Shonisaurus – Giant of the Ichthyosauria

Team members at Everything Dinosaur received an email the other day with a request for more information on giant ichthyosaurs.  There were certainly a number of very large members of the ichthyosaur family.  The Ichthyosauria are a very diverse Order, evolving in the Early Triassic and surviving for over 140 million years before becoming extinct shortly before the end of the Cretaceous Period.   There is the giant Cymbospondylus (pronounced Sim-bow-spon-die-lus), fossils of which have been found in North America and Europe.  This gigantic marine reptile had a large body, an eel-like tail, a metre long head with large jaws.  Cymbospondylus is the biggest marine reptile known from Late Triassic strata.


Perhaps our favourite large ichthyosaur is Shonisaurus (Shonisaurus popularis), a marine reptile that may reached lengths in excess of fifteen metres.  The first fossils of this ichthyosaur were found by miners around the now deserted mining town of Berlin, Nevada in North America.  The fossils were so plentiful that miners used them to decorate their dwellings and some of the large, flat vertebrae were even used as dinner plates!  Reports of these fossils had been made from as early as 1869 but the miners were too busy digging for gold and silver to worry.

Shonisaurus popularis is the largest ichthyosaur to have been discovered to date in the United States and was believed to be the biggest in the world until fossils of a new species of ichthyosaur over 23 metres long were unearthed in Canada just a few years ago.

A Scale Drawing of Shonisaurus popularis


Giant ichthyosaur of the Late Triassic and Early Jurassic. Picture credit: Everything Dinosaur.

Picture credit: Everything Dinosaur

This ichthyosaur had a very deep body, and four, long, narrow equally sized flippers.  Teeth were present only in the front of the jaw.  This animal probably hunted cephalopods – ammonites, belemnites, squid and octopi.

For models and replicas of giant marine reptiles including ichthyosaurs: Models of Sea Monsters.

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