Cetiosaurus

*Cetiosaurus medius*

***Cetiosaurus*** (SEET-ee-oh-sawr-us) meaning 'whale lizard', from the Greek cetus/κητος meaning 'sea monster' (later, 'whale') and saurus/σαυρος meaning 'lizard', was a sauropod dinosaur from the Mid to Late Jurassic Period (181-169 million years ago) in what are now Europe and Africa. It is estimated to have been about 53 feet (16 m) long and to have weighed roughly 24.8 tonnes (27.3 short tons). It was so named because its discoverer, Sir Richard Owen supposed it was a marine creature, initially an extremely large crocodile.

## Discovery and species

### Initial finds

*Cetiosaurus* was, with the exception of the tooth genus *Cardiodon*, the first sauropod to be discovered and named as well as being the best known sauropod from England. Numerous species have been assigned to *Cetiosaurus* over the years belonging to several different groups of sauropod dinosaurs. The genus thus functioned as a typical "wastebasket taxon". Fossilized remains once assigned to *Cetiosaurus* have mainly been found in England but also in France, Switzerland and Morocco.

The first fossils, vertebrae and limb elements, were discovered near Chipping Norton in the early nineteenth century and were reported upon by collector John Kingdon in a letter read on 3 June 1825 to the Geological Society; they were seen as possibly belonging to a whale or crocodile. In 1841 biologist, comparative anatomist and palaeontologist Sir Richard Owen, named these as the genus *Cetiosaurus*, the year before he coined the term Dinosauria. Owen initially did not recognise *Cetiosaurus* for a dinosaur but considered it a gigantic sea-dwelling reptile. This was reflected by the name, derived from Greek κήτειος, kèteios, "sea-monster". In 1842 Owen named two species in the genus: *Cetiosaurus hypoolithicus* and *Cetiosaurus epioolithicus*. The specific names reflected whether the finds had been made below (hypo) or above (epi) the so-called oolithic layers. The first species was based on the material of Kingdon; the latter on vertebrae and metacarpals found at White Nab in Yorkshire. The publication did not contain a sufficient description and the species are often considered *nomina nuda*. The same year in a subsequent publication Owen named four additional *Cetiosaurus* species: *Cetiosaurus brevis*, "the short one"; *Cetiosaurus brachyurus*, "the short-tailed"; *Cetiosaurus medius*, "the medium-sized", and *Cetiosaurus longus*, "the long one". Owen had abandoned the two earlier names, as shown by the fact that their fossils were referred to several of the new species. These again were each mostly based on disparate material, from often geographically widely separated sites. As became apparent in 1849, some of these bones were not sauropod in nature at all but of Iguanodontidae. That year Alexander Melville, in a misguided attempt to clear matters up, named the authentic sauropod material of *C. brevis* as *Cetiosaurus conybeari* but thereby merely created a junior objective synonym of the former name

### *Cetiosaurus oxoniensis*

In March 1868, workers near Bletchingdon discovered a sauropod right femur. Between March 1869 and June 1870 Professor John Phillips, further investigating the site, in a layer dating from the Bathonian uncovered three skeletons and additional bone material. In 1871 based on these he named two species: *Cetiosaurus oxoniensis* (originally spelled *Ceteosaurus Oxoniensis*) and *Cetiosaurus glymptonensis*. "Oxoniensis" refers to Oxford, "glymptonensis" to Glympton. Already in 1870 Thomas Huxley had published a letter by Phillips in which the latter named a *Cetiosaurus giganteus* based on specimen OUMNH J13617, a left femur earlier found at Bletchingdon; as the letter did not contain a description, this is a *nomen nudum*.

### Later species

In 1874, John Whitaker Hulke named *Cetiosaurus humerocristatus*, "with a crested humerus", based on specimen BMNH 44635, a humerus found that year at Sandsfoot near Weymouth in Dorset. In 2010, this was made a separate genus *Duriatitan*. In 1905, Arthur Smith Woodward renamed *Ornithopsis leedsii* Hulke 1887 into *Cetiosaurus leedsi*. This today is often considered a *nomen dubium*. In 1970 Rodney Steel renamed *Cardiodon* Owen 1841, based on a now lost tooth, into *Cetiosaurus rugulosus*, "the wrinkled one". If the species were cogeneric to *Cetiosaurus*, the name of the genus would however be *Cardiodon* as this name has priority. In 2003, Upchurch & Martin rejected the identity.

In addition to the thirteen species based on British material, three were named by French researchers. In 1874, Henri-Émile Sauvage named *Cetiosaurus rigauxi* based on a vertebra found by Edouard Edmond Joseph Rigaux at Le Portel, west of Boulogne-sur-Mer, in layers dating from the Tithonian. In 1903 however, he was forced to conclude it represented a pliosaurid. In 1880, Sauvage named another species: *Cetiosaurus philippsi*. In 1955, Albert-Félix de Lapparent named *Cetiosaurus mogrebiensis* based on three skeletons found in Morocco from the El Mers Formation dating to the Bathonian. The specific name refers to the Maghreb. This is today sometimes seen as a valid taxon, but one not belonging to *Cetiosaurus*. In 2011, Eric Buffetaut e.a. referred a chevron found in the French Ardennes, specimen A775, to a *Cetiosaurus* sp.

A single *Cetiosaurus* species has been based on Swiss material. In 1932, Friedrich von Huene renamed *Ornithopsis greppini* Huene 1922 into *Cetiosaurus greppini*. This is today considered a *nomen dubium*.

### 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. The best known species is *C. oxoniensis* from the Middle Jurassic, and the genus *Cetiosaurus* had generally come to be identified with it. On the material of *C. brevis* on the other hand, the genus *Pelorosaurus* had meanwhile been based, representing a totally different sauropod from the Early Cretaceous. Therefore Upchurch & Martin suggested to request the ICZN to change the type species into *C. oxoniensis*. However, when in 2009 the request was filed, Upchurch & Martin had considerably changed their position. They now acknowledged that being a nomen dubium does not bar a species from being 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 only known from undiagnostic material. Its syntype series consists of eleven separate caudal vertebrae, (specimina OUMNH J13693–13703), some sacral ribs with a metatarsal (OUMNH J13704–13712), a metacarpal (OUMNH J13748), and a claw (OUMNH J13721), probably from different sites and individuals.

The ICZN accepted the proposal to change the type species in 2014 (Opinion 2331), officially making *C. oxoniensis* the type species in place of the original *C. medius*. Making *C. oxoniensis* the type species of *Cetiosaurus* secured the name *Cetiosaurus* for the animal with which it has been traditionally associated.

### Species list

The complex naming history can be summarised in a list of *Cetiosaurus* species:

* *Cetiosaurus hypoolithicus* Owen, 1841: nomen nudum
* *Cetiosaurus epioolithicus* Owen, 1841: nomen nudum
* *Cetiosaurus brachyurus* Owen, 1842: nomen dubium
* *Cetiosaurus longus* Owen, 1842: nomen dubium; = *Cetiosauriscus longus* (Owen, 1842) McIntosh, 1990
* *Cetiosaurus medius* Owen, 1842: nomen dubium, type species of *Cetiosaurus*
* *Cetiosaurus brevis* Owen, 1842: non *Cetiosaurus*, = *Cetiosaurus conybeari* Melville, 1849; = *Pelorosaurus conybearei* (Melville, 1849) Mantell, 1850; = *Pelorosaurus brevis* (Owen, 1842) Huene, 1927
* *Cetiosaurus giganteus* Owen vide Huxley, 1870: nomen nudum
* *Cetiosaurus oxoniensis* Phillips, 1871
* *Cetiosaurus glymptonensis* Phillips, 1871: non *Cetiosaurus*; = *Cetiosauriscus glymptonensis* (Phillips, 1871) McIntosh, 1990, non *Cetiosauriscus*
* *Cetiosaurus humerocristatus* Hulke, 1874: non Cetiosaurus; = *Ornithopsis humerocristatus* (Hulke, 1874) Lydekker, 1889; = *Pelorosaurus humerocristatus* (Hulke, 1874) Sauvage, 1897; = *Duriatitan humerocristatus* (Hulke, 1874) Barrett, Benson & Upchurch, 2010
* *Cetiosaurus rigauxi* Sauvage, 1874: non *Cetiosaurus*, pliosaurid
* *Cetiosaurus philippsi* Sauvage, 1880
* *Cetiosaurus mogrebiensis* de Lapparent, 1955: non *Cetiosaurus*

#### Misassigned to *Cetiosaurus* but originally described as nominal species of other genera

* *Cetiosaurus leedsi* (Hulke, 1887) Woodward, 1905: *nomen dubium*; = *Ornithopsis leedsii* Hulke, 1887
* *Cetiosaurus greppini* (Huene, 1922) Huene, 1932: *nomen dubium*, = *Ornithopsis greppini* Huene, 1922
* *Cetiosaurus rugulosus* (Owen, 1845) Steel, 1970: non *Cetiosaurus*, = *Cardiodon* Owen, 1841; = *Cardiodon rugulosus* Owen, 1845

## Description

*Cetiosaurus*, or specifically the neotype species *C. oxoniensis*, is known from relatively complete fossils. These include the three skeletons found by Phillips. One of these is a larger animal (catalogued as OUMNH J13605–13613, J13615–16, J13619–J13688 and J13899) that was chosen by Upchurch & Martin as the lectotype of the species; the second consists of limb bones of a smaller individual (OUMNH J13614) and the third skeleton represents the shoulder blade and hindlimb of a juvenile animal (OUMNNH J13617–8, J13780–1). The Rutland specimen, about 40% complete, increases considerably the number of known skeletal elements, especially in the neck. The skull is largely unknown, perhaps with the exception of the brain case represented by specimen OUMNH J13596. A single tooth crown, OUMNH J13597, has provisionally been referred to the species.

*Cetiosaurus* was, as any sauropod, a long-necked quadrupedal animal. In 2010, Gregory S. Paul estimated the body length at sixteen metres, the weight at eleven tonnes. Its neck was moderately long; no longer than its body. The tail was considerably longer, consisting of at least forty caudal vertebrae. Its dorsal vertebrae, the bones along the back, had the original heavy build with limited air chambers, unlike the extremely hollowed-out bones of later sauropods like *Brachiosaurus*. Its forearm was as long as the upper arm, unlike most other sauropods, resulting in a forelimb equalling the hindlimb in length. Its thigh bone was approximately six feet long.

In his original descriptions, Owen was unable to indicate any differences between *Cetiosaurus* and other sauropods for the simple reason these latter were not yet discovered. Now that such relatives have been found, the uniqueness of *Cetiosaurus oxoniensis* and its status as a valid taxon must be proven by indicating its new derived traits or autapomorphies. In their 2003 revision of the genus, Upchurch & Martin identified five autapomorphies of *C. oxoniensis*. The rear neck vertebrae and the front back vertebrae have spines on their tops that are low, symmetrical and in the shape of a pyramid. With the spines of all back vertebrae a ridge is absent between the spine and the diapophysis, the top rib joint; it has been lost or perhaps fused with the ridge running between the spine and the postzygapophysis, the rear joint process. The vertebrae of the middle tail have a tongue-shaped process at the top of the front face of the vertebral body; this is an extension of the floor of the neural canal. The chevrons of the front tail vertebrae have shafts of which the lower ends are flattened from the front to the rear in stead of transversely. The lower process of the ilium, to which the pubic bone was attached, features on the outer surface of its base a triangular depression.

## Classification and phylogeny

Owen initially was unsure about the precise relationships of *Cetiosaurus*. He understood it was a reptile and most researchers at the time accordingly assigned it to the Sauria. However, he at first did not recognise its dinosaurian nature; when in 1842 he named the Dinosauria, *Cetiosaurus* was not included. This was influenced by the preconception that such a large animal must have been sea-dwelling. Owen assumed crocodylian affinities. In the early 1850s, Gideon Mantell began to suspect that *Cetiosaurus* was a land animal as a result of his studies of *Pelorosaurus*. This idea however, was only slowly accepted by other scientists. In 1859 Owen still classified *Cetiosaurus* in the Crocodylia. In 1861, Owen concentrated all such forms in a group of their own: the Opisthocoelia. In 1869 Thomas Huxley stated explicitly that *Cetiosaurus* was a dinosaur.

In 1888 Lydekker assigned *Cetiosaurus* to its own family: the Cetiosauridae. For a long time this functioned as a large ill-defined family of typically "primitive" sauropods. Today however, many considerably more basal sauropods than *Cetiosaurus* are known. Modern exact cladistic research has not resulted in a single clear outcome about the position of *Cetiosaurus oxoniensis* in the sauropod tree. Sometimes a Cetiosauridae was recovered, a clade uniting *Cetiosaurus oxoniensis* with species as the Indian *Barapasaurus*, the South American *Patagosaurus* or the African *Chebsaurus*. Other studies indicate that the traditional Cetiosauridae were paraphyletic and recover *Cetiosaurus oxoniensis* in a basal position in the Eusauropoda, basal in the Neosauropoda or just outside of this clade.

## JPInstitute.com Description

The Cetiosaurus was the first sauropod ever discovered. It was located in England in 1841 by Richard Owen, who coined the word 'dinosaur.' Sauropods were giant, plant-eating dinosaurs. They laid eggs, had long necks and tails, small heads with tiny brains, and walked on four feet with five toes on each foot

Cetiosaurus was a rather primitive sauropod, with thick, nearly solid vertebra, and a neck and tail of only moderate length. It had the flattened, spoon-like teeth common to the earlier sauropods.

Cetiosaurids were a highly successful family of sauropods, lasting 35 million years. Other cetiosaurids included Barapasaurus, Bellusaurus, Datousaurus, Lapparentosaurus, Patagosaurus, Rhoetosaurus, and Shunosaurus.

The classification of sauropods is the subject of many debates, since many sauropods are known from only a few fossils, or even a single fossil.

## Links

http://web.archive.org/web/20031006231919/http://www.jpinstitute.com/dinopedia/dinocards/dc\_cetio.html

## References

1. ↑ F.A. Quenstedt, 1851, *Handbuch der Petrefaktenkunde*, H. Laupp'schen, Tübingen 792 pp
2. ↑ R. Owen, 1859, *Monograph on the fossil Reptilia of the Wealden and Purbeck formations. Supplement no. II. Crocodilia*, The Palaeontographical Society, London 1857: 20-44
3. ↑ R. Owen. 1861. *Palaeontology, or a Systematic Summary of Extinct Animals and their Geological Relations. Second Edition*. Adam and Charles Black, Edinburgh 463 pp
4. ↑ Template:Cite journal
5. ↑ R. Lydekker. 1888. *Catalogue of the Fossil Reptilia and Amphibia in the British Museum (Natural History). Part I, Containing the Orders Ornithosauria, Crocodilia, Dinosauria, Squamata, Rhynchocephalia, and Proterosauria*. British Museum (Natural History), London 309 pp
6. ↑ J.A. Wilson, 2002, "Sauropod dinosaur phylogeny: critique and cladistic analysis", *Zoological Journal of the Linnean Society* **136**: 217-276
7. ↑ D.T. Ksepka and M.A. Norell, 2010, "The Illusory Evidence for Asian Brachiosauridae: New Material of *Erketu ellisoni* and a Phylogenetic Reappraisal of Basal Titanosauriformes", *American Museum Novitates* **3700**: 1-27