Genus: Marshosaurus MADSEN, 1976
Etymology: After Othniel Charles Marsh, a great student of dinosaurs.

Species: bicentesimus MADSEN, 1976
Etymology: In honor of the bicentennial of the United States.

Holotype: UUVP 2826

Locality: Cleveland-Llyod Dinosaur Quarry, approximately 20 miles south of Price, SE 1/4, SE 1/4, Sec. 21, T17S, R11E, SLBM. lat 39°19’00", Long. 110°41’15"W, San Rafael Swell Area, Carbon County, Utah.

Horizon: Brushy Basin Member, Morrison Formation.

Biostratigraphy: Zone 3.

Age: Comobluffian age, Kimmeridgian Stage, uppermost Malm Epoch, Late Jurassic.

Material: Left ilium.
Note: Palaeopathology an anomalous ridge on the lateral face, thought to be the result of an injury (MOLNAR, 2001).