Shonisaurus

Shonisaurus popularis

• North America (Nevada, British Columbia)

Shonisaurus is a Ichthyosauriergattung from the Norian (middle Upper Triassic ) of North America. With lengths of 15 to 21 meters, the genus was one of the largest ichthyosaurs.

Discovery history

The first fossils were discovered in 1928 by Simeon Muller in the U.S. state of Nevada. Under the direction of Charles Camp and Samuel Paul Welles from the University of California, Berkeley began in 1954, the excavations. By 1957, and in other excavations in 1963 and 1965, the close proximity of the remains were recovered of 35 to 40 individuals, none of which were fully intact. 1976, the type species Shonisaurus popularis was described. The archaeological site is now protected as a Berlin- Ichthyosaur State Park. Shonisaurus is the State Fossil of Nevada.

In 1991, the archaeologist Keary Walde discovered on a hike through the forests of British Columbia on the banks of the River Chief Sikanni the fossil remains of a giant beast and reported the discovery to the Royal Tyrrell Museum. The local curator of marine reptiles Elizabeth Nicholls recognized in the fossil a giant ichthyosaur, which had a length of 23 meters, 50 % more than Shonisaurus popularis. The fossil was described as Shonisaurus sikanniensis. It is the largest so far described marine reptile. A similar size probably reached a hitherto undescribed Pliosaur whose fossil remains were known as the Monster of Aramberri.

Features

Shonisaurus had a bulky body with flaring rib cage. S. sikanniensis was slightly slimmer built than S. popularis. The skull of S. popularis was 2.75 meters long, the S. sikanniensis reached a length of three meters. The tail spine was bent down and wore an asymmetrical haiartige fin, in which the larger lobe, however, was lower. The snout was long and was only in the front teeth, adult animals may have had no more teeth. Front and rear fins were the same length, which reached from Shonisaurus popularis a length of 1.5 meters.