Ogmodirus is an extinct genus of plesiosaur found in the Cenomanian-Turonian (Late Cretaceous) Greenhorn Limestone of Kansas. It may be member of the Elasmosauridae, a group of marine animals related to Elasmosaurus, but the condition of the fossils discovered to date means the genus is dubious beyond Plesiosauria. The type species, O. martini, was named by Samuel Wendell Williston and Roy L. Moodie in 1913. The original specimen consisted of a pelvic girdle, limb elements, and more than fifty cervical (neck) vertebrae discovered in Cloud County, Kansas. A second species, Ogmodirus ischiadicus, has since been referred to Styxosaurus. Sepkoski (2002) assigned Ogmodirus to the Plesiosauria.
Temporal range: Late Cretaceous,
Williston & Moodie, 1913
- Ogmodirus martini from Oceans of Kansas
- Williston, S. W. and Moodie, R. L. (1913). New plesiosaurian genus from the Cretaceous of Nebraska. Bulletin of the Geological Society of America 24: 120-121.
- S. W. Williston. 1903. North American plesiosaurs, part 1. Geological Series Field Museum of Natural History 3(1):1-77
- Sepkoski, J.J. (2002). A compendium of fossil marine animal genera. Bulletins of American Paleontology 363:1-560.