page_title: Cetiosauriscus
section_title: Background
hierarchical_section_title: Cetiosauriscus / History of discovery / Background
caption_attribution_description: Cetiosaurus oxoniensis, Natural History Museum
context_page_description: Cetiosauriscus is a genus of sauropod dinosaur that lived between 166 and 164 million years ago during the Callovian in what is now England. A herbivore, Cetiosauriscus had—for sauropod standards—a moderately long tail, and longer forelimbs, making them as long as its hindlimbs. It has been estimated as about 15 m long and between 4 and 10 t in weight.
  The only known fossil that was later named Cetiosauriscus includes most of the rear half of a skeleton as well as a hindlimb. Found in Cambridgeshire in the 1890s, it was described by Arthur Smith Woodward in 1905 as a new specimen of the species Cetiosaurus leedsi. This was changed in 1927, when Friedrich von Huene found NHMUK R3078 and the C. leedsi type specimen to be too different from Cetiosaurus, warranting its own genus, which he named Cetiosauriscus, meaning "Cetiosaurus-like". Cetiosauriscus leedsi was referred to the sauropod family Diplodocidae because of similarities in the tail and foot, and had the dubious or intermediate species "Cetiosauriscus" greppini, "C." longus, and "C." glymptonensis assigned to it.
context_section_description: The fossil later known as Cetiosauriscus was originally ascribed to the genus Cetiosaurus—one of the first sauropods to be named, in 1842 by palaeontologist Richard Owen, and one with a complicated history due to many unfounded referrals of species and specimens, involving almost all English sauropod specimens. The type species of Cetiosaurus has changed throughout history because of incomplete remains and the taxon's significance, and many aspects of its anatomy and relationships are still uncertain. Cetiosaurus was originally named to include C. medius, C. brevis, C. brachyurus and C. longus, which span from the Middle Jurassic to the Early Cretaceous of various localities across England. As none of these species are truly diagnostic, and Cetiosaurus is a historically and taxonomically important taxon, the more complete Middle Jurassic species C. oxoniensis named by geologist John Phillips in 1871 became the type species. C. glymptonensis was also named in the same publication by Phillips, but is less complete and of a questionable validity.
  Another English taxon, Ornithopsis hulkei, was named in 1870 by palaeontologist Harry Govier Seeley for vertebrae from the Early Cretaceous Wessex Formation, younger than the existing species of Cetiosaurus. Seeley considered Ornithopsis to be closely related to Cetiosaurus, but different due to the internal bone structure. An additional species, Ornithopsis leedsii was named in 1887 by John Hulke for a pelvis, vertebrae and ribs collected by Alfred Nicholson Leeds, an English farmer and amateur fossil collector who throughout his life compiled numerous collections of fossils from the Oxford Clay. O. leedsii, from the Late Jurassic, showed similarities to older Cetiosaurus oxoniensis as well as younger O. hulkei. It was described in more detail by Seeley in 1889, where he considered O. hulkei, C. oxoniensis and O. leedsii to all be in the same genus, bearing the name Cetiosaurus. But naturalist Richard Lydekker discussed with Seeley, before the publication of Seeley's 1889 paper, that Cetiosaurus and Ornithopsis were not the same taxon. Lydekker suggested that Wealden fossils (including O. hulkei) belonged to Ornithopsis and the Jurassic remains (including O. leedsii and C. oxoniensis) to Cetiosaurus. Lydekker in 1895 changed his mind and referred the species O. leedsii to Pelorosaurus (known already from the species P. brevis, once named Cetiosaurus brevis)—as P. leedsi—and referred the genus to Atlantosauridae. Lydekker's classification of the species was not supported by later authors like palaeontologist Arthur Smith Woodward in 1905, who followed Seeley's classification scheme.
caption: Fossil limbs and vertebrae of Cetiosaurus oxoniensis
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