Shonisaurus

Shonisaurus is an extinct genus of giant ichthyosaurs from the Late Triassic. Its fossils are known chiefly from Nevada and British Columbia.

Shonisaurus popularis: A species of Shonisaurus known from Late Triassic fossils in Nevada. The Nevada species anchors the genus’s best-known fossil assemblage.
Ichthyosaur: An extinct group of marine reptiles adapted to life in the Mesozoic seas. Shonisaurus belongs to this marine-reptile group.
Ichthyosaur locomotion: The modes of swimming used by ichthyosaurs, involving body, tail, and fin movement. Shonisaurus’s streamlined body and tail relate to propulsion through water.
Shastasaurus: An extinct genus of large ichthyosaurs from the Triassic. It is a close comparison for Shonisaurus among giant Triassic ichthyosaurs.
Ichthyosaur taxonomy: The classification of ichthyosaurs based on anatomy, fossils, and evolutionary relationships. Taxonomic revisions affect which fossils belong in Shonisaurus.
Shonisaurus sikanniensis: A species of Shonisaurus described from Late Triassic fossils in British Columbia. Its Canadian remains extend the genus beyond Nevada.
Triassic: The first period of the Mesozoic Era, lasting from about 252 to 201 million years ago. Shonisaurus lived during the Triassic, before the Jurassic radiation of many marine reptiles.
Caudal fin: A tail fin that generates thrust or helps steer aquatic animals. The tail anatomy helps explain how Shonisaurus propelled its large body.
Ichthyosauria: The clade comprising ichthyosaurs and their closest relatives. The broader clade frames Shonisaurus’s evolutionary placement.
Ichthyosaur body size: Methods and estimates used to determine the size of fossil ichthyosaurs. Shonisaurus size estimates depend on incomplete skeletons and scaling assumptions.

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TemnodontosaurusCompared with: Its later and much larger forms contrast with Temnodontosaurus's Early Jurassic history.