Ichthyosaur

Shonisaurus popularis is Nevada's official state fossil, first designated in 1977 and amended in 1988. It was a massive ichthyosaur — a dolphin-shaped marine reptile — that swam a deep ocean covering what is now central Nevada during the Late Triassic period. Nevada holds one of the most important ichthyosaur sites in the world: Berlin-Ichthyosaur State Park, where 37 specimens lie exposed in the rock where they died about 225 million years ago.

Shonisaurus popularis reached up to 50 feet in length, making it one of the largest ichthyosaurs known and one of the biggest animals of the Triassic period. It had a long, narrow body, four broad paddle-like flippers, and a tall dorsal fin. Its skull was elongated with a toothless beak in adults — unusual among ichthyosaurs, which typically had teeth.

Like all ichthyosaurs, Shonisaurus was an air-breathing reptile that spent its entire life in the ocean. It gave birth to live young at sea rather than laying eggs on land. It hunted in a deep-water environment, likely pursuing soft-bodied cephalopods and fish. Shonisaurus and its relatives died out at the end of the Triassic period, about 200 million years ago.

The Berlin site was known from the early 20th century, but the ichthyosaur bones were not formally studied until the 1950s when University of California, Berkeley paleontologist Charles Camp led excavations that exposed multiple skeletons in the same area. Camp formally described the species as Shonisaurus popularis in 1976, naming it after the Shoshone Mountains where the fossils were found.

Nevada designated Shonisaurus popularis as its state fossil just one year later in 1977, reflecting how quickly the scientific and public significance of the Berlin site was recognized. The designation was amended in 1988 to update the official wording. Berlin-Ichthyosaur State Park opened to protect the site, and a shelter was built over the main quarry so visitors can walk among the exposed bones.

Berlin-Ichthyosaur State Park in Nye County is the only public site where Shonisaurus popularis fossils can be seen in situ. The park's fossil shelter covers a quarry floor holding the partial skeletons of 37 individuals, exposed at the surface of the Late Triassic Luning Formation. The site is about 23 miles east of the town of Gabbs in a remote stretch of the central Nevada desert.

The concentration of so many large animals in one place is unusual and still debated by scientists. Some researchers suggest the ichthyosaurs beached themselves on a shallow bank; others propose a mass stranding or a toxic algae event. No single explanation has been confirmed.