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 n 1931.

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.