Ichthyopterygia

Ichthyopterygians
Temporal range: Early Triassic - Late Cretaceous, 251.3–90 Ma
Utatsusaurus
Scientific classification
Kingdom:Animalia
Phylum:Chordata
Class:Reptilia
Clade:†Ichthyosauriformes
Superorder:†Ichthyopterygia
Owen, 1840
Subgroups

See text.

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 elongate 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 an advantage 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 By the later part of the Middle Triassic they were extinct, having been replaced by their descendents the true ichthyosaurs.

Taxonomy

Phylogeny

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

Ichthyopterygia

 

 

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

  1. ↑ Motani, R. (1997). "Temporal and spatial distribution of tooth implantation in ichthyosaurs". In J. M. Callaway and E. L. Nicholls (eds.). Ancient Marine Reptiles. Academic Press. pp. 81–103.
  2. ↑ 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.
  3. ↑ Motani, R. (2000). "Rulers of the Jurassic Seas". Scientific American. 283 (6): 52–9. doi:10.1038/scientificamerican1200-52. PMID 11103459.
  4. ↑ 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.

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


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