Genus: Plesioelasmosaurus SCHUMACHER & EVERHART, 2022
Etymology: Greek, Plesio, "near to", Greek, elasmos, "metal plate" and and Greek, saurus, "lizard." As in a basal representative of the family Elasmosauridae.

Species: walkeri SCHUMACHER & EVERHART, 2022
Etymology: In honor of Myrl V. Walker (1903-1985) for his lifetime of contributions to teaching, paleontology, and conservation of geologic resources on federal lands (see Rogers, 1988). Walker collected the holotype speicmen along with George F. Sternberg in 1931.
=Elasmosauridae incertae sedis SCHUMACHER & EVERHART, 2005.

Holotype: USNM 50134 (originally USNM 1195, listed as USNM 50135, USNM 50136 in Everhart 2007).

Locality: Approximately 2 miles west of the town of Holyrood, Wllsworth County, Kansas.

Horizon: Basal Lincoln Limestone Member, Greenhorn Limestone.

Biostratigraphy:

Age: Middle Cenomanian Stage, Late Gallic Subepoch, Early Gulf Epoch, Middle Cretaceous.

Material: 2 teeth, 12 cervical vertebrae, 3 'pectoral' vertebrae, 3 dorsal vertebrae, 3 or 4 sacral vertebrae, portions of ~25 caudal vertebrae, numerous portions of ribs and gastralia, both ilia, nearly complete right fore and hind paddles, partial left hind paddle and more than 200 gastroliths.