Ichthyopterygia

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]

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

See text.

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 By the later part of the Middle Triassic, they were extinct, having been replaced by their descendants, the true ichthyosaurs.

TaxonomyEdit

 
Nasorostrans and basal ichthyopterygians

PhylogenyEdit

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

ReferencesEdit

  1. ^ 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.
  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. S2CID 4416186.
  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. S2CID 131501541.

General referencesEdit

External linksEdit