1 of the Dominguez/Jones Quarry, near the confluence of the Little Dominguez Creek and the Big Dominguez Creek. They warned James A. Jensen, the preparator of the Brigham Young University who collected the find. The specimen was found in the Brushy Basin Member of the Morrison Formation, in Mesa County, Colorado. Jensen named and described it as a new genus and species, Cathetosaurus lewisi, in 1988. The genus name means "perpendicular lizard" (from ), in reference to Jensen's hypothesis that the animal was adept at rearing onto its hind legs. The specific name honors Jensen's mentor Arnold David Lewis, the preparator of the Harvard Museum of Natural History. Classification When Jensen first named C. lewisi, he assigned it to a new genus of camarasaurid, Cathetosaurus. In 1996, John S. McIntosh and colleagues synonymized Cathetosaurus with Camarasaurus, noting that most of the differences proposed by Jensen pertained to the maturity of the specimen, but retained C. lewisi as a distinct species; this assignment was followed by later reviews of sauropod taxonomy. In 2005, Takehito Ikejiri noted that C. lewisi did not clearly differ from C. grandis, with which it was contemporary, and therefore may be synonymous with it. Two unpublished studies, presented at the 2013 and 2014 annual meetings of the Society of Vertebrate Paleontology by Octávio Mateus and Emanuel Tschopp, reevaluated the taxonomy of Camarasaurus and concluded that Cathetosaurus should be regarded as a separate genus from Camarasaurus after all, though subsequent papers by Tschopp have included C. lewisi within Camarasaurus without comment, or expressed uncertainty over whether C. lewisi belonged to Camarasaurus or Cathetosaurus. In 2017, Cary Woodruff and John Foster argued that most of the putative distinguishing traits of C. lewisi were indicative of old age, suggesting that C. lewisi may be based on an old individual of another Camarasaurus species. Most researchers consider C. lewisi to be one of the four valid species of Camarasaurus. Specimens The holotype and only definite specimen of C. lewisi is BYU 9047, a mostly complete specimen representing an old individual. It consists of a partial skeleton lacking the skull, the still present occiput probably not having been collected due its poor quality. It contains the vertebral column from the first neck vertebra onwards to the forty-third tail vertebra; neck ribs; twenty dorsal ribs; twenty-six chevrons; the right forelimb; the left pelvis and the right ischium. According to Michael P. Taylor, as