Styxosaurus
Styxosaurus is a genus of plesiosaur of the family Elasmosauridae. Styxosaurus lived during the Campanian age of the Cretaceous period. Two species are known: S. snowii and S. browni.
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 a large elasmosaur with a 5.25 metres (17.2 ft) long neck.[1][2] It reached 10.5 metres (34 ft) in length and 2.3 metric tons (2.5 short tons) in body mass.[3] Its sharp teeth were conical and were adapted to puncture and hold rather than to cut; like other plesiosaurs, Styxosaurus swallowed its food whole.[4]
The holotype specimen of Styxosaurus snowii was described by S.W. Williston[5][6] from a complete skull and 20 vertebrae.[5]
Another more complete specimen - SDSMT 451 (about 11 metres (36 ft) long) was discovered near Iona, South Dakota, also in the US, 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.[1] 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.[7]
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."
