PaleoDB taxon number: 100111
Alternative combinations: Cimoliasaurus snowii, Elasmosaurus snowii
Synonym: Alzadasaurus pembertoni Welles and Bump 1949 (taxon 114170)
Full reference: S. W. Williston. 1890. A new plesiosaur from the Niobrara Cretaceous of Kansas. Transactions of the Kansas Academy of Science 12:174-178
- Styxosaurus snowii: KUVP 1301, a partial skeleton (a skull and 28 cervical vertebrae). Its type locality is Hell Creek, which is in a Campanian marine horizon in the Niobrara Formation of Kansas.
- Alzadasaurus pembertoni: SDSM 451, a skeleton. Its type locality is West bank of Missouri River near Bailey Island, which is in a Campanian/Campanian marine shale/shale in the Pierre Shale Formation of South Dakota.