Friedrich von Huene renamed Ornithopsis greppini Huene 1922 into Cetiosaurus greppini. This is today considered a nomen dubium. In 2020, it was proposed to assigned C. greppini to the new genus Amanzia. The question of the type species In principle for every genus a type species must be indicated to serve as its type in an ostensive definition. Traditionally, C. medius had been considered the type species of Cetiosaurus. In 1888 Richard Lydekker had formally assigned C. oxoniensis as the type species but by the modern rules of the ICZN one of the species named by the original author, in this case Owen, must be selected. In 2003, Paul Upchurch and John Martin determined that C. "hypoolithicus" and C. "epioolithicus" could not be used because they were nomina nuda. Of the four species named in Owen's second 1842 article, C. brevis, C. brachyurus, C. longus and C. medius, only C. brevis would not be a nomen dubium. This they interpreted as implying that C. brevis was the type species. This conclusion, if correct, would cause considerable taxonomic instability, because the genus Pelorosaurus had since been based on its fossils, and recognized as a totally different kind of sauropod. Therefore, Upchurch & Martin suggested to request the ICZN to change the type species into C. oxoniensis, the best known species from the Middle Jurassic, which the genus Cetiosaurus had generally come to be identified with. However, in 2009, when their request was officially filed, Upchurch and Martin had changed their position. They acknowledged that being designated a nomen dubium does not prevent a species from having been made the type of a genus. Furthermore, they had identified a passage in the 1842 article in which Owen himself had already assigned C. medius as the type species: "it is principally on these bones [i.e. those of C. medius], with others subsequently discovered and in the collection of Mr. Kingdon, that the characters of the Cetiosaurus were first determined". Nevertheless, they still advocated a change in type because C. medius is known only from undiagnostic material. Its syntype series consists of eleven separate tail vertebrae, (specimina OUMNH J13693–13703), some sacral ribs with a foot bone (metatarsal, OUMNH J13704–13712), a hand bone (metacarpal, OUMNH J13748), and a claw (OUMNH J13721), probably from different fossil sites and different individuals. The ICZN accepted the proposal to change the type species in 2014 (Opinion 2331), officially making