Meet the Mount Shasta Lizard: The Largest Known Marine Reptile to Ever Live on Earth

In 1893, Stanford University’s James Perrin Smith went of a fossil-collecting expedition to Northern California’s Triassic Hosselkus Limestone in the areas between Squaw Creek and the Pit River. He returned with the bones of a marine reptile that he believed to be a Nothosaurus, but in the decade following they would conclude it was a new species – the largest marine reptile ever known to have lived on Earth.

Thus, the Shastasaurus was discovered, aptly named after the nearby Mount Shasta.

The Shastasaurus, also known as the Mount Shasta Lizard, lived on earth about 210 million years ago, during the Triassic period, and could grow to be 75 feet long. While dinosaurs roamed the land, this marine reptile ruled the ocean in an odd way, using its short, toothless snout as a very strong suction feeder, consuming primarily on soft-bodied cephalapods in the ocean.

The Shastasaurus was long and slender, with its ribcage measuring in at 6 feet wide despite being 23 feet long. The creature’s characteristics and habits are still up for debate in the scientific community, but we know one thing about the Shastasaurus – it was massive.

Since its discovery in the late-1800s, the Shastasaurus has grown to be a well-known genus of ichthyosaur found around the world. Scientists have since realized that two other ichthyosaurs – one in China and another in Canada – were also a part of the Shastasaurus family.

As scientists and paleontologists continue to gather information and classify these animals from millions of years ago, there’s still a lot of questions as to what led to the Shastasaurus’s demise. But one thing is for sure, the largest marine reptile once called Northern California its home.