Thalassonomosaurus
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Styxosaurus Temporal range: Late Cretaceous, 83.5–80.5 Ma |
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| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Reptilia |
| Superorder: | †Sauropterygia |
| Order: | †Plesiosauria |
| Family: |
†Elasmosauridae Welles, 1943 |
| Genus: |
†Styxosaurus (Williston, 1890) [originally Cimoliasaurus] |
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Styxosaurus is a genus of plesiosaur of the family Elasmosauridae. Styxosaurus lived during the Santonian and Campanian ages of the Cretaceous period.
Styxosaurus was a large plesiosaur, one of several species of a group collectively called elasmosaurs that appeared in the Late Cretaceous. Elasmosaurs typically have a neck that is at least half the length of the body, and composed of 60-72 vertebrae.
Styxosaurus was around 11–12 metres (36–39 ft) long, with about half of the length being composed of its 5.25 metres (17.2 ft) neck. Its sharp teeth were conical and were adapted to puncture and hold rather than to cut; like other plesiosaurs, Styxosaurus swallowed its food whole.
The holotype specimen of Styxosaurus snowii was described by S.W. Williston from a complete skull and 20 vertebrae.
Another more complete specimen - SDSMT 451 (about 11 metres (36 ft) long) was discovered near Iona, South Dakota, also in the USA, in 1945. The specimen was originally described and named Alzadasaurus pembertoni by Welles and Bump (1949) and remained so until it was synonymized with S. snowii by Carpenter. Its chest cavity contained about 250 gastroliths, or "stomach stones". Although it is mounted at the School of Mines as if its head were looking up and out of the water, such a position would be physically impossible.
Styxosaurus is named for the mythological River Styx (Στυξ), which separated the Greek underworld from the world of the living. The -saurus part comes from the Greek sauros (σαυρος), meaning "lizard" or "reptile."
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Wikipedia