Ichthyopterygia ("fish flippers") was a designation introduced by

Sir Richard Owen Sir Richard Owen (20 July 1804 – 18 December 1892) was an English biologist, comparative anatomist and paleontologist. Owen is generally considered to have been an outstanding naturalist with a remarkable gift for interpreting fossils. Ow ...

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 The Triassic ( ) is a geologic period and system (stratigraphy), system which spans 50.6 million years from the end of the Permian Period 251.902 million years ago (Year#Abbreviations yr and ya, Mya), to the beginning of the Jurassic Period 201.36 ...

ancestors. 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

vertebra The spinal column, a defining synapomorphy shared by nearly all vertebrates, Hagfish are believed to have secondarily lost their spinal column is a moderately flexible series of vertebrae (singular vertebra), each constituting a characteristi ...

e, indicating that they swam in a sinuous,

eel Eels are ray-finned fish belonging to the order Anguilliformes (), which consists of eight suborders, 19 families, 111 genera, and about 800 species. Eels undergo considerable development from the early larval stage to the eventual adult stage ...

-like manner. This allowed for quick movements and maneuverability that were advantages in shallow-water hunting. 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 Pangaea or Pangea () was a supercontinent that existed during the late Paleozoic and early Mesozoic eras. It assembled from the earlier continental units of Gondwana, Euramerica and Siberia during the Carboniferous approximately 335 million y ...

, as they are known the Late

Olenekian In the geologic timescale, the Olenekian is an age in the Early Triassic epoch; in chronostratigraphy, it is a stage in the Lower Triassic series. It spans the time between Ma and Ma (million years ago). The Olenekian is sometimes divided i ...

and Early

Anisian In the geologic timescale, the Anisian is the lower stage or earliest age of the Middle Triassic series or epoch and lasted from million years ago until million years ago. The Anisian Age succeeds the Olenekian Age (part of the Lower Triassic ...

(early part of the

period) of Japan, China,

Canada Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world's second-largest country by tot ...

, and Spitsbergen (

Norway Norway, officially the Kingdom of Norway, is a Nordic country in Northern Europe, the mainland territory of which comprises the western and northernmost portion of the Scandinavian Peninsula. The remote Arctic island of Jan Mayen and the ...

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

Taxonomy

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

Phylogeny

Below is a

cladogram A cladogram (from Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an evolutionary tree because it does not show how ancestors are related to ...

modified from Cuthbertson ''et al.'', 2013.

References

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

External links

Ryosuke Motani's detailed Ichthyosaur homepage, with vivid graphics
{{Taxonbar, from=Q2583869 Ichthyosauromorphs Chordate superorders Early Triassic first appearances Turonian extinctions simple:Ichthyopterygia