Kingdom Animalia
Phylum Chordata
Superclass Tetrapoda
Class Reptilia
Subclass Diapsida
Order Ichthyosauria
Family Shastasauridae
Genus Shastasaurus
1st Species Shastasaurus pacificus
2nd Species Shastasaurus alexandrae
3rd Species Shastasaurus sikanniensis
Other attributes
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
Dietary Classification Carnivore

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.

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