Shonisaurus

Shonisaurus Temporal range: Norian PreꞒ Ꞓ O S D C P T J K Pg N
Restored skull in a Japanese museum
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Reptilia
Order:	†Ichthyosauria
Family:	†Shastasauridae
Genus:	†Shonisaurus Camp, 1976
Type species
†Shonisaurus popularis Camp, 1976
Species[1][2]
†S. popularis Camp, 1976 †S.? sikanniensis Nicholls and Manabe, 2004

Shonisaurus is a genus of very large

Shonisaurus lived during the late Carnian to Norian stages of the Late Triassic. With a large skull about 2.75 m (9.0 ft) long, S. popularis and measured around 13.5–15 metres (44–49 ft) in length and 21.6–29.7 metric tons (23.8–32.7 short tons) in body mass.^[5][6] S. sikanniensis was one of the largest marine reptiles of all time, measuring 21 metres (69 ft) and weighing 81.5 metric tons (89.8 short tons).^[5]

Shonisaurus had a long snout, and its flippers were much longer and narrower than in other ichthyosaurs. While Shonisaurus was initially reported to have had socketed teeth (rather than teeth set in a groove as in more advanced forms), these were present only at the jaw tips, and only in the very smallest, juvenile specimens. All of these features suggest that Shonisaurus may be a relatively specialised offshoot of the main ichthyosaur evolutionary line.^[7] More recent finds however indicate that Shonisaurus possessed teeth in all ontogenetic stages.^[8] Robust sectorial teeth and gut contents indicate that Shonisaurus was a macrophagous raptorial predator which fed on vertebrates and shelled mollusks like cephalopods, possibly even large-bodied prey.^[9][10] Additionally, Shonisaurus was historically depicted with a rather rotund body, but studies of its body shape since the early 1990s have shown that the body was much more slender than traditionally thought,^[11] and had a relatively deep body compared with related marine reptiles.^[2]

History of discovery

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, which means "lizard from the Shoshone Mountains", after the formation where the fossils were found.

S. popularis, was adopted as the

A second species from the

Specimens belonging to S. sikanniensis have been found in the

• Largest prehistoric organisms
• Shastasaurus, a relative of and what used to be classified as a species of Shonisaurus
• Temnodontosaurus, another large ichthyosaur
• List of ichthyosaurs
• Timeline of ichthyosaur research

Notes