators of the Prehistoric Oceans. University Press of Kansas
McGowan, C & Motani, R. (2003) Ichthyopterygia, Handbook of Paleoherpetology, Part 8, Verlag Dr. Friedrich Pfeil