Megalosaurus Cuvieri
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''Megalosaurus'' (meaning "great lizard", from
Greek Greek may refer to: Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group *Greek language, a branch of the Indo-European language family **Proto-Greek language, the assumed last common ancestor of all kno ...
, ', meaning 'big', 'tall' or 'great' and , ', meaning 'lizard') is an extinct
genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...
of large carnivorous
theropod Theropoda (; from ancient Greek , (''therion'') "wild beast"; , (''pous, podos'') "foot"">wiktionary:ποδός"> (''pous, podos'') "foot" is one of the three major groups (clades) of dinosaurs, alongside Ornithischia and Sauropodom ...
dinosaur Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic Geological period, period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the #Evolutio ...
s of the Middle
Jurassic The Jurassic ( ) is a Geological period, geologic period and System (stratigraphy), stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately 143.1 Mya. ...
Epoch In chronology and periodization, an epoch or reference epoch is an instant in time chosen as the origin of a particular calendar era. The "epoch" serves as a reference point from which time is measured. The moment of epoch is usually decided b ...
(
Bathonian In the geologic timescale the Bathonian is an age (geology), age and stage (stratigraphy), stage of the Middle Jurassic. It lasted from approximately 168.2 ±1.2 annum, Ma to around 165.3 ±1.1 Ma (million years ago). The Bathonian Age succeeds ...
stage, 166 million years ago) of southern
England England is a Countries of the United Kingdom, country that is part of the United Kingdom. It is located on the island of Great Britain, of which it covers about 62%, and List of islands of England, more than 100 smaller adjacent islands. It ...
. Although fossils from other areas have been assigned to the genus, the only certain remains of ''Megalosaurus'' come from
Oxfordshire Oxfordshire ( ; abbreviated ''Oxon'') is a ceremonial county in South East England. The county is bordered by Northamptonshire and Warwickshire to the north, Buckinghamshire to the east, Berkshire to the south, and Wiltshire and Glouceste ...
and date to the late
Middle Jurassic The Middle Jurassic is the second Epoch (geology), epoch of the Jurassic Period (geology), Period. It lasted from about 174.1 to 161.5 million years ago. Fossils of land-dwelling animals, such as dinosaurs, from the Middle Jurassic are relativel ...
. The earliest remains of ''Megalosaurus'' were described in the 17th century, and were initially interpreted as the remains of elephants or giants. ''Megalosaurus'' was named in 1824 by
William Buckland William Buckland Doctor of Divinity, DD, Royal Society, FRS (12 March 1784 – 14 August 1856) was an English theologian, geologist and paleontology, palaeontologist. His work in the early 1820s proved that Kirkdale Cave in North Yorkshire h ...
, becoming the first genus of (non-avian) dinosaur to be validly named. The
type species In International_Code_of_Zoological_Nomenclature, zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the spe ...
is ''M. bucklandii'', named in 1827 by
Gideon Mantell Gideon Algernon Mantell Membership of the Royal College of Surgeons, MRCS Fellow of the Royal Society, FRS (3 February 1790 – 10 November 1852) was an English obstetrician, geologist and paleontology, palaeontologist. His attempts to reconstr ...
, after Buckland. In 1842, ''Megalosaurus'' was one of three genera on which
Richard Owen Sir Richard Owen (20 July 1804 – 18 December 1892) was an English biologist, comparative anatomy, comparative anatomist and paleontology, palaeontologist. Owen is generally considered to have been an outstanding naturalist with a remarkabl ...
based his Dinosauria, along with ''
Iguanodon ''Iguanodon'' ( ; meaning 'iguana-tooth'), named in 1825, is a genus of iguanodontian dinosaur. While many species found worldwide have been classified in the genus ''Iguanodon'', dating from the Late Jurassic to Early Cretaceous, Taxonomy (bi ...
'' and ''
Hylaeosaurus ''Hylaeosaurus'' ( ; Greek: / "belonging to the forest" and / "lizard") is a herbivorous ankylosaurian dinosaur that lived about 136 million years ago, in the late Valanginian stage of the early Cretaceous period of England. It was found i ...
''. On Owen's directions a model was made as one of the
Crystal Palace Dinosaurs The Crystal Palace Dinosaurs are a series of sculptures of dinosaurs and other extinct animals in the London borough of Bromley's Crystal Palace Park. Commissioned in 1852 to accompany the Crystal Palace after its move from the Great Exhi ...
, which greatly increased the public interest for prehistoric reptiles. Over 50 other species would eventually be classified under the genus; at first, this was because so few types of dinosaur had been identified, but the practice continued even into the 20th century after many other dinosaurs had been discovered. Today it is understood that none of these additional species was directly related to ''M. bucklandii'', which is the only true ''Megalosaurus'' species. Because a complete skeleton of it has never been found, much is still unclear about its build. The first naturalists who investigated ''Megalosaurus'' mistook it for a gigantic lizard in length. In 1842, Owen concluded that it was no longer than . He still thought it was a quadruped, though. Modern scientists were able to obtain a more accurate picture, by comparing ''Megalosaurus'' with its direct relatives in the
Megalosauridae Megalosauridae is a monophyletic Family (taxonomy), family of Carnivore, carnivorous theropod dinosaurs within the group Megalosauroidea. Appearing in the Middle Jurassic, megalosaurids were among the first major radiation of large theropod dino ...
. ''Megalosaurus'' was about long, weighing about . It was bipedal, walking on stout hindlimbs, its horizontal torso balanced by a horizontal tail. Its forelimbs were short, though very robust. ''Megalosaurus'' had a rather large head, equipped with long curved teeth. It was generally a robust and heavily muscled animal. At the time ''Megalosaurus'' lived, Europe formed an island
archipelago An archipelago ( ), sometimes called an island group or island chain, is a chain, cluster, or collection of islands. An archipelago may be in an ocean, a sea, or a smaller body of water. Example archipelagos include the Aegean Islands (the o ...
bounded by then narrow
Atlantic Ocean The Atlantic Ocean is the second largest of the world's five borders of the oceans, oceanic divisions, with an area of about . It covers approximately 17% of Earth#Surface, Earth's surface and about 24% of its water surface area. During the ...
and
Tethys Ocean The Tethys Ocean ( ; ), also called the Tethys Sea or the Neo-Tethys, was a prehistoric ocean during much of the Mesozoic Era and early-mid Cenozoic Era. It was the predecessor to the modern Indian Ocean, the Mediterranean Sea, and the Eurasia ...
, with ''Megalosaurus'' inhabiting an island formed by the
London–Brabant Massif The London–Brabant Massif or London–Brabant Platform is, in the tectonic structure of Europe, a structural high or massif that stretches from the Rhineland in western Germany across northern Belgium (in the province of Brabant) and the North S ...
, where it likely served as the
apex predator An apex predator, also known as a top predator or superpredator, is a predator at the top of a food chain, without natural predators of its own. Apex predators are usually defined in terms of trophic dynamics, meaning that they occupy the hig ...
of its ecosystem, coexisting with other dinosaurs like the large sauropod ''
Cetiosaurus ''Cetiosaurus'' ( meaning 'whale lizard', from the Greek '/ meaning 'sea monster' (later, 'whale') and '/ meaning 'lizard'), is a genus of herbivorous sauropod dinosaur from the Middle Jurassic Period, living about 171 to 165 million years ago ...
,''
stegosaurs Stegosauria is a group of Herbivore, herbivorous ornithischian dinosaurs that lived during the Jurassic and early Cretaceous Period (geology), periods. Stegosaurian fossils have been found mostly in the Northern Hemisphere (North America, Europe a ...
,
ankylosaurs Ankylosauria is a group of herbivorous dinosaurs of the clade Ornithischia. It includes the great majority of dinosaurs with Armour (zoology), armor in the form of bony osteoderms, similar to turtles. Ankylosaurs were bulky quadrupeds, with short ...
, and
heterodontosaurids Heterodontosauridae is a family (biology), family of ornithischian dinosaurs that were likely among the most Basal (phylogenetics), basal (primitive) members of the group. Their phylogenetic placement is uncertain but they are most commonly fou ...
.


Discovery and naming


Edward Lhuyd's tooth (specimen OU 1328)

In 1699,
Edward Lhuyd Edward Lhuyd (1660– 30 June 1709), also known as Edward Lhwyd and by other spellings, was a Welsh scientist, geographer, historian and antiquary. He was the second Keeper of the University of Oxford's Ashmolean Museum, and published the firs ...
described what he believed to have been a
fish A fish (: fish or fishes) is an aquatic animal, aquatic, Anamniotes, anamniotic, gill-bearing vertebrate animal with swimming fish fin, fins and craniate, a hard skull, but lacking limb (anatomy), limbs with digit (anatomy), digits. Fish can ...
tooth (called ''Plectronites''), later believed to be part of a
belemnite Belemnitida (or belemnites) is an extinct order (biology), order of squid-like cephalopods that existed from the Late Triassic to Late Cretaceous (And possibly the Eocene). Unlike squid, belemnites had an internal skeleton that made up the cone ...
, that was illustrated alongside the holotype
tooth A tooth (: teeth) is a hard, calcified structure found in the jaws (or mouths) of many vertebrates and used to break down food. Some animals, particularly carnivores and omnivores, also use teeth to help with capturing or wounding prey, tea ...
of the
sauropod Sauropoda (), whose members are known as sauropods (; from '' sauro-'' + '' -pod'', 'lizard-footed'), is a clade of saurischian ('lizard-hipped') dinosaurs. Sauropods had very long necks, long tails, small heads (relative to the rest of their b ...
"
Rutellum This list of informally named dinosaurs is a listing of dinosaurs (excluding Aves; birds and their extinct relatives) that have never been given formally published scientific names. This list only includes names that were not properly published ...
impicatum" and another tooth, from a
theropod Theropoda (; from ancient Greek , (''therion'') "wild beast"; , (''pous, podos'') "foot"">wiktionary:ποδός"> (''pous, podos'') "foot" is one of the three major groups (clades) of dinosaurs, alongside Ornithischia and Sauropodom ...
, in 1699.Lhuyd, E. (1699).
Lithophylacii Britannici Ichnographia, sive lapidium aliorumque fossilium Britannicorum singulari figura insignium
'. Gleditsch and Weidmann:London.
Later studies found that the theropod tooth, known as specimen 1328 (
University of Oxford The University of Oxford is a collegiate university, collegiate research university in Oxford, England. There is evidence of teaching as early as 1096, making it the oldest university in the English-speaking world and the List of oldest un ...
coll. #1328; lost?) almost certainly was a tooth crown that belonged to an unknown species of ''Megalosaurus''.Delair, J.B., and Sarjeant, W.A.S. (2002)
The earliest discoveries of dinosaurs: the records re-examined
''Proceedings of the Geologists' Association'' 113:185–197.
OU 1328 has since been lost and it was not confidently assigned to ''Megalosaurus'' until the tooth was re-described by Delair & Sarjeant (2002). OU 1328 was collected near Caswell, near
Witney Witney is a market town on the River Windrush in West Oxfordshire in the county of Oxfordshire, England. It is west of Oxford. History The Toponymy, place-name "Witney" is derived from the Old English for "Witta's island". The earliest kno ...
,
Oxfordshire Oxfordshire ( ; abbreviated ''Oxon'') is a ceremonial county in South East England. The county is bordered by Northamptonshire and Warwickshire to the north, Buckinghamshire to the east, Berkshire to the south, and Wiltshire and Glouceste ...
sometime during the 17th century and became the third dinosaur fossil to ever be illustrated,Gunther, R.T. (1945). ''Early Science in Oxford: Life and Letters of Edward Lhuyd'', volume 14. Author:Oxford. after "Scrotum humanum" in 1677 and "Rutellum impicatum" in 1699.


"Scrotum humanum"

''Megalosaurus'' may have been the first non avian
dinosaur Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic Geological period, period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the #Evolutio ...
to be described in the scientific literature. The earliest possible fossil of the genus, from the
Taynton Limestone Formation The Taynton LimestoneWeishampel, David B; et al. (2004). "Dinosaur distribution (Middle Jurassic, Europe)." In: Weishampel, David B.; Dodson, Peter; and Osmólska, Halszka (eds.): The Dinosauria, 2nd, Berkeley: University of California Press. Pp. ...
, was the lower part of a
femur The femur (; : femurs or femora ), or thigh bone is the only long bone, bone in the thigh — the region of the lower limb between the hip and the knee. In many quadrupeds, four-legged animals the femur is the upper bone of the hindleg. The Femo ...
, discovered in the 17th century. Part of a bone was recovered from the Taynton Limestone Formation of
Stonesfield Stonesfield is a village and civil parish about north of Witney in Oxfordshire, and about 10 miles (17 km) north-west of Oxford. The village is on the crest of an escarpment. The parish extends mostly north and north-east of the village, ...
limestone quarry,
Oxfordshire Oxfordshire ( ; abbreviated ''Oxon'') is a ceremonial county in South East England. The county is bordered by Northamptonshire and Warwickshire to the north, Buckinghamshire to the east, Berkshire to the south, and Wiltshire and Glouceste ...
in 1676. Sir Thomas Pennyson gave the fragment to naturalist
Robert Plot Robert Plot (13 December 1640 – 30 April 1696) was an English naturalist and antiquarian who was the first professor of chemistry at the University of Oxford and the first keeper of the Ashmolean Museum. Early life and education Born in Bor ...
, who published a description and illustration in his ''Natural History of Oxfordshire'' in 1676. It was the first illustration of a dinosaur bone published. Plot correctly identified the bone as the lower extremity of the
thighbone The femur (; : femurs or femora ), or thigh bone is the only bone in the thigh — the region of the lower limb between the hip and the knee. In many four-legged animals the femur is the upper bone of the hindleg. The top of the femur fits i ...
or
femur The femur (; : femurs or femora ), or thigh bone is the only long bone, bone in the thigh — the region of the lower limb between the hip and the knee. In many quadrupeds, four-legged animals the femur is the upper bone of the hindleg. The Femo ...
of a large animal and he recognized that it was too large to belong to any species known to be living in England. He therefore at first concluded it to be the thigh bone of a Roman war elephant and later that of a giant human, such as those mentioned in the Bible. The bone has since been lost, but the illustration is detailed enough that some have since identified it as that of ''Megalosaurus''. It has also been argued that this possible ''Megalosaurus'' bone was given the very first
species name In taxonomy, binomial nomenclature ("two-term naming system"), also called binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, both of which use Latin grammatical forms, altho ...
ever applied to an extinct dinosaur. Plot's engraving of the Cornwell bone was again used in a book by
Richard Brookes Richard Brookes (fl. 1721 – 1763) was an English physician and author of compilations and translations on medicine, surgery, natural history, and geography, most of which went through several editions. Life He was at one time a rural practi ...
in 1763. Brookes, in a caption, called it "
Scrotum In most terrestrial mammals, the scrotum (: scrotums or scrota; possibly from Latin ''scortum'', meaning "hide" or "skin") or scrotal sac is a part of the external male genitalia located at the base of the penis. It consists of a sac of skin ...
humanum", apparently comparing its appearance to a pair of "human
testicle A testicle or testis ( testes) is the gonad in all male bilaterians, including humans, and is Homology (biology), homologous to the ovary in females. Its primary functions are the production of sperm and the secretion of Androgen, androgens, p ...
s". However, it is possible that the attribution of this name stemmed from illustrator error, not Richard Brookes. In 1970, paleontologist Lambert Beverly Halstead pointed out that the similarity of ''Scrotum humanum'' to a modern species name, a so-called Linnaean "
binomen In taxonomy, binomial nomenclature ("two-term naming system"), also called binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, both of which use Latin grammatical forms, altho ...
" that has two parts, was not a coincidence.
Linnaeus Carl Linnaeus (23 May 1707 – 10 January 1778), also known after ennoblement in 1761 as Carl von Linné,#Blunt, Blunt (2004), p. 171. was a Swedish biologist and physician who formalised binomial nomenclature, the modern system of naming o ...
, the founder of modern
taxonomy image:Hierarchical clustering diagram.png, 280px, Generalized scheme of taxonomy Taxonomy is a practice and science concerned with classification or categorization. Typically, there are two parts to it: the development of an underlying scheme o ...
, had in the eighteenth century not merely devised a system for naming living creatures, but also for classifying geological objects. The book by Brookes was all about applying this latter system to curious stones found in England. According to Halstead, Brookes thus had deliberately used
binomial nomenclature In taxonomy, binomial nomenclature ("two-term naming system"), also called binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, both of which use Latin grammatical forms, altho ...
, and had in fact indicated the possible
type specimen In biology, a type is a particular wikt:en:specimen, specimen (or in some cases a group of specimens) of an organism to which the scientific name of that organism is formally associated. In other words, a type is an example that serves to ancho ...
of a new biological genus. According to the rules of the
International Code of Zoological Nomenclature The International Code of Zoological Nomenclature (ICZN) is a widely accepted Convention (norm), convention in zoology that rules the formal scientific name, scientific naming of organisms treated as animals. It is also informally known as the I ...
(ICZN), the name ''Scrotum humanum'' in principle had priority over ''Megalosaurus'' because it was published first. That Brookes understood that the stone did not actually represent a pair of petrified testicles was irrelevant. Merely the fact that the name had not been used in subsequent literature meant that it could be removed from competition for priority, because the ICZN states that if a name has never been considered valid after 1899, it can be made a ''
nomen oblitum In zoological nomenclature, a ''nomen oblitum'' (plural: ''nomina oblita''; Latin for "forgotten name") is a disused scientific name which has been declared to be obsolete (figuratively "forgotten") in favor of another "protected" name. In its pr ...
'', an invalid "forgotten name". In 1993, after the death of Halstead, his friend William A.S. Sarjeant submitted a petition to the
International Commission on Zoological Nomenclature The International Commission on Zoological Nomenclature (ICZN) is an organization dedicated to "achieving stability and sense in the scientific naming of animals". Founded in 1895, it currently comprises 26 commissioners from 20 countries. Orga ...
to formally suppress the name ''Scrotum'' in favour of ''Megalosaurus''. He wrote that the supposed junior synonym ''Megalosaurus bucklandii'' should be made a
conserved name A conserved name or ''nomen conservandum'' (plural ''nomina conservanda'', abbreviated as ''nom. cons.'') is a scientific name that has specific nomenclatural protection. That is, the name is retained, even though it violates one or more rules wh ...
to ensure its priority. However, the Executive Secretary of the ICZN at the time, Philip K. Tubbs, did not consider the petition to be admissible, concluding that the term "Scrotum humanum", published merely as a label for an illustration, did not constitute the valid creation of a new name, and stated that there was no evidence it was ever intended as such. Furthermore, the partial femur was too incomplete to definitely be referred to ''Megalosaurus'' and not a different, contemporary theropod.


Buckland's research

During the last part of the eighteenth century, the number of fossils in British collections quickly increased. According to a hypothesis published by
science historian The history of science and technology (HST) is a field of history that examines the development of the understanding of the natural world (science) and humans' ability to manipulate it (technology) at different points in time. This academic discip ...
Robert Gunther Robert William Theodore Gunther (23 August 1869 – 9 March 1940) was a historian of science, zoologist, and founder of the Museum of the History of Science, Oxford. Gunther's father, Albert Günther, was Keeper of Zoology at the British Mus ...
in 1925, among them was a partial lower jaw of ''Megalosaurus''. It was discovered about underground in a Stonesfield Slate mine during the early 1790s and was acquired in October 1797 by
Christopher Pegge Sir Christopher Pegge M.D. (1765–1822) was an English physician. Life The son of Samuel Pegge the younger, by his first wife, he was born in London. He entered Christ Church, Oxford, as a commoner on 18 April 1782, and graduated B.A. on 23 Fe ...
for 10s.6d. and added to the collection of the Anatomy School of
Christ Church, Oxford Christ Church (, the temple or house, ''wikt:aedes, ædes'', of Christ, and thus sometimes known as "The House") is a Colleges of the University of Oxford, constituent college of the University of Oxford in England. Founded in 1546 by Henry V ...
. In the early nineteenth century, more discoveries were made. In 1815, John Kidd reported the find of bones of giant tetrapods, again at the
Stonesfield Stonesfield is a village and civil parish about north of Witney in Oxfordshire, and about 10 miles (17 km) north-west of Oxford. The village is on the crest of an escarpment. The parish extends mostly north and north-east of the village, ...
quarry. The layers there are currently considered part of the Taynton Limestone Formation, dating to the mid-
Bathonian In the geologic timescale the Bathonian is an age (geology), age and stage (stratigraphy), stage of the Middle Jurassic. It lasted from approximately 168.2 ±1.2 annum, Ma to around 165.3 ±1.1 Ma (million years ago). The Bathonian Age succeeds ...
stage of the
Jurassic The Jurassic ( ) is a Geological period, geologic period and System (stratigraphy), stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately 143.1 Mya. ...
Period. The bones were apparently acquired by
William Buckland William Buckland Doctor of Divinity, DD, Royal Society, FRS (12 March 1784 – 14 August 1856) was an English theologian, geologist and paleontology, palaeontologist. His work in the early 1820s proved that Kirkdale Cave in North Yorkshire h ...
, Professor of Geology at the University of Oxford and fellow of Corpus Christi. Buckland also studied a lower jaw, according to Gunther the one bought by Pegge. Buckland did not know to what animal the bones belonged but, in 1818, after the
Napoleonic Wars {{Infobox military conflict , conflict = Napoleonic Wars , partof = the French Revolutionary and Napoleonic Wars , image = Napoleonic Wars (revision).jpg , caption = Left to right, top to bottom:Battl ...
, the
French French may refer to: * Something of, from, or related to France ** French language, which originated in France ** French people, a nation and ethnic group ** French cuisine, cooking traditions and practices Arts and media * The French (band), ...
comparative anatomist
Georges Cuvier Jean Léopold Nicolas Frédéric, baron Cuvier (23 August 1769 – 13 May 1832), known as Georges Cuvier (; ), was a French natural history, naturalist and zoology, zoologist, sometimes referred to as the "founding father of paleontology". Cuv ...
visited Buckland in Oxford and realized that they were those of a giant
lizard Lizard is the common name used for all Squamata, squamate reptiles other than snakes (and to a lesser extent amphisbaenians), encompassing over 7,000 species, ranging across all continents except Antarctica, as well as most Island#Oceanic isla ...
-like creature. Buckland further studied the remains with Mary Morland (later his wife), and his friend William Conybeare who in 1821 referred to them as the "Huge Lizard". In 1822 Buckland and Conybeare, in a joint article to be included in Cuvier's ''Ossemens'', intended to provide scientific names for both gigantic lizard-like creatures known at the time: the remains found near
Maastricht Maastricht ( , , ; ; ; ) is a city and a Municipalities of the Netherlands, municipality in the southeastern Netherlands. It is the capital city, capital and largest city of the province of Limburg (Netherlands), Limburg. Maastricht is loca ...
would be named ''
Mosasaurus ''Mosasaurus'' (; "lizard of the Meuse (river), Meuse River") is the type genus (defining example) of the mosasaurs, an extinct group of aquatic Squamata, squamate reptiles. It lived from about 82 to 66 million years ago during the Campanian an ...
'' – then seen as a land-dwelling animal – while for the British lizard Conybeare had devised the name "Megalosaurus", from the Greek μέγας, ''megas'', "large". That year a publication failed to occur, but the physician
James Parkinson James Parkinson (11 April 1755 – 21 December 1824) was an English surgeon, apothecary, geologist, palaeontologist and political activist. He is best known for his 1817 work ''An Essay on the Shaking Palsy'', in which he was the first to desc ...
already in 1822 announced the name "Megalosaurus", illustrating one of the teeth and revealing the creature was 40 feet long and eight feet high. It is generally considered that the name in 1822 was still a ''
nomen nudum In Taxonomy (biology), taxonomy, a ''nomen nudum'' ('naked name'; plural ''nomina nuda'') is a designation which looks exactly like a scientific name of an organism, and may have originally been intended to be one, but it has not been published ...
'' ("naked name"). Buckland, urged on by an impatient Cuvier, continued to work on the subject during 1823.
Mary Mary may refer to: People * Mary (name), a female given name (includes a list of people with the name) Religion * New Testament people named Mary, overview article linking to many of those below * Mary, mother of Jesus, also called the Blesse ...
provide drawings of the bones, that were to be the basis of illustrating lithographies. Finally, on 20 February 1824, during the same meeting of the
Geological Society of London The Geological Society of London, known commonly as the Geological Society, is a learned society based in the United Kingdom. It is the oldest national geological society in the world and the largest in Europe, with more than 12,000 Fellows. Fe ...
in which Conybeare described a very complete specimen of ''
Plesiosaurus ''Plesiosaurus'' (Greek: ' ('), near to + ' ('), lizard) is a genus of extinct, large marine sauropterygian reptile that lived during the Early Jurassic. It is known by nearly complete skeletons from the Lias of England. It is distinguishable by ...
'', Buckland formally announced ''Megalosaurus''. The descriptions of the bones in the ''Transactions of the Geological Society'', in 1824, constitute a valid publication of the name. ''Megalosaurus'' was the first non-avian dinosaur genus named; the first of which the remains had with certainty been scientifically described was ''
Streptospondylus ''Streptospondylus'', from Ancient Greek στρεπτός (''streptós''), meaning "twisted", and σπόνδυλος (''spóndulos''), meaning "vertebra", is a genus of tetanuran theropod dinosaur known from the Late Jurassic period of France, 1 ...
'', in 1808 by Cuvier. By 1824, the material available to Buckland consisted of specimen OUM J13505, a piece of a right lower jaw with a single erupted tooth; OUM J13577, a posterior dorsal
vertebra Each vertebra (: vertebrae) is an irregular bone with a complex structure composed of bone and some hyaline cartilage, that make up the vertebral column or spine, of vertebrates. The proportions of the vertebrae differ according to their spina ...
; OUM J13579, an anterior caudal vertebra; OUM J13576, a
sacrum The sacrum (: sacra or sacrums), in human anatomy, is a triangular bone at the base of the spine that forms by the fusing of the sacral vertebrae (S1S5) between ages 18 and 30. The sacrum situates at the upper, back part of the pelvic cavity, ...
of five sacral vertebrae; OUM J13585, a cervical rib; OUM J13580, a rib; OUM J29881, an ilium of the
pelvis The pelvis (: pelves or pelvises) is the lower part of an Anatomy, anatomical Trunk (anatomy), trunk, between the human abdomen, abdomen and the thighs (sometimes also called pelvic region), together with its embedded skeleton (sometimes also c ...
, OUM J13563, a piece of the
pubic bone In vertebrates, the pubis or pubic bone () forms the lower and anterior part of each side of the hip bone. The pubis is the most forward-facing (ventral and anterior) of the three bones that make up the hip bone. The left and right pubic bones ar ...
; OUM J13565, a part of the
ischium The ischium (; : is ...
; OUM J13561, a thigh bone and OUM J13572, the lower part of a second
metatarsal The metatarsal bones or metatarsus (: metatarsi) are a group of five long bones in the midfoot, located between the tarsal bones (which form the heel and the ankle) and the phalanges ( toes). Lacking individual names, the metatarsal bones are ...
. As he himself was aware, these did not all belong to the same individual; only the sacrum was articulated. Because they represented several individuals, the described fossils formed a
syntype In biological nomenclature, a syntype is any one of two or more biological types that is listed in a description of a taxon where no holotype was designated. Precise definitions of this and related terms for types have been established as part o ...
series. By modern standards, from these a single specimen has to be selected to serve as the type specimen on which the name is based. In 1990,
Ralph Molnar Ralph E. Molnar is a paleontologist who had been Curator of Mammals at the Queensland Museum and more recently associated with the Museum of Northern Arizona. He is also a research associate at the Texas Natural Science Centre. He co-authored descr ...
chose the famous
dentary In jawed vertebrates, the mandible (from the Latin ''mandibula'', 'for chewing'), lower jaw, or jawbone is a bone that makes up the lowerand typically more mobilecomponent of the mouth (the upper jaw being known as the maxilla). The jawbone ...
(front part of the lower jaw), OUM J13505, as such a
lectotype In biology, a type is a particular specimen (or in some cases a group of specimens) of an organism to which the scientific name of that organism is formally associated. In other words, a type is an example that serves to anchor or centralizes ...
.Molnar, R.E.; Seriozha M.K. & Dong Z. (1990). "Carnosauria" In: Because he was unaccustomed to the deep dinosaurian pelvis, much taller than with typical reptiles, Buckland misidentified several bones, interpreting the pubic bone as a
fibula The fibula (: fibulae or fibulas) or calf bone is a leg bone on the lateral side of the tibia, to which it is connected above and below. It is the smaller of the two bones and, in proportion to its length, the most slender of all the long bones. ...
and mistaking the ischium for a
clavicle The clavicle, collarbone, or keybone is a slender, S-shaped long bone approximately long that serves as a strut between the scapula, shoulder blade and the sternum (breastbone). There are two clavicles, one on each side of the body. The clavic ...
. Buckland identified the organism as being a giant animal belonging to the
Sauria Sauria is the clade of diapsids containing the most recent common ancestor of Archosauria (which includes crocodilians and birds) and Lepidosauria (which includes squamates and the tuatara), and all its descendants. Since most molecular phyl ...
– the Lizards, at the time seen as including the crocodiles - and he placed it in the new genus ''Megalosaurus'', repeating an estimate by Cuvier that the largest pieces he described, indicated an animal 12 meters long in life.


Etymology

Buckland had not provided a
specific name Specific name may refer to: * in Database management systems, a system-assigned name that is unique within a particular database In taxonomy, either of these two meanings, each with its own set of rules: * Specific name (botany), the two-part (bino ...
, as was not uncommon in the early nineteenth century, when the genus was still seen as the more essential concept. In 1826, Ferdinand von Ritgen gave this dinosaur a complete binomial, ''Megalosaurus conybeari'', which however was not much used by later authors and is now considered a ''nomen oblitum''. A year later, in 1827,
Gideon Mantell Gideon Algernon Mantell Membership of the Royal College of Surgeons, MRCS Fellow of the Royal Society, FRS (3 February 1790 – 10 November 1852) was an English obstetrician, geologist and paleontology, palaeontologist. His attempts to reconstr ...
included ''Megalosaurus'' in his geological survey of southeastern England, and assigned the species its current valid binomial name, ''Megalosaurus bucklandii''. Until recently, the form ''Megalosaurus bucklandi'' was often used, a variant first published in 1832 by
Christian Erich Hermann von Meyer Christian Erich Hermann von Meyer (3 September 1801 – 2 April 1869), known as Hermann von Meyer, was a German palaeontologist. He was awarded the 1858 Wollaston medal by the Geological Society of London. Life He was born in Frankfurt am ...
– and sometimes erroneously ascribed to von Ritgen – but the more original ''M. bucklandii'' has priority.


Early reconstructions

The first reconstruction was given by Buckland himself. He considered ''Megalosaurus'' to be a quadruped. He thought it was an "amphibian", i.e. an animal capable of both swimming in the sea and walking on land. Generally, in his mind ''Megalosaurus'' resembled a gigantic lizard, but Buckland already understood from the form of the thigh bone head that the legs were not so much sprawling as held rather upright. In the original description of 1824, Buckland repeated Cuvier's size estimate that ''Megalosaurus'' would have been 40 feet long with the weight of a seven foot tall elephant. However, this had been based on the remains present at Oxford. Buckland had also been hurried into naming his new reptile by a visit he had made to the fossil collection of Mantell, who during the lecture announced to have acquired a fossil thigh bone of enormous magnitude, twice as long as that just described. Today, this is known to have belonged to ''
Iguanodon ''Iguanodon'' ( ; meaning 'iguana-tooth'), named in 1825, is a genus of iguanodontian dinosaur. While many species found worldwide have been classified in the genus ''Iguanodon'', dating from the Late Jurassic to Early Cretaceous, Taxonomy (bi ...
'', or at least some iguanodontid, but at the time both men assumed this bone belonged to ''Megalosaurus'' also. Even taking into account the effects of
allometry Allometry (Ancient Greek "other", "measurement") is the study of the relationship of body size to shape, anatomy, physiology and behaviour, first outlined by Otto Snell in 1892, by D'Arcy Thompson in 1917 in ''On Growth and Form'' and by Jul ...
, heavier animals having relatively stouter bones, Buckland was forced in the printed version of his lecture to estimate the maximum length of ''Megalosaurus'' at 60 to 70 feet. The existence of ''Megalosaurus'' posed some problems for Christian
orthodoxy Orthodoxy () is adherence to a purported "correct" or otherwise mainstream- or classically-accepted creed, especially in religion. Orthodoxy within Christianity refers to acceptance of the doctrines defined by various creeds and ecumenical co ...
, which typically held that suffering and death had only come into the world through
Original Sin Original sin () in Christian theology refers to the condition of sinfulness that all humans share, which is inherited from Adam and Eve due to the Fall of man, Fall, involving the loss of original righteousness and the distortion of the Image ...
, which seemed irreconcilable with the presence of a gigantic devouring reptile during a pre-Adamitic phase of history. Buckland rejected the usual solution, that such carnivores would originally have been peaceful vegetarians, as infantile and claimed in one of the ''
Bridgewater Treatises The Bridgewater Treatises (1833–36) are a series of eight works that were written by leading scientific figures appointed by the President of the Royal Society in fulfilment of a bequest of £8000, made by Francis Henry Egerton, 8th Earl of Bridg ...
'' that ''Megalosaurus'' had played a beneficial role in creation by ending the lives of old and ill animals, "to diminish the aggregate amount of animal suffering". Around 1840, it became fashionable in England to espouse the concept of the
transmutation of species The Transmutation of species and transformism are 18th and early 19th-century ideas about the change of one species into another that preceded Charles Darwin's theory of evolution through natural selection. The French ''Transformisme'' was a ter ...
as part of a general progressive development through time, as expressed in the work of Robert Chambers. In reaction, on 2 August 1841
Richard Owen Sir Richard Owen (20 July 1804 – 18 December 1892) was an English biologist, comparative anatomy, comparative anatomist and paleontology, palaeontologist. Owen is generally considered to have been an outstanding naturalist with a remarkabl ...
during a lecture to the
British Association for the Advancement of Science The British Science Association (BSA) is a Charitable organization, charity and learned society founded in 1831 to aid in the promotion and development of science. Until 2009 it was known as the British Association for the Advancement of Scienc ...
claimed that certain prehistoric reptilian groups had already attained the organisational level of present mammals, implying there had been no progress. Owen presented three examples of such higher level reptiles: ''
Iguanodon ''Iguanodon'' ( ; meaning 'iguana-tooth'), named in 1825, is a genus of iguanodontian dinosaur. While many species found worldwide have been classified in the genus ''Iguanodon'', dating from the Late Jurassic to Early Cretaceous, Taxonomy (bi ...
'', ''
Hylaeosaurus ''Hylaeosaurus'' ( ; Greek: / "belonging to the forest" and / "lizard") is a herbivorous ankylosaurian dinosaur that lived about 136 million years ago, in the late Valanginian stage of the early Cretaceous period of England. It was found i ...
'' and ''Megalosaurus''. For these, the "lizard model" was entirely abandoned: they would have had an upright stance and a high metabolism. This also meant that earlier size estimates had been exaggerated. By simply adding the known length of the vertebrae, instead of extrapolating from a lizard, Owen arrived at a total body length for ''Megalosaurus'' of 30 feet. In the printed version of the lecture published in 1842, Owen united the three reptiles into a separate group: the Dinosauria. ''Megalosaurus'' was thus one of the three original dinosaurs. In 1852,
Benjamin Waterhouse Hawkins Benjamin Waterhouse Hawkins (8 February 1807 – 27 January 1894) was an English sculptor and natural history artist renowned for his work on the life-size models of dinosaurs in the Crystal Palace Park in south London. The models, accurately ...
was commissioned to build a life-sized concrete model of ''Megalosaurus'' for the exhibition of prehistoric animals at the Crystal Palace Park in Sydenham, where it remains to this day. Hawkins worked under the direction of Owen and the statue reflected Owen's ideas that ''Megalosaurus'' would have been a mammal-like quadruped. The sculpture in Crystal Palace Park shows a conspicuous hump on the shoulders and it has been suggested this was inspired by a set of high vertebral spines acquired by Owen in the early 1850s. Today, they are seen as a separate genus '' Becklespinax'', but Owen referred them to ''Megalosaurus''. The models at the exhibition created a general public awareness for the first time, at least in England, that ancient reptiles had existed. The presumption that carnivorous dinosaurs, like ''Megalosaurus'', were quadrupeds was first challenged by the find of ''
Compsognathus ''Compsognathus'' (; Ancient Greek, Greek ''kompsos''/κομψός; "elegant", "refined" or "dainty", and ''gnathos''/γνάθος; "jaw") is a genus of small, bipedalism, bipedal, carnivore, carnivorous theropoda, theropod dinosaur. Members o ...
'' in 1859. That, however, was a very small animal, the significance of which for gigantic forms could be denied. In 1870, near Oxford, the type specimen of ''
Eustreptospondylus ''Eustreptospondylus'' ( ;), from Ancient Greek εὖ (''eû''), meaning "well", στρεπτός (''streptós''), meaning "twisted", and σπόνδυλος (''spóndulos''), meaning "vertebra", is a genus of megalosaurid theropod dinosaur, ...
'' was discovered – the first reasonably intact skeleton of a large theropod. It was clearly bipedal. Shortly afterwards, John Phillips created the first public display of a theropod skeleton in Oxford, arranging the known ''Megalosaurus'' bones, held by recesses in cardboard sheets, in a more or less natural position. During the 1870s,
North America North America is a continent in the Northern Hemisphere, Northern and Western Hemisphere, Western hemispheres. North America is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South Ameri ...
n discoveries of large theropods, like ''Allosaurus'', confirmed that they were bipedal. The
Oxford University Museum of Natural History The Oxford University Museum of Natural History (OUMNH) is a museum displaying many of the University of Oxford's natural history specimens, located on Parks Road in Oxford, England. It also contains a lecture theatre which is used by the univers ...
display contains most of the specimens from the original description by Buckland.


Later finds of ''Megalosaurus bucklandii''

The quarries at
Stonesfield Stonesfield is a village and civil parish about north of Witney in Oxfordshire, and about 10 miles (17 km) north-west of Oxford. The village is on the crest of an escarpment. The parish extends mostly north and north-east of the village, ...
, which were worked until 1911, continued to produce ''Megalosaurus bucklandii'' fossils, mostly single bones from the
pelvis The pelvis (: pelves or pelvises) is the lower part of an Anatomy, anatomical Trunk (anatomy), trunk, between the human abdomen, abdomen and the thighs (sometimes also called pelvic region), together with its embedded skeleton (sometimes also c ...
and
hindlimb A hindlimb or back limb is one of the paired articulated appendages ( limbs) attached on the caudal ( posterior) end of a terrestrial tetrapod vertebrate's torso.http://www.merriam-webster.com/medical/hind%20limb, Merriam Webster Dictionary-H ...
s. Vertebrae and skull bones are rare. In 2010, Roger Benson counted a total of 103 specimens from the Stonesfield Slate, from a minimum of seven individuals. It has been contentious whether this material represents just a single
taxon In biology, a taxon (back-formation from ''taxonomy''; : taxa) is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit. Although neither is required, a taxon is usually known by a particular name and ...
. In 2004, Julia Day and
Paul Barrett Paul Franklyn "Legs" Barrett (14 December 1940 – 20 January 2019) was a UK agent and manager of 1950s style rock and roll artists, an author and previously a singer, songwriter and film actor. Barrett was the discoverer, mentor and first man ...
claimed that there were two
morphotype In biology, polymorphism is the occurrence of two or more clearly different morphs or forms, also referred to as alternative ''phenotypes'', in the population of a species. To be classified as such, morphs must occupy the same habitat at the s ...
s present, based on small differences in the thighbones. In 2008 Benson favoured this idea, but in 2010 concluded the differences were illusory. A maxilla fragment, specimen OUM J13506, was, in 1869 assigned, by
Thomas Huxley Thomas Henry Huxley (4 May 1825 – 29 June 1895) was an English biologist and anthropologist who specialized in comparative anatomy. He has become known as "Darwin's Bulldog" for his advocacy of Charles Darwin's theory of evolution. The stor ...
, to ''M. bucklandii''. In 1992 Robert Thomas Bakker claimed it represented a member of the Sinraptoridae; in 2007,
Darren Naish Darren William Naish (born 26 September 1975) is a British vertebrate palaeontologist, author and science communicator. As a researcher, he is best known for his work describing and reevaluating dinosaurs and other Mesozoic reptiles, including ...
thought it was a separate species belonging to the
Abelisauroidea Ceratosaurs are members of the clade Ceratosauria, a group of dinosaurs defined as all theropods sharing a more recent common ancestor with ''Ceratosaurus'' than with birds. The oldest known ceratosaur, ''Saltriovenator'', dates to the earliest ...
. In 2010, Benson pointed out that the fragment was basically indistinguishable from other known ''M. bucklandii'' maxillae, to which it had in fact not been compared by the other authors. Apart from the finds in the
Taynton Limestone Formation The Taynton LimestoneWeishampel, David B; et al. (2004). "Dinosaur distribution (Middle Jurassic, Europe)." In: Weishampel, David B.; Dodson, Peter; and Osmólska, Halszka (eds.): The Dinosauria, 2nd, Berkeley: University of California Press. Pp. ...
, in 1939 Sidney Hugh Reynolds referred remains to ''Megalosaurus'' that had been found in the older Chipping Norton Limestone Formation dating from the early
Bathonian In the geologic timescale the Bathonian is an age (geology), age and stage (stratigraphy), stage of the Middle Jurassic. It lasted from approximately 168.2 ±1.2 annum, Ma to around 165.3 ±1.1 Ma (million years ago). The Bathonian Age succeeds ...
, about 30 single teeth and bones. Though the age disparity makes it problematic to assume an identity with ''Megalosaurus bucklandii'', in 2009 Benson could not establish any relevant anatomical differences with ''M. bucklandii'' among the remains found at one site, the New Park Quarry, and therefore affirmed the reference to that species. However, in another site, the Oakham Quarry, the material contained one bone, an ilium, that was clearly dissimilar. Sometimes
trace fossil A trace fossil, also called an ichnofossil (; ), is a fossil record of biological activity by lifeforms, but not the preserved remains of the organism itself. Trace fossils contrast with body fossils, which are the fossilized remains of part ...
s have been referred to ''Megalosaurus'' or to the
ichnogenus An ichnotaxon (plural ichnotaxa) is "a taxon based on the fossilized work of an organism", i.e. the non-human equivalent of an artifact. ''Ichnotaxon'' comes from the Ancient Greek (''íchnos'') meaning "track" and English , itself derived from ...
''
Megalosauripus ''Megalosauripus'' is an ichnogenus that has been attributed to dinosaurs. The first ever appearance of this ichnospecies is 201 - 197 million years ago during the Early Jurassic period. The last recorded appearance was 156 - 151 million years ag ...
''. In 1997, a famous group of fossilized footprints (ichnites) was found in a limestone quarry at
Ardley Ardley is an English toponym and may refer to: Places * Ardley Cove, South Shetland Islands, Antarctica * Ardley Island, South Shetland Islands, Antarctica * Ardley, Alberta, Canada * Ardley, Oxfordshire, UK ** Ardley Castle Ardley Castle was a ...
, 20 kilometers northeast of
Oxford Oxford () is a City status in the United Kingdom, cathedral city and non-metropolitan district in Oxfordshire, England, of which it is the county town. The city is home to the University of Oxford, the List of oldest universities in continuou ...
. They were thought to have been made by ''Megalosaurus'' and possibly also some left by ''
Cetiosaurus ''Cetiosaurus'' ( meaning 'whale lizard', from the Greek '/ meaning 'sea monster' (later, 'whale') and '/ meaning 'lizard'), is a genus of herbivorous sauropod dinosaur from the Middle Jurassic Period, living about 171 to 165 million years ago ...
''. There are replicas of some of these footprints, set across the lawn of the
Oxford University Museum of Natural History The Oxford University Museum of Natural History (OUMNH) is a museum displaying many of the University of Oxford's natural history specimens, located on Parks Road in Oxford, England. It also contains a lecture theatre which is used by the univers ...
. One track was of a theropod accelerating from walking to running. According to Benson, such referrals are unprovable, as the tracks show no traits unique to ''Megalosaurus''. Certainly they should be limited to finds that are of the same age as ''Megalosaurus bucklandii''. In 2024 five more sets of tracks were discovered at a nearby
Bicester Bicester ( ) is a market town and civil parish in the Cherwell district of Oxfordshire, England, north-west of Oxford. The town is a notable tourist attraction due to the Bicester Village shopping centre. The historical town centre  ...
quarry, with one of them showing clear features of large tridactyl theropod feet distinctive of ''Megalosaurus''. Finds from sites outside England, especially in France, have in the nineteenth and twentieth century been referred to ''M. bucklandii''. In 2010 Benson considered these as either clearly different or too fragmentary to establish an identity.


Description

Since the first finds, many other ''Megalosaurus'' bones have been recovered; however, no complete skeleton has yet been found. Therefore, the details of its physical appearance cannot be certain. However, a full
osteology Osteology () is the scientific study of bones, practiced by osteologists . A subdiscipline of anatomy, anthropology, archaeology and paleontology, osteology is the detailed study of the structure of bones, skeletal elements, teeth, microbone mo ...
of all known material was published in 2010 by Benson.


Size and general build

Traditionally, most texts, following Owen's estimate of 1841, give a body length of 30 feet or nine meters for ''Megalosaurus''. The lack of an articulated dorsal vertebral series makes it difficult to determine an exact size. David Bruce Norman in 1984 thought ''Megalosaurus'' was seven to eight meters long. Gregory S. Paul in 1988 estimated the weight tentatively at 1.1 tons, given a thigh bone 76 centimeters long. The trend in the early twenty-first century to limit the material to the lectotype inspired even lower estimates, disregarding outliers of uncertain identity. Paul in 2010 estimated the size of ''Megalosaurus'' at in length and . However, the same year Benson claimed that ''Megalosaurus'', though medium-sized, was still among the largest of Middle Jurassic theropods. Specimen NHMUK PV OR 31806, a thigh bone 803 millimeters long, would indicate a body weight of 943 kilograms, using the extrapolation method of J.F. Anderson - which method, optimized for mammals, tends to underestimate theropod masses by at least a third. Furthermore, thigh bone specimen OUM J13561 has a length of about 86 centimeters. In general, ''Megalosaurus'' had the typical build of a large theropod. It was bipedal, the horizontal torso being balanced by a long horizontal tail. The hindlimbs were long and strong with three forward-facing weight-bearing toes, the forelimbs relatively short but exceptionally robust and probably carrying three digits. Being a
carnivore A carnivore , or meat-eater (Latin, ''caro'', genitive ''carnis'', meaning meat or "flesh" and ''vorare'' meaning "to devour"), is an animal or plant Plants are the eukaryotes that form the Kingdom (biology), kingdom Plantae; they ar ...
, its large elongated head bore long dagger-like teeth to slice the flesh of its prey. The skeleton of ''Megalosaurus'' is highly ossified, indicating a robust and muscular animal, though the lower leg was not as heavily built as that of ''Torvosaurus'', a close relative.


Skull and lower jaws

The skull of ''Megalosaurus'' is poorly known. The discovered skull elements are generally rather large in relation to the rest of the material. This can either be coincidental or indicate that ''Megalosaurus'' had an uncommonly large head. The
praemaxilla The premaxilla (or praemaxilla) is one of a pair of small cranial bones at the very tip of the upper jaw of many animals, usually, but not always, bearing teeth. In humans, they are fused with the maxilla. The "premaxilla" of therian mammals has ...
is not known, making it impossible to determine whether the snout profile was curved or rectangular. A rather stubby snout is suggested by the fact that the front branch of the
maxilla In vertebrates, the maxilla (: maxillae ) is the upper fixed (not fixed in Neopterygii) bone of the jaw formed from the fusion of two maxillary bones. In humans, the upper jaw includes the hard palate in the front of the mouth. The two maxil ...
was short. In the depression around the
antorbital fenestra An antorbital fenestra (plural: fenestrae) is an opening in the skull that is in front of the eye sockets. This skull character is largely associated with Archosauriformes, archosauriforms, first appearing during the Triassic Period. Among Extant ...
to the front, a smaller non-piercing hollowing can be seen that is probably homologous to the ''fenestra maxillaris''. The maxilla bears 13 teeth. The teeth are relatively large, with a crown length up to seven centimeters. The teeth are supported from behind by tall, triangular, unfused interdental plates. The cutting edges bear 18 to 20 ''denticula'' per centimeter. The tooth formula is probably 4, 13-14/13-14. The
jugal bone The jugal is a skull bone found in most reptiles, amphibians and birds. In mammals, the jugal is often called the malar or zygomatic bone, zygomatic. It is connected to the quadratojugal and maxilla, as well as other bones, which may vary by spe ...
is pneumatized, pierced by a large foramen from the direction of the antorbital fenestra. It was probably hollowed out by an outgrowth of an
air sac Air sacs are spaces within an organism where there is the constant presence of air. Among modern animals, birds possess the most air sacs (9–11), with their extinct dinosaurian relatives showing a great increase in the pneumatization (presence ...
in the
nasal bone The nasal bones are two small oblong bones, varying in size and form in different individuals; they are placed side by side at the middle and upper part of the face and by their junction, form the bridge of the upper one third of the nose. Eac ...
. Such a level of pneumatisation of the jugal is not known from other megalosaurids and might represent a separate
autapomorphy In phylogenetics, an autapomorphy is a distinctive feature, known as a Synapomorphy, derived trait, that is unique to a given taxon. That is, it is found only in one taxon, but not found in any others or Outgroup (cladistics), outgroup taxa, not ...
. The lower jaw is rather robust. It is also straight in top view, without much expansion at the jaw tip, suggesting the lower jaws as a pair, the
mandibula In jawed vertebrates, the mandible (from the Latin ''mandibula'', 'for chewing'), lower jaw, or jawbone is a bone that makes up the lowerand typically more mobilecomponent of the mouth (the upper jaw being known as the maxilla). The jawbone ...
, were narrow. Several traits in 2008 identified as autapomorphies, later transpired to have been the result of damage. However, a unique combination of traits is present in the wide longitudinal groove on the outer side (shared with ''Torvosaurus''), the small third dentary tooth and a vascular channel, below the row of interdental plates, that only is closed from the fifth tooth position onwards. The number of dentary teeth was probably 13 or 14, though the preserved damaged specimens show at most 11 tooth sockets. The interdental plates have smooth inner sides, whereas those of the maxilla are vertically grooved; the same combination is shown by ''
Piatnitzkysaurus ''Piatnitzkysaurus'' ( ; meaning "Piatnitzky's lizard") is a genus of tetanuran theropod dinosaur that lived approximately 179 to 177 million years ago during the lower part of the Jurassic Period in what is now Argentina. ''Piatnitzkysaurus'' wa ...
''. The
surangular The surangular or suprangular is a jaw bone found in most land vertebrates, except mammals. Usually in the back of the jaw, on the upper edge, it is connected to all other jaw bones: dentary, angular bone, angular, splenial and articular. It is o ...
has no bony shelf, or even ridge, on its outer side. There is laterally an oval opening present in front of the jaw joint, a ''foramen surangulare posterior'', but a second ''foramen surangulare anterior'' to the front of it is lacking.


Vertebral column

Although the exact numbers are unknown, the
vertebral column The spinal column, also known as the vertebral column, spine or backbone, is the core part of the axial skeleton in vertebrates. The vertebral column is the defining and eponymous characteristic of the vertebrate. The spinal column is a segmente ...
of ''Megalosaurus'' was probably divided into 10 neck vertebrae, 13 dorsal vertebrae, five sacral vertebrae and 50 to 60 tail vertebrae, as is common for basal
Tetanurae Tetanurae (/ˌtɛtəˈnjuːriː/ or "stiff tails") is a clade that includes most Theropoda, theropod dinosaurs, including Megalosauroidea, megalosauroids, Allosauroidea, allosauroids, and Coelurosauria, coelurosaurs (which includes Tyrannosauroi ...
. The Stonesfield Slate material contains no neck vertebrae; but a single broken anterior cervical vertebra is known from the New Park Quarry, specimen NHMUK PV R9674. The breakage reveals large internal air chambers. The vertebra is also otherwise heavily pneumatized, with large pleurocoels, pneumatic excavations, on its sides. The rear facet of the centrum is strongly concave. The neck ribs are short. The front dorsal vertebrae are slightly opisthocoelous, with convex front centrum facets and concave rear centrum facets. They are also deeply keeled, with the ridge on the underside representing about 50% of the total centrum height. The front dorsals perhaps have a pleurocoel above the diapophysis, the lower rib joint process. The rear dorsal vertebrae, according to Benson, are not pneumatized. They are slightly amphicoelous, with hollow centrum facets. They have secondary joint processes, forming a
hyposphene The hyposphene-hypantrum articulation is an accessory joint found in the vertebrae of several fossil reptiles of the group Archosauromorpha. It consists of a process on the backside of the vertebrae, the hyposphene, that fits in a depression in the ...
hypantrum The hyposphene-hypantrum articulation is an accessory joint found in the vertebrae of several fossil reptiles of the group Archosauromorpha. It consists of a process on the backside of the vertebrae, the hyposphene, that fits in a depression in the ...
complex, the hyposphene having a triangular transverse cross-section. The height of the dorsal spines of the rear dorsals is unknown, but a high spine on a tail vertebra of the New Park Quarry material, specimen NHMUK PV R9677, suggests the presence of a crest on the hip area. The spines of the five vertebrae of the sacrum form a supraneural plate, fused at the top. The undersides of the sacral vertebrae are rounded but the second sacral is keeled; normally it is the third or fourth sacral having a ridge. The sacral vertebrae seem not to be pneumatized but have excavations at their sides. The tail vertebrae are slightly amphicoelous, with hollow centrum facets on both the front and rear side. They have excavations at their sides and a longitudinal groove on the underside. The neural spines of the tail basis are transversely thin and tall, representing more than half of the total vertebral height.


Appendicular skeleton

The shoulderblade or
scapula The scapula (: scapulae or scapulas), also known as the shoulder blade, is the bone that connects the humerus (upper arm bone) with the clavicle (collar bone). Like their connected bones, the scapulae are paired, with each scapula on either side ...
is short and wide, its length about 6.8 times the minimum width; this is a rare and basal trait within Tetanurae. Its top curves slightly to the rear in side view. On the lower outer side of the blade a broad ridge is present, running from just below the shoulder joint to about mid-length where it gradually merges with the blade surface. The middle front edge over about 30% of its length is thinned, forming a slightly protruding crest. The scapula constitutes about half of the shoulder joint, which is orientated obliquely sideways and to below. The
coracoid A coracoid is a paired bone which is part of the shoulder assembly in all vertebrates except therian mammals (marsupials and placentals). In therian mammals (including humans), a coracoid process is present as part of the scapula, but this is n ...
is in all known specimens fused with the scapula into a
scapulocoracoid The scapulocoracoid is the unit of the pectoral girdle that contains the coracoid and scapula. The coracoid itself is a beak-shaped bone that is commonly found in most vertebrates with a few exceptions. The scapula is commonly known as the ''shoulde ...
, lacking a visible suture. The coracoid as such is an oval bone plate, with its longest side attached to the scapula. It is pierced by a large oval
foramen In anatomy and osteology, a foramen (; : foramina, or foramens ; ) is an opening or enclosed gap within the dense connective tissue (bones and deep fasciae) of extant and extinct amniote animals, typically to allow passage of nerves, artery, ...
but the usual boss for the attachment of the upper arm muscles is lacking. The
humerus The humerus (; : humeri) is a long bone in the arm that runs from the shoulder to the elbow. It connects the scapula and the two bones of the lower arm, the radius (bone), radius and ulna, and consists of three sections. The humeral upper extrem ...
is very robust with strongly expanded upper and lower ends. Humerus specimen OUMNH J.13575 has a length of 388 millimeters. Its shaft circumference equals about half of the total humerus length. The humerus head continues to the front and the rear into large bosses, together forming a massive bone plate. On the front outer side of the shaft a large triangular deltopectoral crest is present, the attachment for the '' Musculus pectoralis major'' and the '' Musculus deltoideus''. It covers about the upper half of the shaft length, its apex positioned rather low. The
ulna The ulna or ulnar bone (: ulnae or ulnas) is a long bone in the forearm stretching from the elbow to the wrist. It is on the same side of the forearm as the little finger, running parallel to the Radius (bone), radius, the forearm's other long ...
is extremely robust, for its absolute size more heavily built than with any other known member of the Tetanurae. The only known specimen, NHMUK PV OR 36585, has a length of 232 millimeters and a minimal shaft circumference of 142 millimeters. The ulna is straight in front view and has a large
olecranon The olecranon (, ), is a large, thick, curved bony process on the proximal, posterior end of the ulna. It forms the protruding part of the elbow and is opposite to the cubital fossa or elbow pit (trochlear notch). The olecranon serves as a lever ...
, the attachment process for the '' Musculus triceps brachii''.
Radius In classical geometry, a radius (: radii or radiuses) of a circle or sphere is any of the line segments from its Centre (geometry), center to its perimeter, and in more modern usage, it is also their length. The radius of a regular polygon is th ...
, wrist and hand are unknown. In the pelvis, the ilium is long and low, with a convex upper profile. Its front blade is triangular and rather short; at the front end there is a small drooping point, separated by a notch from the pubic peduncle. The rear blade is roughly rectangular. The outer side of the ilium is concave, serving as an attachment surface for the ''
Musculus iliofemoralis Musculus may refer to: *Andreas Musculus (1514–1581), German Lutheran theologian *Heinrich Musculus (b. 1868), Swedish-Norwegian businessperson *Wolfgang Musculus Wolfgang Musculus (born Müslin or Mauslein; 10 September 1497 – 30 August 1563 ...
'', the main thigh muscle. Above the hip joint, on this surface a low vertical ridge is present with conspicuous vertical grooves. The bottom of the rear blade is excavated by a narrow but deep trough forming a bony shelf for the attachment of the ''
Musculus caudofemoralis brevis Musculus may refer to: *Andreas Musculus Andreas Musculus (Latinized name, Latinized for Andreas Meusel; 29 November 1514 – 29 September 1581) was a German Lutheran theologian and Protestant reformer. Musculus was born in Schneeberg, Saxony, S ...
''. The outer side of the rear blade does not match the inner side, which thus can be seen as a separate "medial blade" that in side view is visible in two places: in the corner between outer side and the ischial peduncle and as a small surface behind the extreme rear tip of the outer side of the rear blade. The pubic bone is straight. The pubic bones of both pelvis halves are connected via narrow bony skirts that originated at a rather high position on the rear side and continued downwards to a point low on the front side of the shaft. The ischium is S-shaped in side view, showing at the transition point between the two curvatures a rough boss on the outer side. On the front edge of the ischial shaft an obturator process is present in the form of a low ridge, at its top separated from the shaft by a notch. To below, this ridge continues into an exceptionally thick bony skirt at the inner rear side of the shaft, covering over half of its length. Towards the end of the shaft, this skirt gradually merges with it. The shaft eventually ends in a sizeable "foot" with a convex lower profile. The thigh bone is straight in front view. Seen from the same direction its head is perpendicular to the shaft, seen from above it is orientated 20° to the front. The
greater trochanter The greater trochanter of the femur is a large, irregular, quadrilateral eminence and a part of the skeletal system. It is directed lateral and medially and slightly posterior. In the adult it is about 2–4 cm lower than the femoral head.Sta ...
is relatively wide and separated from the robust
lesser trochanter In human anatomy, the lesser trochanter is a conical, posteromedial, bony projection from the shaft of the femur. It serves as the principal insertion site of the iliopsoas muscle. Structure The lesser trochanter is a conical posteromedial p ...
in front of it, by a fissure. At the front base of the lesser trochanter a low accessory trochanter is present. At the lower end of the thigh bone a distinct front, extensor, groove separates the
condyle A condyle (;Entry "condyle"
in
s. At the upper inner side of this groove a rough area is present continuing inwards into a longitudinal ridge, a typical megalosauroid trait. The
shinbone The tibia (; : tibiae or tibias), also known as the shinbone or shankbone, is the larger, stronger, and anterior (frontal) of the two bones in the leg below the knee in vertebrates (the other being the fibula, behind and to the outside of the t ...
, or ''tibia'', is relatively straight, slightly curving inwards. To below, its shaft progressively flattens from front to rear, resulting in a generally oval cross-section. For about an eighth of its length the front lower end of the shaft is covered by a vertical branch of the
astragalus Astragalus may refer to: * ''Astragalus'' (plant), a large genus of herbs and small shrubs *Astragalus (bone) The talus (; Latin for ankle or ankle bone; : tali), talus bone, astragalus (), or ankle bone is one of the group of foot bones known ...
. Of the foot, only the second, third and fourth
metatarsals The metatarsal bones or metatarsus (: metatarsi) are a group of five long bones in the midfoot, located between the tarsal bones (which form the heel and the ankle) and the phalanges (toes). Lacking individual names, the metatarsal bones are nu ...
are known, the bone elements that were connected to the three weight-bearing toes. They are straight and robust, showing ligament pits at their lower sides. The third metatarsal has no clear condyles at its lower end, resulting in a more flexible joint, allowing for a modicum of horizontal movement. The top inner side of the third metatarsal carries a unique ridge that fits into a groove along the top outer side of the second metatarsal, causing a tighter connection.


Diagnosis

For decades after its discovery, ''Megalosaurus'' was seen by researchers as the definitive or typical large carnivorous dinosaur. As a result, it began to function as a "wastebasket taxon", and many large or small carnivorous dinosaurs from Europe and elsewhere were assigned to the genus. This slowly changed during the 20th century, when it became common to restrict the genus to fossils found in the middle Jurassic of England. Further restriction occurred in the late 20th and early 21st centuries, researchers such as
Ronan Allain {{Short pages monitor


Sources

*Carrano, M.T.; Benson, R.B.J.; & Sampson, S.D. (2012). "The phylogeny of Tetanurae (Dinosauria: Theropoda)". Journal of Systematic Palaeontology 10(2): 211–300 {{Taxonbar, from=Q131056 Megalosauridae Dinosaur genera Bathonian dinosaurs Fossil taxa described in 1824 Taxa named by William Buckland Dinosaurs of the United Kingdom