Utatsusaurus
genus of reptiles / From Wikipedia, the free encyclopedia
Utatsusaurus is the earliest-known form of an ichthyopterygian. It lived in the earliest Lower Triassic period, about 250–245 millions years ago. It is nearly 3m (about 9 feet) long with a slender body.[1]
Utatsusaurus | |
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Fossil | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Reptilia |
Superorder: | †Ichthyopterygia |
Family: | †Utatsusauridae McGowan & Motani, 2003 |
Genus: | †Utatsusaurus Shikama et al., 1978 |
Type species | |
†Utatsusaurus hataii Shikama et al., 1978 |
The name Utatsusaurus was given after the city Utatsu-cho where the first specimen was found.[2] The fossils have been found in the Lower Triassic of Miyagi Prefecture, Japan and British Columbia, Canada.[3]
Utatsusaurus is one of the most primitive (basal) types of ichthyosaur.[4][5] It has transitional features between its ancestral land-dwelling forms and the more derived ichthyosaurs. Unlike the more advanced ichthyosaurs, Utatsusaurus has no dorsal fin and has a broad skull. The snout gently tapers, compared to the more rounded one of more derived ichthyopterygians.[6] The tail had a long low fin, quite different from the tail shape of later forms. This suggests that the animal swam by undulation, waving its body to & fro, rather than using its paddles and tail.
The 2011 Tōhoku earthquake and tsunami destroyed the local museum, but fortunately the specimens were not there at the time.