the Kellaways Formation below the Oxford Clay where most specimens were derived from. Hulke described a found in 1868 by J.C. Mansel in the Kimmeridge Clay in 1869, considering it a large saurian possibly related to Cetiosaurus or Pelorosaurus. He then gave it the name Ischyrosaurus in 1874, reiterating its close relationship to Cetiosaurus oxoniensis, Cetiosaurus humerocristatus, and Gigantosaurus. Though it was not given a species name at the time, Richard Lydekker identified it as the species Ornithopsis manseli in 1887 based on an unpublished manuscript name provided by Hulke, as well as describing additional Wealden material as O. hulkei, and suggesting Cetiosaurus humerocristatus was a synonym of O. leedsii. Cetiosaurus oxoniensis was reassigned to Ornithopsis as O. oxoniensis in 1888 by Harry Govier Seeley, a proposal that was not endorsed at the time by Lydekker, who also suggested that O. leedsii and O. humerocristatus were possibly distinct based on a difference in age, but that Chondrosteosaurus and Ornithopsis eucamerotus were synonyms of O. hulkei. Ornithopsis leedsii was referred to as the species Pelorosaurus leedsi by Lydekker in 1895, and as the taxon Cetiosaurus leedsi by Arthur Smith Woodward in the 1905, which are incorrect spellings of the species name. Cetiosaurus leedsii (spelled as "leedsi") had additional remains referred to it by Woodward in 1905, including the anterior caudal vertebrae BMNH R1984, the distal caudals BMNH R1967, and the posterior skeleton BMNH R3078, which preserved most of the arm, leg, pelvis, and vertebrae behind the shoulders. They species was assigned to Cetiosaurus as the vertebrae were differently textured, so Woodward considered an assignment to Cetiosaurus more proper. Friedrich von Huene did not think the referral of the species to Cetiosaurus should be supported, and referred to the taxon as "Cetiosaurus" leedsi. Huene also described the species Ornithopsis (?) greppini in the same study in 1921, for a long-tailed cetiosaurid from Jurassic deposits around Bern, Switzerland. Huene retained O. greppini in the genus in an early 1927 review of sauropods, considering the genus to contain the species Ornithopsis hulkei, O. leedsi, O. humerocristatus, O. manselli, and O. (?) greppini, with the genus representing taxon within Cetiosauridae alongside Cetiosaurus, Bothriospondylus, Pelorosaurus, Dinodocus, and possibly Rhoetosaurus and "Morosaurus" brevis. Later in the same year, Huene revised his classification, naming the new genus Cetiosauriscus for O. leedsi as described by Woodward, and O. (?) greppini. As the holotype material of Ornithopsis/Cetiosauriscus leedsii was not