Como Bluff is a long ridge extending east–west, located between the towns of Rock River and Medicine Bow, Wyoming. The ridge is an anticline, formed as a result of compressional geological folding. Three geological formations, the Sundance, the Morrison, and the Cloverly Formations, containing fossil remains from the Late Jurassic of the Mesozoic Era are exposed. Nineteenth-century paleontologists discovered many well-preserved specimens of dinosaurs, as well as mammals, turtles, crocodilians, and fish from the Morrison Formation. Because of this, Como Bluff is considered to be one of the major sites for the early discovery of dinosaur remains. Among the species discovered is the only known specimen of Coelurus. Significant discoveries were made in 22 different areas scattered along the entire length of the ridge. It is included on the National Register of Historic Places as well as the National Natural Landmark list. History of discovery The discovery of dinosaurs at Como Bluff has been recounted numerous times, most notably by Schuchert and LeVene, Shur, Ostrom and McIntosh, and Jaffe. Most of the specimens were collected by men working for O.C. Marsh between 1877 and 1889, although some were collected by the Hubbel brothers for E.D. Cope between 1879 and 1880. The American Museum of Natural History (AMNH) excavated in 1897 -1898 , finding two partial skeletons of sauropods. A summary of the quarries and their contents is given below. In later years, the American Museum of Natural History and Yale University jointly reopened Quarry 9, the Mammal Quarry, 1968–1970, finding only a few specimens. More recently, Robert Bakker has done some collecting there with a variety of groups. In addition to the major significance of dinosaur discoveries at Como Bluff, the site has also been the source of significant early mammal fossils. In early 1878, Marsh was ecstatic to find that one of his men had uncovered a fossil from a Jurassic mammal. Within a year, the historic Quarry 9 at Como was discovered, producing an astounding 250 specimens, which increased the knowledge of Jurassic mammals exponentially. Como Bluff historical quarries (pre-1900) Data source:. . . (h)= holotype AMNH Quarries Excavated by the American Museum of Natural History AMNH Quarry 1 Dinosauria Saurischia Sauropoda Diplodocus sp AMNH Quarry 2 Dinosauria Saurischia Sauropoda Brontosaurus excelsus Camarasaurus sp, AMNH localities unknown (some could be from Quarry 1 or 2) Reptilia Testudines Amphichelydia Glyptops plicatus Squamata ?Sauria indeterminant Lacertilia Paramacellodus sp. Choristodera Cteniogenys