Shonisaurus was an ichthyosaur from what is now Nevada. It lived during the late Triassic.
In the 1920s mires found a deposit of huge bones in Nevada. When they were excavated 30 years later they were found to be the remains of 37 individual enormous ichthyosaurs, and were named Shonisaurus. They may have been a shoal that was beached, or cut off from the sea. More recently, the scientific view is that they died and sank to the sea bed.
This ichthyosaur has a whale-like shape and long narrow paddles. It has teeth only at the front of the jaws.
Shonisaurus popularis held the record as the biggest of the ichthyosaurs, but the skeleton of 'an even bigger species, S. sikanniensis was found in the 1990s in British Columbia. With an estimated length of 21 metres (70 ft), this was so big it could only have been seen in its entirety from the air. Recent studies about whether or not S. sikanniensis is a Shonisaurus or an even bigger, closely related ichthyosaur called Shastasaurus have been inconclusive.
- Of the skulls found, only the smaller ones had teeth, Shonisaurus may have become toothless as it grew.