''Ogmodirus'' is an extinct

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial n ...

of plesiosaur found in the Cenomanian-

Turonian The Turonian is, in the ICS' geologic timescale, the second age in the Late Cretaceous Epoch, or a stage in the Upper Cretaceous Series. It spans the time between 93.9 ± 0.8 Ma and 89.8 ± 1 Ma (million years ago). The Turonian is preceded ...

(

Late Cretaceous The Late Cretaceous (100.5–66 Ma) is the younger of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''creta'', ...

)

Greenhorn Limestone The Greenhorn Limestone or Greenhorn Formation is a geologic formation in the Great Plains Region of the United States, dating to the Cenomanian and Turonian ages of the Late Cretaceous period. The formation gives its name to the Greenhorn cyc ...

Kansas Kansas () is a state in the Midwestern United States. Its capital is Topeka, and its largest city is Wichita. Kansas is a landlocked state bordered by Nebraska to the north; Missouri to the east; Oklahoma to the south; and Colorado to ...

. The

type species In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specimen( ...

, ''O. martini'', was named by

Samuel Wendell Williston Samuel Wendell Williston (July 10, 1852 – August 30, 1918) was an American educator, entomologist, and paleontologist who was the first to propose that birds developed flight cursorially (by running), rather than arboreally (by leaping from ...

and

Roy Lee Moodie Roy is a masculine given name and a family surname with varied origin. In Anglo-Norman language, Anglo-Norman England, the name derived from the Norman language, Norman ''roy'', meaning "king", while its Old French cognate, ''rey'' or ''roy'' ...

in 1913.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.

Discovery and naming

The holotype, KUVP 441, consists of a pelvic girdle, limb elements, and more than fifty cervical (neck)

vertebrae The spinal column, a defining synapomorphy shared by nearly all vertebrates, Hagfish are believed to have secondarily lost their spinal column is a moderately flexible series of vertebrae (singular vertebra), each constituting a characteristi ...

from a juvenile discovered in

Cloud County, Kansas Cloud County (county code CD) is a county located in the U.S. state of Kansas. As of the 2020 census, the county population was 9,032. Its county seat and most populous city is Concordia. History Early history For many millennia, the Gre ...

by C. Boyce in 1909. KUVP 441 was named as ''Ogmodirus martini'' by Williston & Moodie (1913) and the species name was amended to ''martinii'' by Moodie (1916), but the original name takes precedence. The holotype was described in detail by Williston & Moodie (1917).S. W. Williston and R. L. Moodie. (1917). ''Ogmodirus martinii'', a new plesiosaur from the Cretaceous of Wyoming. ''The University of Kansas Science Bulletin'' 10(2):61-73 A second species, ''Ogmodirus ischiadicus'' (based on specimen KUVP 434), was initially placed within its own genus, ''Thalassiosaurus'', and has since been referred to ''

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''. Description ''Styxosaurus'' was a large p ...

''. It was placed in ''Ogmodirus'' by Willison & Moodie (1917).

Classification

According to Welles (1962),S. P. Welles. (1962). A new species of elasmosaur from the Aptian of Colombia and a review of the Cretaceous plesiosaurs. ''University of California Publications in Geological Sciences'' 44(1):1-96 ''Ogmodirus martini'' may be member of the

Elasmosauridae Elasmosauridae is an extinct family of plesiosaurs, often called elasmosaurs. They had the longest necks of the plesiosaurs and existed from the Hauterivian to the Maastrichtian stages of the Cretaceous, and represented one of the two groups ...

, a group of marine animals related to ''

Elasmosaurus ''Elasmosaurus'' (;) is a genus of plesiosaur that lived in North America during the Campanian stage of the Late Cretaceous period, about 80.5million years ago. The first specimen was discovered in 1867 near Fort Wallace, Kansas, US, and was se ...

'', but the condition of the fossils discovered to date means the genus is

dubious Doubt is a mental state in which the mind remains suspended between two or more contradictory propositions, unable to be certain of any of them. Doubt on an emotional level is indecision between belief and disbelief. It may involve uncertainty ...

beyond Plesiosauria. Sepkoski (2002) assigned ''Ogmodirus'' to the

Plesiosauria The Plesiosauria (; Greek: πλησίος, ''plesios'', meaning "near to" and ''sauros'', meaning "lizard") or plesiosaurs are an order or clade of extinct Mesozoic marine reptiles, belonging to the Sauropterygia. Plesiosaurs first appeared ...

.Sepkoski, J.J. (2002). A compendium of fossil marine animal genera. ''Bulletins of American Paleontology'' 363:1-560.

References

{{Taxonbar, from=Q7080135 Late Cretaceous plesiosaurs of North America Cretaceous reptiles of North America Elasmosaurids Plesiosaurs of North America Fossil taxa described in 1913 Taxa named by Samuel Wendell Williston Sauropterygian genera

Discovery and naming

Classification

See also

References