Pelorosaurus

Pelorosaurus (/pəˌlɒroʊˈsɔːrəs/ pə-LORR-oh-SOR-əs; meaning "monstrous lizard") is a genus of titanosauriform sauropod dinosaur. Remains referred to Pelorosaurus date from the Early Cretaceous period, about 140-125 million years ago, and have been found in England and Portugal.

The name Pelorosaurus was one of the first to be given to any sauropod. Many species have been assigned to the genus historically, but most are currently considered to belong to other genera. Problematically, the first named species of Pelorosaurus, P. conybeari, is a junior synonym of Cetiosaurus brevis.

Pelorosaurus
Temporal range: Early Cretaceous, 132 Ma
Pelorosaurus
Holotype humerus
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Order: Saurischia
Suborder: Sauropodomorpha
Clade: Sauropoda
Family: Brachiosauridae
Genus: Pelorosaurus
Mantell, 1850
Species:
P. brevis
Binomial name
Pelorosaurus brevis
(Owen, 1842)
Synonyms

Cetiosaurus brevis Owen, 1842 Cetiosaurus conybeari Melville, 1849

History

Pelorosaurus conybeari
BMNH R28633, one of nine caudal vertebrae in 1853 referred by Owen to P. conybeari

Pelorosaurus was the first sauropod to be identified as a dinosaur, although it was not the first to be discovered. Richard Owen had discovered Cetiosaurus in 1841 but had incorrectly identified it as a gigantic sea-going crocodile-like reptile.[1] Mantell identified Pelorosaurus as a dinosaur, living on land.

The taxonomic history of Pelorosaurus and Cetiosaurus, as noted by reviewers including Michael P. Taylor and Darren Naish, is highly confusing. In 1842, Richard Owen named several species of Cetiosaurus. Among them was Cetiosaurus brevis, based on several specimens from the early Cretaceous Period. Some of these, four caudal vertebrae, BMNH R2544–2547, and three chevrons, BMNH R2548–2550, found around 1825 by John Kingdon near Cuckfield in the Tunbridge Wells Sand Formation of the Hastings Beds, belonged to sauropods. Others however, including BMNH R10390, found near Sandown Bay on the Isle of Wight, and BMNH R2133 and R2115, found near Hastings, actually belonged to some iguanodont. Noticing Owen's mistake in assigning iguanodont bones to Cetiosaurus, comparative anatomist Alexander Melville renamed the sauropod bones Cetiosaurus conybeari in 1849.[2][3]

In 1850, Gideon Mantell decided that C. conybeari was so different from Cetiosaurus that it needed a new genus, so he reclassified it under the new name Pelorosaurus Conybearei. Mantell had originally, in November 1849, intended to use the name "Colossosaurus", but upon discovering that kolossos was Greek for "statue" and not "giant", he changed his mind. The generic name is derived from the Greek pelor, "monster". He also emended the specific name (honouring William Conybeare) to conybearei, but under the present rules of the ICZN, the original conybeari, today written without a capital, has priority. Mantell not only used the sauropod material of C. brevis as the type of Pelorosaurus conybeari but also a large humerus found by miller Peter Fuller at the same site, BMNH 28626, which he assumed to have been of the same individual, being discovered only a few metres away from the vertebrae. Mantell acquired the bone for ₤8. The humerus, clearly shaped to vertically support the weight of the body and presumed to possess a medullary cavity, showed that Pelorosaurus was a land animal. This was a main motive in naming a separate genus; shortly afterwards, however, by studying the sacral vertebrae of Cetiosaurus Mantell established that it too lived on land.[4]

Cetiosaurus brevis
The caudal sauropod vertebrae that form the type specimen of C. brevis

Owen was highly piqued by Melville's and Mantell's attempts to "suppress" his Cetiosaurus brevis. By a publication in 1853 he tried to set matters straight, as he saw it, while avoiding having to openly admit his original mistake. First he suggested that Melville's main motivation for the name change was the presumed inaccuracy of the epithet brevis, "short", because the total length of the animal could not be deduced from such limited remains. Owen pointed out that anyone being acquainted with taxonomy would have understood that "short" referred to the vertebrae themselves, not to the animal as a whole. On a subsequent page, apparently separate from this issue, Owen in covert terms implied that his 1842 publication was not descriptive enough, thus merely having resulted in a nomen nudum, to which he now assigned the sauropod material, making Cetiosaurus brevis a valid name. This still left the problem of it having been named a new genus by Mantell. Owen resolved it by simply presenting the humerus as the sole holotype of Pelorosaurus conybeari.[5] Remarkably, in 1859 he repeated his mistake by again referring iguanodontid vertebrae, specimens BMNH R1010 and R28635, to C. brevis.[6] The last of these he had in 1853 proposed to belong to Pelorosaurus together with a number of other iguanodontid vertebrae because Mantell had once labelled them as such in his collection; Owen suggested it had been by a mere mistake that the name Pelorosaurus had been connected with the C. brevis material instead of with these finds.[5]

Pelorosaurus
Fanciful 1914 restoration of Pelorosaurus by Vincent Lynch

Owen's interpretation was commonly accepted until well into the twentieth century. By 1970 however, both John Ostrom and Rodney Steel understood that Owen's claim that C. brevis in 1842 was still a nomen nudum should be rejected as a transparent attempt to change the type specimen, inadmissible by present standards. By those same standards though, Melville's name change was also incorrect: as the name Cetiosaurus brevis was still "available" he should simply have made the sauropod bones the lectotype, removing the iguanodontid remains from the syntype series. The sauropod bones, not the iguanodont bones, would then have retained the name C. brevis. Therefore, Cetiosaurus conybeari is a junior objective synonym of C. brevis, that is, C. brevis is not only an older name, but one based on exactly the same fossils as the younger, invalid name.[3]

After 1850, more specimens continued to be assigned to both Pelorosaurus and Cetiosaurus, and both were studied and reported on extensively in the scientific literature.[3] Slowly a tendency developed to subsume fragmentary sauropod material from the Jurassic of England under the designation Cetiosaurus, while assigning incomplete European Cretaceous sauropod finds to Pelorosaurus. Pelorosaurus thus came to be a typical wastebasket taxon for any European sauropod of this period. However, in recent years much work has been done to rectify the confusion.

Classification

The validity of Pelorosaurus is problematic. P. conybeari was based on a separately discovered humerus and vertebrae. However, these specimens might not belong to the same animal. P. conybeari is also a junior synonym of the older name Cetiosaurus brevis. In 2007, Michael P. Taylor and Darren Naish stated their intention to petition the International Commission on Zoological Nomenclature (ICZN) in order to designate the more widely used name P. conybeari the type species of Pelorosaurus and officially abandon the name c. brevis.[7] However, the issue of the Pelorosaurus type species did not end up as part of their petition when it was officially filed and accepted.[8]

Many species have later been assigned to Pelorosaurus, most of which today are considered different dinosaurs. One notable species, P. becklesii, was known from a humerus, radius and ulna, as well as skin impressions. This specimen has since been made the new genus Haestasaurus.

Valid species

Cetiosaurus brevis dorsal vertebra
Dorsal vertebra assigned to Cetiosaurus brevis
  • Cetiosaurus brevis Owen 1842
    • Synonyms:
    • Cetiosaurus conybeari Melville 1849
    • Pelorosaurus conybearei (Melville 1849) Mantell 1850
    • Pelorosaurus brevis (Owen 1842) Huene 1927
    • Ornithopsis conybearei (Melville 1849) Huene 1929

Misassigned species

Relationships

Pelorosaurus2
Recreation
Pelorosaurus holotype
Holotype humerus lithograph

Mantell was the first to suggest a relationship between Pelorosaurus and dinosaurs. In 1852 Friedrich August Quenstedt formally listed it in the Dinosauria.[9] Predictably, Owen at first rejected this classification, still in 1859 considering it a member of the Crocodilia.

In 1882 Henri-Émile Sauvage first stated it belonged to the Sauropoda. That group being still very incompletely known however, it proved difficult to determine its more precise affinities, with the Atlantosauridae, Cardiodontidae, Cetiosauridae and Morosauridae being suggested until in 1927 von Huene understood the possible link with Brachiosaurus, placing Pelorosaurus in the Brachiosauridae, a placement followed by subsequent authors until the early 21st century. The humerus, 137 centimeters long and very elongated, strongly suggests a typical brachiosaurid trait was present: the possession of relatively long front limbs. The uncertainties about whether the qualities of the vertebrae or the humerus should be analysed, both specimens not necessarily belonging to the same taxon, prevents any firm conclusion to be reached, however. In recent years, the material was commonly placed in a more general Titanosauriformes.

References

  1. ^ Owen, R (1842). "Report on British fossil reptiles, Part II". Reports of the British Association for the Advancement of Science. 11: 60–204.
  2. ^ Melville, A.G. (1849). "Notes on the vertebral column of Iguanodon". Philosophical Transactions of the Royal Society of London. 139: 285–300. doi:10.1098/rstl.1849.0015.
  3. ^ a b c Taylor, M.P.; Naish, D. (2007). "An unusual new neosauropod dinosaur from the Lower Cretaceous Hastings Beds Group of East Sussex, England". Palaeontology. 50 (6): 1547–1564. doi:10.1111/j.1475-4983.2007.00728.x.
  4. ^ Mantell, G.A. (1850). "On the Pelorosaurus: an undescribed gigantic terrestrial reptile, whose remains are associated with those of the Iguanodon and other saurians in the strata of Tilgate Forest, in Sussex". Philosophical Transactions of the Royal Society of London. 140: 379–390. doi:10.1098/rstl.1850.0017.
  5. ^ a b Owen, R., 1853, Monograph on the fossil Reptilia of the Wealden and Purbeck formations, Palaeontological Society, London
  6. ^ Owen, R., 1859, Monograph on the fossil Reptilia of the Wealden and Purbeck formations. Supplement no. II. Crocodilia (Streptospondylus, etc.). [Wealden.] The Palaeontographical Society, London 1857: 20-44
  7. ^ Taylor, Michael P.; Naish, Darren (2007). "An unusual new neosauropod dinosaur from the Lower Cretaceous Hastings Beds Group of East Sussex, England" (PDF). Palaeontology. 50 (6): 1547–1564. doi:10.1111/j.1475-4983.2007.00728.x.
  8. ^ International Commission on Zoological Nomenclature. 2014. "OPINION 2331 (Case 3472): Cetiosaurus Owen, 1841 (Dinosauria, Sauropoda): usage conserved by designation of Cetiosaurus oxoniensis Phillips, 1871 as the type species". Bulletin of Zoological Nomenclature 71(1): 48-50
  9. ^ Quenstedt, F.A., 1852, Handbuch der Petrefaktenkunde, 1st edition. H. Laupp'schen, Tübingen pp. 1-792

Sources

  • Cadbury, D. (2001). The Dinosaur Hunters. Fourth Estate.
  • Lydekker, R. (1889). "Note on some points in the nomenclature of fossil reptiles and amphibians, with preliminary notices of two new species". Geological Magazine. 6 (decade 3): 325–326. doi:10.1017/s0016756800176472.
  • von Huene, F. (1927). "Sichtung der Grundlagen der jetzigen Kenntnis der Sauropoden [Sorting through the basis of the current knowledge of sauropods]". Eclogae Geologica Helveticae. 20: 444–470.
  • Steel, R. (1987) [1970]. "Saurischia". Handbuch der Paläoherpetologie/Encyclopedia of Paleoherpetology. Stuttgart: Gustav Fischer Verlag.
  • von Huene, F. (1909). "Skizze zu einer Systematik und Stammesgeschichte der Dinosaurier [Sketch of the systematics and origins of the dinosaurs]". Centralblatt für Mineralogie, Geologie und Paläontologie. =1909: 12–22.
  • Lydekker, R. (1893). "On two dinosaurian teeth from Aylesbury". Quarterly Journal of the Geological Society of London. 49 (1–4): 566–568. doi:10.1144/gsl.jgs.1893.049.01-04.64.
  • Upchurch, P.; Mannion, P. D.; Barrett, P. M. (2011). "Sauropod dinosaurs". In Batten, D. J. (ed.). English Wealden Fossils. London: The Palaeontological Association. pp. 476–525.
Berriasian

In the geological timescale, the Berriasian is an age or stage of the Early Cretaceous. It is the oldest, or lowest, subdivision in the entire Cretaceous. It spanned the time between 145.0 ± 4.0 Ma and 139.8 ± 3.0 Ma (million years ago). The Berriasian succeeds the Tithonian (part of the Jurassic) and precedes the Valanginian.

Bothriospondylus

Bothriospondylus ("excavated vertebra") is a dubious genus of sauropod dinosaur. It lived during the Late Jurassic.

Bugle Quarry

Bugle Quarry is a 0.08 hectare geological Site of Special Scientific Interest in Hartwell in Buckinghamshire. The local planning authority is Aylesbury Vale District Council. It has two entries in the Geological Conservation Review of the Joint Nature Conservation Committee.The site has been studied by geologists for over 150 years. In 1958 it was filled by the spoil from road improvements, but in the following year a section was re-exposed by geologists from Queen Mary College, London. It was again re-opened in 1984, but it is in an unsafe state and is protected by a fence.The site spans the Tithonian stage (c. 152-145 million years ago) in the late Jurassic, and the Berriasian (c. 145-139 million years ago) in the early Cretaceous. It was formerly the type section for the Portland (Tithonian) and Purbeck (Berriasian) Groups in the Aylesbury area; it has yielded an important sequence of ostracod fauna which spans the junction between the two stages, and the environmental change from land to sea. A number of dinosaur teeth have been found, including Pelorosaurus teeth which are the only sauropod teeth of Tithonian age in Europe. Teeth found of the carnosaur Megalosaurus are the only ones found of the same period in Britain.The site is in the grounds of Hartwell Riding Stables with no public access.

Cetiosaurus

Cetiosaurus () meaning 'whale lizard', from the Greek keteios/κήτειος meaning 'sea monster' (later, 'whale') and sauros/σαυρος meaning 'lizard', is a herbivorous sauropod dinosaur from the Middle Jurassic Period, living about 167 million years ago in what is now Europe and Africa.

Cetiosaurus was in 1842 the first sauropod from which bones were described and is the most complete sauropod found in England. It was so named because its describer, Sir Richard Owen, supposed it was a marine creature, initially an extremely large crocodile, and did not recognise it for a land-dwelling dinosaur. Because of the early description many species would be named in the genus, eventually eighteen of them. Most of these have now been placed in other genera or are understood to be dubious names, based on poor fossil material. The last is true also of the original type species, Cetiosaurus medius, and so C. oxoniensis was officially made the new type species in 2014. C. oxoniensis is based on three more or less complete specimens, discovered from 1868 onwards. Together they contain most of the bones, with the exception of the skull.

Cetiosaurus oxoniensis was a "primitive", quadrupedal, long-necked, small-headed herbivore. It had a shorter tail and neck than most sauropods. The forelimbs on the other hand, were relatively long. C. oxoniensis is estimated to have been about 16 metres (52 ft) long and to have weighed roughly 11 tonnes (12 short tons).

Dinodocus

Dinodocus (meaning "terrible beam") is a genus of sauropod dinosaur, named by Richard Owen in 1884. The name is now usually considered a nomen dubium. The only species, D. mackesoni, a name given to some fossil limb bones from the Lower Greensand (Lower Cretaceous) of Kent, England, was formerly placed in the genus Pelorosaurus (Mantell, 1850), but review by Upchurch et al. (2004) concludes that Dinodocus is a nomen dubium.

Duriatitan

Duriatitan is a genus of titanosauriform sauropod dinosaur that lived in the Late Jurassic in what is now England. The holotype specimen of Duriatitan, BMNH 44635, is a partial left upper arm bone which was found by R.I. Smith near Sandsfoot in the lower Kimmeridge Clay from Dorset. The type species, D. humerocristatus, was described in 1874 by John Hulke as a species of Cetiosaurus. The specific name refers to the deltopectoral crest, crista, on the upper arm bone, humerus. The specimen was assigned to its own genus by Paul M. Barrett, Roger B.J. Benson and Paul Upchurch in 2010. The generic name is derived from the Latin name for Dorset, Duria, and Greek Titan.

Eucamerotus

Eucamerotus (meaning "well-chambered" in reference to the hollows of the vertebrae) was a genus of sauropod dinosaur from the Barremian-age Lower Cretaceous Wessex Formation (Wealden) of the Isle of Wight, England.

Ferganasaurus

Ferganasaurus was a genus of dinosaur first formally described in 2003 by Alifanov and Averianov. The type species is Ferganasaurus verzilini. It was a sauropod similar to Rhoetosaurus. The fossils were discovered in 1966 in Kyrgyzstan from the Balabansai Formation and date to the Callovian stage of the Middle Jurassic.

Flagellicaudata

Flagellicaudata is a clade of Dinosauria. It belongs to Sauropoda and includes two families, the Dicraeosauridae and the Diplodocidae.

Gigantosaurus

Gigantosaurus (from the Greek "Γίγας" and "σαυρος", meaning "giant lizard") is a sauropod dinosaur genus from the Late Jurassic Kimmeridge Clay Formation of England. The type species, Gigantosaurus megalonyx, was named and described by Harry Govier Seeley in 1869. Its syntype series consists of several separately discovered sauropod bones found in Cambridgeshire, including two caudal (tail) vertebrae (CAMSM J.29477 and CAMSM J.29478), the distal end of a tibia (CAMSM J.29483), a cast of the right radius (CAMSM J.29482), a cast of phalanx (CAMSM J.29479) and an osteoderm (CAMSM J.29481). It was synonymised to Ornithopsis humerocristatus by Richard Lydekker in 1888 and to Pelorosaurus by Friedrich von Huene in 1909. Today it is considered a nomen dubium.

Because of these references Eberhard Fraas incorrectly assumed in 1908 the name was available for other species and he used it, despite it being preoccupied, for African material totally unrelated to the British finds. As a result, the name Gigantosaurus factored into the convoluted taxonomic history of the African dinosaurs Barosaurus, Tornieria, and Janenschia. A discussion of this can be found in the main Tornieria article.

Haestasaurus

Haestasaurus is a genus of herbivorous sauropod dinosaur, belonging to the Macronaria, that during the Early Cretaceous lived in the area of present-day England. The only species is Haestasaurus becklesii.

Hastings Beds

The Hastings Beds is a geological unit that includes interbedded clays, silts, siltstones, sands and sandstones in the High Weald of southeast England. These strata make up the component geological formations of the Ashdown Formation, the Wadhurst Clay Formation and the Tunbridge Wells Sand Formation. The term 'Hastings Beds' has been superseded and the component formations are included in the Wealden Group.The sediments of the Weald, including the Hastings Beds, were deposited during the Early Cretaceous Period, which lasted for approximately 40 million years from 140 to 100 million years ago. The Hastings Beds are of Early Berriasian to Late Valanginian age. The Group takes its name from the fishing town of Hastings in East Sussex.

Dinosaur remains are among the fossils that have been recovered from the included formations.

Holotype

A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of several such, but explicitly designated as the holotype. Under the International Code of Zoological Nomenclature (ICZN), a holotype is one of several kinds of name-bearing types. In the International Code of Nomenclature for algae, fungi, and plants (ICN) and ICZN the definitions of types are similar in intent but not identical in terminology or underlying concept.

For example, the holotype for the butterfly Lycaeides idas longinus is a preserved specimen of that species, held by the Museum of Comparative Zoology at Harvard University. An isotype is a duplicate of the holotype and is often made for plants, where holotype and isotypes are often pieces from the same individual plant or samples from the same gathering.

A holotype is not necessarily "typical" of that taxon, although ideally it should be. Sometimes just a fragment of an organism is the holotype, particularly in the case of a fossil. For example, the holotype of Pelorosaurus humerocristatus (Duriatitan), a large herbivorous dinosaur from the early Jurassic period, is a fossil leg bone stored at the Natural History Museum in London. Even if a better specimen is subsequently found, the holotype is not superseded.

Huangshanlong

Huangshanlong is a genus of mamenchisaurid dinosaurs native to the Anhui province of China. It contains a single species, Huangshanlong anhuiensis. H. anhuiensis represents, along with Anhuilong and Wannanosaurus, one of three dinosaurs fround in Anhui province.

Ischyrosaurus

"Ischyrosaurus" (meaning "strong lizard", for its large humerus; name in quotation marks because it is preoccupied) was a genus of sauropod dinosaur from the Kimmeridgian-age Upper Jurassic Kimmeridge Clay of Dorset, England. It was once synonymized with the Early Cretaceous-age Pelorosaurus.

Morinosaurus

Morinosaurus (meaning "Morini lizard", for an ancient people of northern France) was a genus of sauropod dinosaur from an unnamed formation of Kimmeridgian-age Upper Jurassic rocks from Boulogne-sur-Mer, Départment du Pas-de-Calais, France. It is an obscure tooth genus sometimes referred to the Lower Cretaceous English wastebasket taxon Pelorosaurus.

Neosodon

Neosodon (meaning "new tooth") was a genus of sauropod dinosaur from the Late Tithonian-age Upper Jurassic Sables et Gres a Trigonia gibbosa of Départment du Pas-de-Calais, France. It has never been formally given a species name, but is often seen as N. praecursor, which actually comes from a different animal. Often in the past, it had been assigned to the wastebasket taxon Pelorosaurus, but restudy has suggested that it could be related to Turiasaurus, a roughly-contemporaneous giant Spanish sauropod.

Oplosaurus

Oplosaurus (meaning "armed or weapon lizard" or "armoured lizard"; see below for discussion) was a genus of sauropod dinosaur from the Barremian-age Lower Cretaceous Wessex Formation of the Isle of Wight, England. It is known from a single tooth usually referred to the contemporaneous "wastebasket taxon" Pelorosaurus, although there is no solid evidence for this.

Sibirotitan

Sibirotitan ("Siberian titan") is a genus of somphospondyl sauropod from the Ilek Formation of Russia. The type and only species is S. astrosacralis.

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