|1st Species||Shastasaurus pacificus|
|2nd Species||Shastasaurus alexandrae|
|3rd Species||Shastasaurus sikanniensis|
|Time Range||235-205.6 mya|
|Location||United States of America, Canada|
|Name Meaning||Mount Shasta reptile|
|Physical Dimensions||8.3 meters long for S.alexandrae; 19.6 meters long for S.sikanniensis|
|Weight||30.9 tonnes for S.sikanniensis|
Shastasaurus is a shastasaurid ichthyosaurian reptile from the Late Triassic of the United States of America and Canada. It was named in 1895 by John Campbell Merriam. It was the biggest ichthyosaur to swim the prehistoric seas, and by extension, the biggest marine reptile of all time.
Shastasaurus was relatively unique for an ichthyosaur. It had an elongated and streamlined body, 4 flippers, a long tail with a fluke on its end, and a conical head with large, toothless jaws. Its body would have been covered in scaly skin.
Shastasaurus was a predator, preying on fish and cephalopods. Its teeth were small yet sharp, and were used to get a hold of slippery prey.
Unlike other Triassic ichthyosaurs (like Cymbospondylus), Shastasaurus did not have any teeth on its jaws; in fact, even the juveniles had toothless jaws. However, it made up for this with its hunting strategy: it lunged at large schools of small fish or cephalopods with its mouth open, creating a small vacuum that sucked water particles and prey items into its mouth; this would have been useful when dealing with cephalopods, as they are able to propel themselves forward with jets of water. One species of Shastasaurus, Shastasaurus sikanniensis, reached 19.6 meters in length and weighed 30.9 tonnes, and would have been impervious to predation. As well as this, due to its increased dimensions, it would have been able to collect more air than other marine reptiles, as well as hold its breath for a longer time; therefore, it would have been able to dive deeper into the depths of the Triassic oceans.