Shonisaurus

Shonisaurus is the largest ichthyosaur, and the largest extinct marine animal that has yet been found. It was found first in rocks of the Upper Triassic in Nevada, and later in British Columbia.
Discovery and description.
Fossils of "Shonisaurus" were first found in a large deposit in Nevada in 1920. Thirty years later, they were excavated, uncovering the remains of 37 very large ichthyosaurs. These were named "Shonisaurus", ("Lizard from the Shoshone Mountains"). "Shonisaurus" lived 216–203 million years ago.
"S. popularis" was about 15 metres (50 ft) long. A longer specimen is now placed in "Shastasaurus" rather than "Shonisaurus". "Shonisaurus" had a long pointed mouth that contained teeth only at the front end. It had a large whale-like body, a long dolphin-like snout, and its flippers were much longer, and narrower than in other ichthyosaurs. All of these features suggest that "Shonisaurus" may be a relatively specialised offshoot of the main ichthyosaur evolutionary line.
Fossils.
The first species discovered, "S. popularis", was adopted as the state fossil of Nevada in 1984. Excavations, begun in 1954 under the direction of Charles Camp and Samuel Welles of the University of California, Berkeley, were continued by Camp throughout the 60s.
The Nevada fossil is at the Berlin–Ichthyosaur State Park, Nevada, USA. The park has several undisturbed ichthyosaur fossils of the species "Shonisaurus popularis" as well as the early-20th Century ghost town of Berlin. The park is about east of Reno.
The discovery of "S. sikkanniensis" in British Columbia in the 1990s made "S. popularis" the smaller of the "Shonisaurus" species. An ichthyosaur found in the Himalayan mountains called "Himalayasaurus", may be the same animal as "Shonisaurus".
British Columbia specimen.
The British Columbia specimen was described as follows:
Life-style.
Its slender skull and lack of teeth except at the front are obvious adaptations to its method of feeding. They are like those of modern whales which feed on squid, such as the pilot whale and sperm whale.