Pelorosaurus
Encyclopedia
Pelorosaurus was a huge plant-eating dinosaur
. Pelorosaurus was one of the first sauropod dinosaurs ever discovered. Pelorosaurus lived during the Early Cretaceous
period, about 138-112 million years ago. Fossils referred to Pelorosaurus have been found in England
and Portugal
. It was about sixteen metres (50 feet) long.
It is problematic whether Pelorosaurus is a valid genus and if so, what its valid species are. Of the fossils the first species of Pelorosaurus, P. conybeari, was based on, a separately discovered humerus and vertebrae, the latter are the type specimen of the species and the former is seen as the holotype
of the genus. Both specimens might not be of the same animal; furthermore, P. conybeari is a junior synonym of Cetiosaurus brevis. Many species have later been assigned to Pelorosaurus, most of which today are considered different dinosaurs. One later species still not having received a separate generic name, P. becklesi, is known from a sacrum, pelvis and limb fragments, as well as from skin impressions; it was covered in hexagonal scales.
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. Mantell identified Pelorosaurus as a dinosaur, living on land.
The taxonomic history of Pelorosaurus and Cetiosaurus, as noted by reviewers including Taylor and Naish
, is confusing to the extreme. In 1842 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 layers of the Hastings Beds Group, belonged to sauropods. Others however, among them perhaps the present specimen BMNH R10390 found near Sandow Bay on the Isle of Wight
and BMNH R2133 and R2115 found near Hastings, actually belonged to some member of the Iguanodontidae. Noticing Owen's mistake in assigning iguanodont bones to Cetiosaurus, in 1849 comparative anatomist Alexander Melville re-named the sauropod bones Cetiosaurus conybeari.
Gideon Mantell
in 1850 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 present rules 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.
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. Remarkably, in 1859 he repeated his mistake by again referring iguanodontid vertebrae, specimens BMNH R1010 and R28635, to C. brevis.
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. C. conybeari is thus a nomen vanum, a failed changed name. As a consequence, Pelorosaurus conybeari also is a junior objective synonym of C. brevis.
This has become further confused because some researchers in the early 21st century regarded C. brevis as the type species
of Cetiosaurus. If this were the case, then Cetiosaurus was not a sauropod from the Middle Jurassic
as long thought, but was technically the synonym of a much different sauropod from the Early Cretaceous
. Further study on the taxonomy of Cetiosaurus has, however, shown that C. brevis is not the type species of Cetiosaurus but C. medius.
The taxonomic status of Pelorosaurus is as a result very problematic. Technically, Cetiosaurus brevis is its type species. This might result in the combination Pelorosaurus brevis, a solution already chosen by Friedrich von Huene
in 1927. Alternatively, the humerus might be assigned as the neotype of Pelorosaurus conybeari, as suggested in 2003 by Paul Upchurch and John Martin
. Many sources still indicate BMNH 28626 as the genoholotype of the genus Pelorosaurus as such. The position of Pelorosaurus is further undermined by the fact that several researchers hold that the genus is a nomen dubium
.
assigned to Morosaurus as a Morosaurus becklesii after which Richard Lydekker
the same year coined the combination Morosaurus brevis as he considered it cospecific with Cetiosaurus brevis but different from Pelorosaurus conybeari — which is impossible under the present interpretation.
To an undetermined Pelorosaurus sp. five specimens have been assigned, among which teeth, bone fragments and a shoulder girdle from France
but also two finds from England, the most remarkable being four gastrolith
s, BMNH R2004/BMNH R2565, discovered in Buckinghamshire
in 1894.
.
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 Brachiosaurinae. The genus was subsequently commonly considered a member of Brachiosauridae
. 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.
Dinosaur
Dinosaurs are a diverse group of animals of the clade and superorder Dinosauria. They were the dominant terrestrial vertebrates for over 160 million years, from the late Triassic period until the end of the Cretaceous , when the Cretaceous–Paleogene extinction event led to the extinction of...
. Pelorosaurus was one of the first sauropod dinosaurs ever discovered. Pelorosaurus lived during the Early Cretaceous
Cretaceous
The Cretaceous , derived from the Latin "creta" , usually abbreviated K for its German translation Kreide , is a geologic period and system from circa to million years ago. In the geologic timescale, the Cretaceous follows the Jurassic period and is followed by the Paleogene period of the...
period, about 138-112 million years ago. Fossils referred to Pelorosaurus have been found in England
England
England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...
and Portugal
Portugal
Portugal , officially the Portuguese Republic is a country situated in southwestern Europe on the Iberian Peninsula. Portugal is the westernmost country of Europe, and is bordered by the Atlantic Ocean to the West and South and by Spain to the North and East. The Atlantic archipelagos of the...
. It was about sixteen metres (50 feet) long.
It is problematic whether Pelorosaurus is a valid genus and if so, what its valid species are. Of the fossils the first species of Pelorosaurus, P. conybeari, was based on, a separately discovered humerus and vertebrae, the latter are the type specimen of the species and the former is seen as the holotype
Holotype
A holotype is a single physical example of an organism, known to have been used when the species was formally described. It is either the single such physical example or one of several such, but explicitly designated as the holotype...
of the genus. Both specimens might not be of the same animal; furthermore, P. conybeari is a junior synonym of Cetiosaurus brevis. Many species have later been assigned to Pelorosaurus, most of which today are considered different dinosaurs. One later species still not having received a separate generic name, P. becklesi, is known from a sacrum, pelvis and limb fragments, as well as from skin impressions; it was covered in hexagonal scales.
History
Richard Owen
Sir Richard Owen, FRS KCB was an English biologist, comparative anatomist and palaeontologist.Owen is probably best remembered today for coining the word Dinosauria and for his outspoken opposition to Charles Darwin's theory of evolution by natural selection...
had discovered Cetiosaurus
Cetiosaurus
Cetiosaurus meaning 'whale lizard', from the Greek cetus/κητος meaning 'sea monster' and saurus/σαυρος meaning 'lizard', was a sauropod dinosaur from the Mid to Late Jurassic Period in what are now Europe and Africa. It is estimated to have been about long and to have weighed roughly...
in 1841 but had incorrectly identified it as a gigantic sea-going crocodile-like reptile. Mantell identified Pelorosaurus as a dinosaur, living on land.
The taxonomic history of Pelorosaurus and Cetiosaurus, as noted by reviewers including Taylor and Naish
Darren Naish
Darren Naish is a vertebrate palaeontologist and science writer. He obtained a geology degree at the University of Southampton and later studied vertebrate palaeontology under British palaeontologist David Martill at the University of Portsmouth, where he obtained both an M. Phil...
, is confusing to the extreme. In 1842 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
Cuckfield
Cuckfield is a large village and civil parish in the Mid Sussex District of West Sussex, England, on the southern slopes of the Weald. It lies south of London, north of Brighton, and east northeast of the county town of Chichester. Nearby towns include Haywards Heath to the southeast and Burgess...
in layers of the Hastings Beds Group, belonged to sauropods. Others however, among them perhaps the present specimen BMNH R10390 found near Sandow Bay on the Isle of Wight
Isle of Wight
The Isle of Wight is a county and the largest island of England, located in the English Channel, on average about 2–4 miles off the south coast of the county of Hampshire, separated from the mainland by a strait called the Solent...
and BMNH R2133 and R2115 found near Hastings, actually belonged to some member of the Iguanodontidae. Noticing Owen's mistake in assigning iguanodont bones to Cetiosaurus, in 1849 comparative anatomist Alexander Melville re-named the sauropod bones Cetiosaurus conybeari.
Gideon Mantell
Gideon Mantell
Gideon Algernon Mantell MRCS FRS was an English obstetrician, geologist and palaeontologist...
in 1850 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
Ancient Greek
Ancient Greek is the stage of the Greek language in the periods spanning the times c. 9th–6th centuries BC, , c. 5th–4th centuries BC , and the c. 3rd century BC – 6th century AD of ancient Greece and the ancient world; being predated in the 2nd millennium BC by Mycenaean 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 present rules 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
Humerus
The humerus is a long bone in the arm or forelimb that runs from the shoulder to the elbow....
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
Medullary cavity
The medullary cavity is the central cavity of bone shafts where red bone marrow and/or yellow bone marrow is stored; hence, the medullary cavity is also known as the marrow 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.
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
Nomen nudum
The phrase nomen nudum is a Latin term, meaning "naked name", used in taxonomy...
, 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
Holotype
A holotype is a single physical example of an organism, known to have been used when the species was formally described. It is either the single such physical example or one of several such, but explicitly designated as the holotype...
of Pelorosaurus conybeari. Remarkably, in 1859 he repeated his mistake by again referring iguanodontid vertebrae, specimens BMNH R1010 and R28635, to C. brevis.
Owen's interpretation was commonly accepted until well into the twentieth century. By 1970 however, both John Ostrom
John Ostrom
John H. Ostrom was an American paleontologist who revolutionized modern understanding of dinosaurs in the 1960s, when he demonstrated that dinosaurs are more like big non-flying birds than they are like lizards , an idea first proposed by Thomas Henry Huxley in the 1860s, but which had garnered...
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
Lectotype
In botanical nomenclature and zoological nomenclature, a lectotype is a kind of name-bearing type. When a species was originally described on the basis of a name-bearing type consisting of multiple specimens, one of those may be designated as the lectotype...
, removing the iguanodontid remains from the syntype
Syntype
In biological nomenclature, a syntype is a term used to indicate a specimen with a special status.In zoological nomenclature, a syntype is defined as "Each specimen of a type series from which neither a holotype nor a lectotype has been designated [Arts. 72.1.2, 73.2, 74]. The syntypes...
series. The sauropod bones, not the iguanodont bones, would then have retained the name C. brevis. Therefore, Cetiosaurus conybeari is a junior objective synonym
Synonym (taxonomy)
In scientific nomenclature, a synonym is a scientific name that is or was used for a taxon of organisms that also goes by a different scientific name. For example, Linnaeus was the first to give a scientific name to the Norway spruce, which he called Pinus abies...
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. C. conybeari is thus a nomen vanum, a failed changed name. As a consequence, Pelorosaurus conybeari also is a junior objective synonym of C. brevis.
This has become further confused because some researchers in the early 21st century regarded C. brevis as the type species
Type species
In biological nomenclature, a type species is both a concept and a practical system which is used in the classification and nomenclature of animals and plants. The value of a "type species" lies in the fact that it makes clear what is meant by a particular genus name. A type species is the species...
of Cetiosaurus. If this were the case, then Cetiosaurus was not a sauropod from the Middle Jurassic
Middle Jurassic
The Middle Jurassic is the second epoch of the Jurassic Period. It lasted from 176-161 million years ago. In European lithostratigraphy, rocks of this Middle Jurassic age are called the Dogger....
as long thought, but was technically the synonym of a much different sauropod from the Early Cretaceous
Early Cretaceous
The Early Cretaceous or the Lower Cretaceous , is the earlier or lower of the two major divisions of the Cretaceous...
. Further study on the taxonomy of Cetiosaurus has, however, shown that C. brevis is not the type species of Cetiosaurus but C. medius.
The taxonomic status of Pelorosaurus is as a result very problematic. Technically, Cetiosaurus brevis is its type species. This might result in the combination Pelorosaurus brevis, a solution already chosen by Friedrich von Huene
Friedrich von Huene
Friedrich von Huene was a German paleontologist who named more dinosaurs in the early 20th century than anyone else in Europe.-Biography:...
in 1927. Alternatively, the humerus might be assigned as the neotype of Pelorosaurus conybeari, as suggested in 2003 by Paul Upchurch and John Martin
John Martin
-In the arts:*John H. Martin, American actor in TV soap operas One Life to Live and Sunset Beach*John Martin , English-born Canadian broadcaster*John Martin , dance critic at the New York Times...
. Many sources still indicate BMNH 28626 as the genoholotype of the genus Pelorosaurus as such. The position of Pelorosaurus is further undermined by the fact that several researchers hold that the genus is a nomen dubium
Nomen dubium
In zoological nomenclature, a nomen dubium is a scientific name that is of unknown or doubtful application...
.
Further species
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. 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.New species of Pelorosaurus
One of the later species of Pelorosaurus was completely new. In 1852 Mantell named Pelorosaurus becklesii based on a humerus (BMNH R-1868), ulna and radius found near Hastings. The specific name honours the fossil collector Samuel Husband Beckles. The find included skin impressions of large hexagonal scales. Today it is understood these remains have no provable connection with BMNH 28626 or Cetiosaurus brevis. "Pelorosaurus" becklesi — today spelled with a single "i" — is likely a different titanosauriform, for which a separate genus has yet to be named. Confusingly this species was in 1889 by Othniel Charles MarshOthniel Charles Marsh
Othniel Charles Marsh was an American paleontologist. Marsh was one of the preeminent scientists in the field; the discovery or description of dozens of news species and theories on the origins of birds are among his legacies.Born into a modest family, Marsh was able to afford higher education...
assigned to Morosaurus as a Morosaurus becklesii after which Richard Lydekker
Richard Lydekker
Richard Lydekker was an English naturalist, geologist and writer of numerous books on natural history.-Biography:...
the same year coined the combination Morosaurus brevis as he considered it cospecific with Cetiosaurus brevis but different from Pelorosaurus conybeari — which is impossible under the present interpretation.
To an undetermined Pelorosaurus sp. five specimens have been assigned, among which teeth, bone fragments and a shoulder girdle from France
France
The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...
but also two finds from England, the most remarkable being four gastrolith
Gastrolith
A gastrolith, also called a stomach stone or gizzard stones, is a rock held inside a gastrointestinal tract. Gastroliths are retained in the muscular gizzard and used to grind food in animals lacking suitable grinding teeth. The grain size depends upon the size of the animal and the gastrolith's...
s, BMNH R2004/BMNH R2565, discovered in Buckinghamshire
Buckinghamshire
Buckinghamshire is a ceremonial and non-metropolitan home county in South East England. The county town is Aylesbury, the largest town in the ceremonial county is Milton Keynes and largest town in the non-metropolitan county is High Wycombe....
in 1894.
Existing species assigned to Pelorosaurus
Several species named in other genera have been reassigned to Pelorosaurus. This resulted, in chronological order, in a Pelorosaurus hulkei, Pelorosaurus armatus, Pelorosaurus leedsi, Pelorosaurus humerocristatus, Pelorosaurus praecursor and a Pelorosaurus mackesoni. None of these identifications is today seen as correct.Species list
- Cetiosaurus brevisCetiosaurusCetiosaurus meaning 'whale lizard', from the Greek cetus/κητος meaning 'sea monster' and saurus/σαυρος meaning 'lizard', was a sauropod dinosaur from the Mid to Late Jurassic Period in what are now Europe and Africa. It is estimated to have been about long and to have weighed roughly...
Owen 1842 (type) = Cetiosaurus conybeari Melville 1849, = Pelorosaurus conybearei (Melville 1849) Mantell 1850, = P. brevis (Owen 1842) von Huene 1927, = Ornithopsis conybeareiOrnithopsisOrnithopsis was a medium-sized Early Cretaceous sauropod dinosaur, from England. It has been considered a synonym of the wastebasket taxon Pelorosaurus, but recent research suggests that this is not as clear-cut as supposed...
(Melville 1849) von Huene 1929 - P. becklesii Mantell 1852
- P. manseli Hulke 1874 (nomen dubium) = (possibly) Ischyrosaurus manseli, Ornithopsis manseliOrnithopsisOrnithopsis was a medium-sized Early Cretaceous sauropod dinosaur, from England. It has been considered a synonym of the wastebasket taxon Pelorosaurus, but recent research suggests that this is not as clear-cut as supposed...
and Morinosaurus typus - P. humerocristatus (Hulke 1874) Sauvage 1887 = Duriatitan humerocristatusDuriatitanDuriatitan is a genus of titanosauriform sauropod dinosaur that lived in the Late Jurassic in what is now United Kingdom. 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,...
. - P. armatus (Gervais 1852) Lydekker 1889 = Oplosaurus armatusOplosaurusOplosaurus was a genus of sauropod dinosaur from the Barremian-age Lower Cretaceous Wessex Formation of the Isle of Wight, England...
- P. hulkei (Seeley 1870) Lydekker 1889 = Ornithopsis hulkeiOrnithopsisOrnithopsis was a medium-sized Early Cretaceous sauropod dinosaur, from England. It has been considered a synonym of the wastebasket taxon Pelorosaurus, but recent research suggests that this is not as clear-cut as supposed...
- P. leedsii (Hulke 1887) Lydekker 1890 (nomen dubium) = Ornithopsis leedsiiOrnithopsisOrnithopsis was a medium-sized Early Cretaceous sauropod dinosaur, from England. It has been considered a synonym of the wastebasket taxon Pelorosaurus, but recent research suggests that this is not as clear-cut as supposed...
- P. praecursor (Sauvage 1876) Sauvage 1895 = Neosodon praecursor
- P. mackesoni (Owen 1884) Steel 1970 (nomen dubium) = Dinodocus mackesoni
- P. megalonyx (Seeley 1869) Olshevsky 1991 (nomen dubium) = Gigantosaurus megalonyxGigantosaurusGigantosaurus is a poorly known sauropod dinosaur genus from England. The type species, Gigantosaurus megalonyx, was named and described by Harry Govier Seeley in 1869...
Phylogeny
Mantell was the first to suggest a relationship between Pelorosaurus and dinosaurs. In 1852 Friedrich August Quenstedt formally listed it in the Dinosauria. Predictably, Owen at first rejected this classification, still in 1859 considering it a member of the CrocodiliaCrocodilia
Crocodilia is an order of large reptiles that appeared about 84 million years ago in the late Cretaceous Period . They are the closest living relatives of birds, as the two groups are the only known survivors of the Archosauria...
.
In 1882 Henri-Émile Sauvage first stated it belonged to the Sauropoda
Sauropoda
Sauropoda , or the sauropods , are an infraorder of saurischian dinosaurs. They had long necks, long tails, small heads , and thick, pillar-like legs. They are notable for the enormous sizes attained by some species, and the group includes the largest animals to have ever lived on land...
. 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
Brachiosaurus
Brachiosaurus is a genus of sauropod dinosaur from the Jurassic Morrison Formation of North America. It was first described by Elmer S. Riggs in 1903 from fossils found in the Grand River Canyon of western Colorado, in the United States. Riggs named the dinosaur Brachiosaurus altithorax,...
, placing Pelorosaurus in the Brachiosaurinae. The genus was subsequently commonly considered a member of Brachiosauridae
Brachiosauridae
Brachiosauridae are a family of dinosaurs, whose members are known as brachiosaurids. They were herbivorous quadrupeds with longer forelegs than hind legs - the name derives from the Greek for arm lizard - and long necks...
. 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
Taxon
|thumb|270px|[[African elephants]] form a widely-accepted taxon, the [[genus]] LoxodontaA taxon is a group of organisms, which a taxonomist adjudges to be a unit. Usually a taxon is given a name and a rank, although neither is a requirement...
, prevents any firm conclusion to be reached, however. In recent years, the material was commonly placed in a more general Titanosauriformes.