Genus: Parrosaurus GILMORE, 1945 (nomen dubium)
Etymology: In honor of Albert Eide Parr. American zoologist and then director of the American Museum of Natural History, and Greek, sauros, “lizard”: “Parr’s lizard”.
= Neosaurus GILMORE, vide GILMORE & STEWART, 1945 non NOPCSA, 1923 (Neosaurus cynodus, Pelycosauria, Sphenacodontidae, incertae sedis)
= Parrasaurus WHITE, 1973 (sic)

Species: missouriense (GILMORE vide GILMORE & STEWART, 1945) GILMORE, 1945 (nomen dubium)
Etymology: In reference to the state of Missouri, where the specimen was discovered.
= Neosaurus missouriensis GILMORE vide GILMORE & STEWART, 1945) (nomen dubium)
= Hypsibema missouriensis (GILMORE & STEWART, 1945) BAIRD & HORNER, 1979 (nomen dubium)

Holotype: USNM 16735

Locality: Chronister farm, sec. 26, T31N, R9E, about 1 mile north of Glen Allen, Bollinger County, Missouri.

Horizon: McNairy Sand Member, Ripley Formation.

Biostratigraphy: Middle Mosasaurus Acme-zone.

Age: Uppermiddle Navesinkan Age, Lower Maastrichtian Stage, Upper Senonian Subepoch, Upper Gulf Epoch, Late Cretaceous.

Material: 13 caudal centra, a fragment of left maxilla and a fragment of a predentary.