Genus: Ischyrotherium LEIDY, 1856 (nomen dubium)
Etymology:
= Ischyrosaurus COPE, 1870 (non) HULKE, 1874

Species: antiquum LEIDY, 1856
Etymology:
= Ischyrosaurus antiquus (LEIDY, 1856) COPE, 1870

Syntypes: 11559

Locality: Between Moreau River and Grand River, Nebraska.

Horizon: Lignite.

Biostratigraphy:

Age: Cretaceous.

Material: Dorsal vertebrae and 7 rib fragments.

NOTE: possibly a Plesiosaur.