early 20th century. C. lentus was the third of the four currently recognized valid species of Camarasaurus to be named. The holotype was later mounted for display at the Peabody Museum in 1930. In 1909, the Carnegie Museum of Natural History paleontologist Earl Douglass discovered a rich fossil site in Utah, which became protected as part of Dinosaur National Monument in 1915. Excacations at the site lead to the discovery of much additional C. lentus material. A nearly complete specimen of a juvenile C. lentus, CM 11338, was also found at the site by Douglass in 1909, and described by Charles W. Gilmore in 1925. It is the most complete sauropod fossil ever discovered, and nearly every element was in articulation. Later in 1918, the Carnegie Museum collected another complete and articulated skeleton of an adult (USNM V 13786) of C. lentus that was later transferred to the National Museum of Natural History in 1934. The skeleton is now mounted in the NMNH fossil hall. In 1919, the Carnegie Museum's director William Jacob Holland named a new species, Uintasaurus douglassi, on the basis of several cervical vertebrae from the quarry; this species was synonymized with C. lentus in 1958. In 1950, another specimen consisting of an anterior dorsal vertebra from Dinosaur National Monument was named as a new species, Camarasaurus annae; this too is now regarded as synonymous with C. lentus. Additional specimens of C. lentus were discovered by the Wyoming Dinosaur Center in 1992, and are among the most complete adult specimens of the species. Fossils Fossils of Camarasaurus lentus are found in the Morrison Formation. Though most specimens of Camarasaurus cannot be identified to species, C. lentus is the most abundant among specimens that can; 11.1% of Camarasaurus specimens have been assigned to C. lentus. It is among the most well-known sauropod species, with exceptionally complete remains, including the aforementioned CM 11338. Two of the fourteen known sauropod specimens to preserve complete necks belong to C. lentus, and the holotype of C. lentus has a nearly complete neck as well. Most Camarasaurus specimens from Dinosaur National Monument have been referred to C. lentus. The "Wall of Bones" at the Quarry Visitor Center includes specimens of C. lentus still preserved in the rock. A mostly complete but undescribed specimen of C. lentus from Dinosaur National Monument is displayed at the Smithsonian. Classification As a species of Camarasaurus, C. lentus