Oplosaurus
Encyclopedia
Oplosaurus 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.
Thomas Wright
reported the find of a large reptilian tooth from the Wealden Clay near Brixton Bay on Wight. Wright had presented the find to several experts, among them Richard Owen
, David Forbes, George Robert Waterhouse
and Samuel Pickworth Woodward
but only Gideon Mantell
came with a useful suggestion pointing to a similarity with the teeth of the dinosaur Hylaeosaurus
. Not convinced by this, Wright concluded that the tooth, in view of its sharpness, belonged to a carnivorous reptile of unknown affinities.
Wright had also asked the French paleontologist Paul Gervais
for his opinion on the fossil. Gervais in 1852 based the type species
Oplosaurus armatus on it. The generic name would normally read as "armoured lizard" from the Greek hoplon, "body armour". The usual story about the — given the fact that Oplosaurus is not known to be armoured — odd choice of name is that Gervais named this large, well-preserved tooth (holotype
BMNH R964) under the mistaken belief that its owner was an armoured dinosaur like Hylaeosaurus following Mantell's suggestion. However, recent research by Ben Creisler shows that Gervais compared it to Mosasaurus
, not Hylaeosaurus, and that the name may have been intended as "armed lizard", with the teeth as the weapons of a carnivore
, as hoplon can also mean "weapon" (although this would make the specific name redundant, as armatus too means "armed" in Latin
).
Richard Lydekker
(1888) suggested that a maxilla
with a tooth (BMNH R751), also from the Isle of Wight, was another exemplar of this animal, but this opinion has not been substantiated. Lydekker also used the improved spelling "Hoplosaurus" but the original Oplosaurus has priority.
The tooth is large, 85 mm (3.35 in) tall in total, with a spatula
te crown 52 mm (2.05 in) tall, comparable to Brachiosaurus
; it has a pointed tip, a slightly compressed form "cheek" to tongue
, a slight convexity to the base of the tongue-facing side, and wear facets. It is vaguely like a Brachiosaurus tooth, which is why the genus has for a time been referred to the Brachiosauridae
. Earlier, Oplosaurus was typically referred to Pelorosaurus
following an opinion of Friedrich von Huene
in 1909, although Pelorosaurus is based on fragmentary remains that do not include teeth, making it impossible to prove the identity. (See Naish and Martill (2001) for a good review of Oplosaurus and Wealden
sauropods in general; here is a more recent informal summation of the state of work.)
Given how poor the Pelorosaurus
holotype
material is, and that it doesn't include teeth, recent reviews have retained Oplosaurus as a potentially valid but poorly-known genus. Darren Naish
, a British
palaeontologist familiar with Wealden sauropods, has suggested informally that the genus may be a turiasaur
but also co-authored an article concluding it was a member of the Camarasauridae. In any case, it likely belongs to the more general Macronaria
.
, indicating that the owner was a large sauropod; as a possible turiasaur, the size should not change drastically. It would have been a quadruped
al herbivore
, possibly around 25 m (82 ft) long.
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
of sauropod dinosaur
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...
from the Barremian
Barremian
The Barremian is an age in the geologic timescale between 130.0 ± 1.5 Ma and 125.0 ± 1.0 Ma). It is a subdivision of the Early Cretaceous epoch...
-age Lower Cretaceous Wessex Formation
Wessex Formation
The Wessex Formation is an English fossil site and geological formation that dates to the Barremian stage of the Early Cretaceous. It is part of the Wealden Group and underlies the younger Vectis Formation.-Invertebrates:...
of 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...
, 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...
. It is known from a single tooth usually referred to the contemporaneous "wastebasket taxon" Pelorosaurus
Pelorosaurus
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...
, although there is no solid evidence for this.
History and Taxonomy
In 1852 geologistGeologist
A geologist is a scientist who studies the solid and liquid matter that constitutes the Earth as well as the processes and history that has shaped it. Geologists usually engage in studying geology. Geologists, studying more of an applied science than a theoretical one, must approach Geology using...
Thomas Wright
Thomas Wright (geologist)
Thomas Wright was a Scottish surgeon and palaeontologist.Wright published a number of papers on the fossils which he had collected in the Cotswolds, including Lias Ammonites of the British Isles....
reported the find of a large reptilian tooth from the Wealden Clay near Brixton Bay on Wight. Wright had presented the find to several experts, among them Richard Owen
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...
, David Forbes, George Robert Waterhouse
George Robert Waterhouse
George Robert Waterhouse was an English naturalist.In 1833, Waterhouse was elected as the Royal Entomological Society of London's librarian and curator of insects and records....
and Samuel Pickworth Woodward
Samuel Pickworth Woodward
Samuel Pickworth Woodward was an English geologist.A son of the geologist Samuel Woodward, S. P. Woodward became in 1845 professor of geology and natural history in the Royal Agricultural College, Cirencester, and in 1848 was appointed assistant in the department of geology and mineralogy in the...
but only Gideon Mantell
Gideon Mantell
Gideon Algernon Mantell MRCS FRS was an English obstetrician, geologist and palaeontologist...
came with a useful suggestion pointing to a similarity with the teeth of the dinosaur Hylaeosaurus
Hylaeosaurus
Hylaeosaurus is the most obscure of the three animals used by Sir Richard Owen to first define the new group Dinosauria, in 1842. The original specimen, recovered by Gideon Mantell from the Tilgate Forest in the south of England in 1832, now resides in the Natural History Museum of London, where...
. Not convinced by this, Wright concluded that the tooth, in view of its sharpness, belonged to a carnivorous reptile of unknown affinities.
Wright had also asked the French paleontologist Paul Gervais
Paul Gervais
For the Canadian parliamentarian see Paul Mullins GervaisPaul Gervais full name François Louis Paul Gervaise was a French palaeontologist and entomologist.-Biography:...
for his opinion on the fossil. Gervais in 1852 based 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...
Oplosaurus armatus on it. The generic name would normally read as "armoured lizard" from the Greek hoplon, "body armour". The usual story about the — given the fact that Oplosaurus is not known to be armoured — odd choice of name is that Gervais named this large, well-preserved tooth (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...
BMNH R964) under the mistaken belief that its owner was an armoured dinosaur like Hylaeosaurus following Mantell's suggestion. However, recent research by Ben Creisler shows that Gervais compared it to Mosasaurus
Mosasaurus
Mosasaurus is a genus of mosasaur, carnivorous, aquatic lizards, somewhat resembling flippered crocodiles, with elongated heavy jaws. The genus existed during the Maastrichtian age of the Cretaceous period , around 70-65 millions years ago in the area of modern Western Europe and North America...
, not Hylaeosaurus, and that the name may have been intended as "armed lizard", with the teeth as the weapons of a carnivore
Carnivore
A carnivore meaning 'meat eater' is an organism that derives its energy and nutrient requirements from a diet consisting mainly or exclusively of animal tissue, whether through predation or scavenging...
, as hoplon can also mean "weapon" (although this would make the specific name redundant, as armatus too means "armed" in Latin
Latin
Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...
).
Richard Lydekker
Richard Lydekker
Richard Lydekker was an English naturalist, geologist and writer of numerous books on natural history.-Biography:...
(1888) suggested that a maxilla
Maxilla
The maxilla is a fusion of two bones along the palatal fissure that form the upper jaw. This is similar to the mandible , which is also a fusion of two halves at the mental symphysis. Sometimes The maxilla (plural: maxillae) is a fusion of two bones along the palatal fissure that form the upper...
with a tooth (BMNH R751), also from the Isle of Wight, was another exemplar of this animal, but this opinion has not been substantiated. Lydekker also used the improved spelling "Hoplosaurus" but the original Oplosaurus has priority.
The tooth is large, 85 mm (3.35 in) tall in total, with a spatula
Spatula
The term spatula is used to refer to various small implements with a broad, flat, flexible blade used to mix, spread and lift materials including foods, drugs, plaster and paints...
te crown 52 mm (2.05 in) tall, comparable to 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,...
; it has a pointed tip, a slightly compressed form "cheek" to tongue
Tongue
The tongue is a muscular hydrostat on the floors of the mouths of most vertebrates which manipulates food for mastication. It is the primary organ of taste , as much of the upper surface of the tongue is covered in papillae and taste buds. It is sensitive and kept moist by saliva, and is richly...
, a slight convexity to the base of the tongue-facing side, and wear facets. It is vaguely like a Brachiosaurus tooth, which is why the genus has for a time been referred to the 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...
. Earlier, Oplosaurus was typically referred to Pelorosaurus
Pelorosaurus
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...
following an opinion of 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 1909, although Pelorosaurus is based on fragmentary remains that do not include teeth, making it impossible to prove the identity. (See Naish and Martill (2001) for a good review of Oplosaurus and Wealden
Wealden
For the stone, see Wealden GroupWealden is a local government district in East Sussex, England: its name comes from the Weald, the area of high land which occupies the centre of its area.-History:...
sauropods in general; here is a more recent informal summation of the state of work.)
Given how poor the Pelorosaurus
Pelorosaurus
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...
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...
material is, and that it doesn't include teeth, recent reviews have retained Oplosaurus as a potentially valid but poorly-known genus. Darren 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...
, a British
United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...
palaeontologist familiar with Wealden sauropods, has suggested informally that the genus may be a turiasaur
Turiasaurus
Turiasaurus is a genus of sauropod dinosaur from the Jurassic-Cretaceous boundary...
but also co-authored an article concluding it was a member of the Camarasauridae. In any case, it likely belongs to the more general Macronaria
Macronaria
Macronaria is a clade of sauropod dinosaurs from the Middle Jurassic to Late Cretaceous Periods of what are now North America, South America, Europe, Asia and Africa. The name means 'large nostrils' , in reference to the large nasal openings high on the head that probably supported fleshy...
.
Paleobiology
As Naish and Martill point out, the tooth is comparable in size to that of BrachiosaurusBrachiosaurus
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,...
, indicating that the owner was a large sauropod; as a possible turiasaur, the size should not change drastically. It would have been a quadruped
Quadruped
Quadrupedalism is a form of land animal locomotion using four limbs or legs. An animal or machine that usually moves in a quadrupedal manner is known as a quadruped, meaning "four feet"...
al herbivore
Herbivore
Herbivores are organisms that are anatomically and physiologically adapted to eat plant-based foods. Herbivory is a form of consumption in which an organism principally eats autotrophs such as plants, algae and photosynthesizing bacteria. More generally, organisms that feed on autotrophs in...
, possibly around 25 m (82 ft) long.