Megalosaurus

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Megalosaurus
Temporal range:
Ma
↓
lectotype dentary, identified by Buckland
in 1824
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Clade: Saurischia
Clade: Theropoda
Family: †Megalosauridae
Subfamily: †
Megalosaurinae
Genus: †Megalosaurus
Buckland, 1824
Species:
†M. bucklandii
Binomial name
†Megalosaurus bucklandii
Mantell, 1827
Synonyms
  • Megalosaurus bucklandi Meyer, 1832
  • Megalosaurus conybeari Ritgen, 1826 (nomen oblitum)
  • Scrotum Humanum Brookes, 1763 (nomen oblitum)

Megalosaurus (meaning "great lizard", from

theropod dinosaurs of the Middle Jurassic Epoch (Bathonian stage, 166 million years ago) of southern England. Although fossils from other areas have been assigned to the genus, the only certain remains of Megalosaurus come from Oxfordshire and date to the late Middle Jurassic
.

Megalosaurus was, in 1824, the first genus of non-avian dinosaur to be validly named. The

Dinosauria. On Owen's directions a model was made as one of the Crystal Palace Dinosaurs
, 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 20 metres (66 ft) in length. In 1842, Owen concluded that it was no longer than 9 metres (30 ft). 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. Megalosaurus was about 6 metres (20 ft) long, weighing about 700 kilograms (1,500 lb). 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.

Discovery and naming

Edward Lhuyd's tooth (specimen OU 1328)

Possible Megalosaurus tooth OU 1328

In 1699,

theropod, in 1699.[2][3] Later studies found that the theropod tooth, known as specimen 1328 (University of Oxford coll. #1328; lost?) almost certainly was a tooth crown that belonged to an unknown species of Megalosaurus.[4] OU 1328 has since been lost and it was not confidently assigned to Megalosaurus until the tooth was re-described by Delair & Sarjeant (2002).[4]

OU 1328 was collected near Caswell, near Witney, Oxfordshire sometime during the 17th century and became the third dinosaur fossil to ever be illustrated,[5] after "Scrotum humanum" in 1677 and "Rutellum impicatum" in 1699.

"Scrotum humanum"

The cover of Robert Plot's Natural History of Oxfordshire, 1677 (right). Plot's illustration of the lower extremity of the femur dubbed "Scrotum humanum" (left)

Megalosaurus may have been the first non

thighbone or femur of a large animal and he recognised 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.[8] The bone has since been lost, but the illustration is detailed enough that some have since identified it as that of Megalosaurus.[9]

It has also been argued that this possible Megalosaurus bone was given the very first

type specimen of a new biological genus. According to the rules of the International Code of Zoological Nomenclature (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, an invalid "forgotten name".[12]

In 1993, after the death of Halstead, his friend William A.S. Sarjeant submitted a petition to the International Commission on Zoological Nomenclature 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 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.[13]

Buckland's research

Lithography from William Buckland's "Notice on the Megalosaurus or great Fossil Lizard of Stonesfield", 1824. Caption reads "anterior extremity of the right lower jaw of the Megalosaurus from Stonesfield near Oxford".

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 Robert Gunther in 1925, among them was a partial lower jaw of Megalosaurus. It was discovered about 40 feet (12 m) underground in a Stonesfield Slate mine during the early 1790s and was acquired in October 1797 by Christopher Pegge for 10s.6d. and added to the collection of the Anatomy School of Christ Church, Oxford.[14]

In the early nineteenth century, more discoveries were made. In 1815,

lithographies. Finally, on 20 February 1824, during the same meeting of the Geological Society of London in which Conybeare described a very complete specimen of Plesiosaurus, 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.[9][18] Megalosaurus was the first non-avian dinosaur genus named; the first of which the remains had with certainty been scientifically described was Streptospondylus, in 1808 by Cuvier.[19]

Referred tail vertebra, BMNH 9672. The top of its neural spine has broken off, which would have been about twice as long

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

lectotype.[20] 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 and mistaking the ischium for a clavicle. Buckland identified the organism as being a giant animal belonging to the Sauria – 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 metres long in life.[18]

Etymology

Buckland had not provided a specific name, as was not uncommon in the early nineteenth century, when the genus was still seen as the more essential concept.[1] In 1826, Ferdinand von Ritgen gave this dinosaur a complete binomial, Megalosaurus conybeari,[21] which however was not much used by later authors and is now considered a nomen oblitum. A year later, in 1827, Gideon Mantell included Megalosaurus in his geological survey of southeastern England, and assigned the species its current valid binomial name, Megalosaurus bucklandii.[22] Until recently, the form Megalosaurus bucklandi was often used, a variant first published in 1832 by Christian Erich Hermann von Meyer[23] – and sometimes erroneously ascribed to von Ritgen – but the more original M. bucklandii has priority.

Early reconstructions

bipedal
, like most theropods

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

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 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".[24]

Édouard Riou's 1863 depiction of Iguanodon battling Megalosaurus

Around 1840, it became fashionable in England to espouse the concept of the

British Association for the Advancement of Science 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, Hylaeosaurus 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.[25]

Von Meyer's restoration of Megalosaurus from before 1897; showing it bipedal with long neural spines

In 1852,

Becklespinax, but Owen referred them to Megalosaurus.[26][27] The models at the exhibition created a general public awareness for the first time, at least in England, that ancient reptiles had existed.[28]

The presumption that carnivorous dinosaurs, like Megalosaurus, were quadrupeds was first challenged by the find of Compsognathus 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 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.[26] During the 1870s, North American discoveries of large theropods, like Allosaurus, confirmed that they were bipedal. The Oxford University Museum of Natural History display contains most of the specimens from the original description by Buckland.[29]

Later finds of Megalosaurus bucklandii

Replica of theropod footprints attributed to Megalosaurus

The quarries at

Sinraptoridae;[34] in 2007, Darren Naish thought it was a separate species belonging to the Abelisauroidea.[26] 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.[30]

Referred femur in France

Apart from the finds in the

Chipping Norton Limestone Formation dating from the early Bathonian, about 30 single teeth and bones.[35][36] 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.[15]

Sometimes

ichnites) was found in a limestone quarry at Ardley, 20 kilometres northeast of Oxford. They were thought to have been made by Megalosaurus and possibly also some left by Cetiosaurus. There are replicas of some of these footprints, set across the lawn of the Oxford University Museum of Natural History. One track was of a theropod accelerating from walking to running.[37] 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.[30]

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.[30]

Description

lectotype
in pink, largest specimen in red)

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 of all known material was published in 2010 by Benson.[30]

Size and general build

paralectotype
material in white, and elements from other specimens in blue

Traditionally, most texts, following Owen's estimate of 1841, give a body length of 30 feet or nine metres for Megalosaurus.[38] 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 metres long.[39] Gregory S. Paul in 1988 estimated the weight tentatively at 1.1 tonnes, given a thigh bone 76 centimetres long.[40] 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 6 metres (20 ft) in length and 700 kilograms (1,500 lb).[41] However, the same year Benson claimed that Megalosaurus, though medium-sized, was still among the largest of Middle Jurassic theropods. Specimen BMNH 31806, a thigh bone 803 millimetres long, would indicate a body weight of 943 kilogrammes, using the extrapolation method of J.F. Anderson — which method, optimised for mammals, tends to underestimate theropod masses by at least a third. Furthermore, thigh bone specimen OUM J13561 has a length of about 86 centimetres.[30]

Hip, femur and sacrum

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, its large elongated head bore long dagger-like teeth to slice the flesh of its prey.[38] 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.[30]

Skull and lower jaws

Referred tooth of M. bucklandii

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

air sac in the nasal bone. Such a level of pneumatisation of the jugal is not known from other megalosaurids and might represent a separate autapomorphy.[30]

Cast of the lower jaw

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, 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. The surangular 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.[30]

Vertebral column

OUM J13576, an articulated sacrum

Although the exact numbers are unknown, the vertebral column 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.[42]

The Stonesfield Slate material contains no neck vertebrae; but a single broken anterior cervical vertebra is known from the New Park Quarry, specimen BMNH R9674. The breakage reveals large internal air chambers. The vertebra is also otherwise heavily pneumatised, with large

hypantrum 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 BMNH 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 pneumatised 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.[30]

Appendicular skeleton

Lithograph of the femur, from a posterior (left) and medial view (right). Work by James Erxleben in the 1800s

The

shoulderblade or scapula 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 is in all known specimens fused with the scapula into a scapulocoracoid, 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 but the usual boss for the attachment of the upper arm muscles is lacking.[30]

The

Musculus triceps brachii. Radius, wrist and hand are unknown.[30]

Lithograph of the Ilium. Work from the 1800s drawn by James Erxleben

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, 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. 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.[30]

Tibia and metatarsals

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

metatarsals 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.[30]

Diagnosis

Restoration of Megalosaurus, with a mostly hypothetical head

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

autapomorphies, or unique distinguishing characteristics, in the lower jaw that could be used to separate Megalosaurus from other megalosaurids.[32]

Various distinguishing traits of the lower jaw have been established. The longitudinal groove on the outer surface of the dentary is wide. The third tooth socket of the dentary is not enlarged. Seen from above, the dentary is straight without an expanded jaw tip. The interdental plates, reinforcing the teeth from behind, of the lower jaw are tall. Benson also concluded it would be most

parsimonious to assume that the Stonesfield Slate material represents a single species. If so, several additional distinctive traits can be observed in other parts of the skeleton. The low vertical ridge on the outer side of the ilium, above the hip joint, shows parallel vertical grooves. The bony skirts between the shafts of the ischia are thick and touch each other forming an almost flat surface. There is a boss present on the lower outer side of the ischium shaft with a rough surface. The underside of the second sacral vertebra has an angular longitudinal keel. A ridge on the upper side of the third metatarsal connected to a groove in the side of the second metatarsal. The middle of the front edge of the scapula forms a thin crest.[43]

Phylogeny

Referred tibia, lateral view (left), posterior view (right). Lithograph drawn by James Erxleben in the 19th century

In 1824, Buckland assigned Megalosaurus to the Sauria, assuming within the Sauria a close affinity with modern lizards, more than with crocodiles.

Dinosauria.[25] In 1850, Prince Charles Lucien Bonaparte coined a separate family Megalosauridae with Megalosaurus as the type genus.[44] For a long time, the precise relationships of Megalosaurus remained vague. It was seen as a "primitive" member of the Carnosauria, the group in which most large theropods were united.[45]

In the late 20th century the new method of

Megalosaurinae,[46] giving this cladogram:[47]

Megalosauroidea

Paleobiology

Ribs and pelvic elements. The left rib fragment shows a healed fracture at the underside of the base of the capitulum. Work from the 1800s drawn by James Erxleben

Living in what is now Europe, during the Jurassic Period (~201 to ~145 million years ago), Megalosaurus may have hunted

sauropods.[38] Repeated descriptions during the nineteenth and early twentieth century of Megalosaurus hunting Iguanodon (another of the earliest dinosaurs named) through the forests that then covered the continent are now known to be inaccurate, because Iguanodon skeletons are found in much younger Early Cretaceous formations. The only specimens belonging to Megalosaurus bucklandii are from the Lower/Middle Bathonian of Oxfordshire and Gloucestershire.[42] No material from outside the Bathonian formations of England can be referred to Megalosaurus.[48] It lived alongside the theropods Cruxicheiros,[48] Iliosuchus and Streptospondylus,[42] and the sauropods Cardiodon,[42] Cetiosaurus,[41] and possibly Cetiosauriscus.[42] The pterosaur Rhamphocephalus, and indeterminate sauropod and ornithopod remains have also been found alongside fossils of Megalosaurus.[42]

Benson in 2010 concluded from its size and common distribution that Megalosaurus was the

London-Brabant Massif.[30]

Paleopathology

A Megalosaurus rib figured in 1856 and 1884 by

Sir Richard Owen has a pathological swollen spot near the base of its capitular process. The swollen spot appears to have been caused by a healed fracture and is located at the point where it would have articulated with its vertebra.[49]

Species and synonyms

During the later nineteenth century, Megalosaurus was seen as the typical carnivorous dinosaur. If remains were found that were not deemed sufficiently distinct to warrant a separate genus, often single teeth, these were classified under Megalosaurus, which thus began to function as a wastebasket taxon, a sort of default genus.[38] Eventually, Megalosaurus contained more species than any other non-avian dinosaur genus,[17] most of them of dubious validity. During the twentieth century, this practice was gradually discontinued; but scientists discovering theropods that had been mistakenly classified under a different animal group in older literature, still felt themselves forced to rename them, again choosing Megalosaurus as the default generic name.[15]

Species named in the 19th century

Dentary with replacement teeth, found in 1851 and in 1857 by Owen referred to Megalosaurus, but now lost. 1800s illustration by James Erxleben
Type dentary and referred teeth. 1800s restoration by James Erxleben

In 1857,

Harry Govier Seeley named two possible theropod teeth found in Austria Megalosaurus pannoniensis.[60] The specific name refers to Pannonia. It is a nomen dubium, possibly an indeterminate member of the Dromaeosauridae or Tyrannosauroidea.[58] In 1883, Seeley named Megalosaurus bredai, based on a thigh bone, specimen BMNH 42997 found near Maastricht, the Netherlands. The specific name honours Jacob Gijsbertus Samuël van Breda.[61] In 1932, this was made a separate genus Betasuchus by Friedrich von Huene.[62]

In 1882,

Laelaps, used by Cope to denote a theropod, had been preoccupied by a mite. Marsh had therefore provided the replacement name Dryptosaurus, but Henry Fairfield Osborn, a partisan of Cope, rejected this replacement and thus in 1898 renamed Laelaps aquilunguis Cope 1866 into Megalosaurus aquilunguis.[72]

Species named in the 20th century

Claw of Megalosaurus lonzeensis

In 1901 Baron

Franz Nopcsa renamed Laelaps trihedrodon Cope 1877 into Megalosaurus trihedrodon.[73] In the same publication Nopcsa renamed Poekilopleuron valens Leidy 1870 into Megalosaurus valens; this probably represents fossil material of Allosaurus.[74] In 1902, Nopcsa named Megalosaurus hungaricus based on two teeth found in Transylvania,[75] then part of the Kingdom of Hungary. The specimens, MAFI ob. 3106, were later lost. It represents an indeterminate theropod.[52] In 1903, Louis Dollo named Megalosaurus lonzeensis based on a manual claw found near Lonzee in Belgium.[76] He had first reported this claw in 1883,[77] and as a result some sources by mistake indicate this year as the date of the naming. It perhaps represents a member of the Noasauridae, or an indeterminate member of the Coelurosauria.[55] In 1907/1908, von Huene renamed Streptospondylus cuvieri Owen 1842, based on a presently lost partial vertebra, into Megalosaurus cuvieri.[78] This is today seen as a nomen dubium, an indeterminate member of the Tetanurae.[79] In 1909, Richard Lydekker named Megalosaurus woodwardi, based on a maxilla with tooth, specimen BMNH 41352.[80] This is today seen as a nomen dubium, an indeterminate member of the Theropoda.[55]

In 1910,

Pombal in the Jurassic of Portugal.[95] Today it is seen as a nomen dubium, an indeterminate member of the Theropoda.[58]

In 1965, Oskar Kuhn renamed Zanclodon silesiacus Jaekel 1910 into Megalosaurus? silesiacus.[96] It is a nomen dubium based on the tooth of some indeterminate predatory Triassic archosaur, found in Silesia, perhaps a theropod.[58] In 1966, Guillermo del Corro named Megalosaurus inexpectatus, named "the unexpected" as it was discovered on a sauropod site with remains of Chubutisaurus, based on specimen MACN 18.172, a tooth found in Argentina.[97] It might represent a member of the Carcharodontosauridae.[55] In 1970, Rodney Steel named two Megalosaurus species.[98] Firstly, he renamed Iliosuchus incognitus Huene 1932 into Megalosaurus incognitus. Secondly, he renamed Nuthetes destructor Owen 1854 into Megalosaurus destructor. Both genera are today seen as not identical to Megalosaurus.[74] Michael Waldman in 1974 renamed Sarcosaurus andrewsi Huene 1932 into Megalosaurus andrewsi.[99] Indeed, Sarcosaurus andrewsi is today by some scientists not seen as directly related to the type species of Sarcosaurus: Sarcosaurus woodi.[26] In the same publication Waldman named Megalosaurus hesperis, "the western one", based on skull fragments from the Middle Jurassic. In 2008 this was made the separate genus Duriavenator.[100] Del Corro in 1974 named Megalosaurus chubutensis, based on specimen MACN 18.189, a tooth found in Chubut Province.[101] It is a nomen dubium, a possible carcharodontosaurid,[102] or a very large abelisaurid.[52]

Dentary of ?Megalosaurus cambrensis. Lithograph by Newton in 1899

In 1985,

Peter Malcolm Galton renamed Zanclodon cambrensis Newton 1899, based on a left lower jaw, specimen BGS 6532 found at Bridgend, into ?Megalosaurus cambrensis because it was not a basal sauropodomorph.[108] It is a senior synonym of Gressylosaurus cambrensis Olshevsky 1991.[68] The specific name refers to Cambria, the Latin name of Wales. It probably represents a member of the Coelophysoidea,[109] or some other predatory archosaur.[52]

Species list

The complex naming history can be summarised in a formal species list. The naming authors are directly mentioned behind the name. If the name has been changed, they are placed in parentheses and the authors of the changed name are mentioned behind them. The list also indicates whether a name has been insufficiently described (nomen nudum), is not taxonomically identifiable at the generic level (nomen dubium), or fallen out of use (nomen oblitum). Reclassifications under a different genus are mentioned behind the "=" sign; if the reclassification is today considered valid, it is listed under Reassigned species.

Valid species
Nomina dubia and species that were formerly referred to Megalosaurus but not nominal species of that genus
  • Megalosaurus horridus (
    Owen, 1842) Huene, 1907, = Streptospondylus cuvieri Owen, 1842
  • Megalosaurus woodwardi Lydekker, 1909 (nomen dubium), senior objective synonym of Megalosaurus lydekkeri Huene, 1926, non Megalosaurus (Magnosaurus) woodwardi (Huene, 1932) Huene, 1932
  • Megalosaurus ingens Janensch, 1920, = Ceratosaurus ingens (Janensch, 1920) Paul, 1988
  • Megalosaurus poikilopleuron Huene, 1923, junior synonym of Poekilopleuron bucklandii Eudes-Deslongchampus, 1838
  • Megalosaurus lydekkeri, Huene, 1926 (nomen dubium) = Megalosaurus woodwardi Lydekker, 1909; = Magnosaurus lydekkeri (Huene, 1926) Huene, 1932
  • Megalosaurus terquemi Huene, 1926 (nomen dubium), = Gresslyosaurus terquemi (Huene, 1926) Lapparent, 1967
  • Megalosaurus (Magnosaurus) woodwardi (Huene, 1932) Huene, 1932, = Magnosaurus woodwardi Huene, 1932, objective synonym of Sarcosaurus andrewsi Huene, 1932, = Megalosaurus andrewsi (Huene, 1932) Waldman, 1974, non Megalosaurus woodwardi Lydekker, 1909
  • Megalosaurus mersensis Lapparent, 1955
  • Megalosaurus nicaeensis (Ambayrac, 1913) Romer, 1956, = Aggiosaurus nicaeensis Ambayrac, 1913
  • Megalosaurus africanus Huene, 1956, junior objective synonym of Carcharodontosaurus saharicus (Depéret & Savornin, 1925) Stromer, 1931
  • Megalosaurus pombali Lapparent & Zbyszewski, 1957
  • Megalosaurus silesiacus (Jaekel, 1910) Kuhn, 1965(nomen dubium), = Zanclodon silesiacus Jaekel, 1910
  • Megalosaurus inexpectatus Corro, 1966 (nomen dubium)
  • Megalosaurus destructor (Owen, 1854) Steel, 1970, = Nuthetes destructor Owen, 1854
  • Megalosaurus incognitus (Huene, 1932) Steel, 1970, junior synonym of Iliosuchus incognitus Huene, 1932
  • Megalosaurus andrewsi (Huene, 1932) Waldman, 1974, = Sarcosaurus andrewsi Huene, 1932, an objective synonym of Magnosaurus woodwardi Huene, 1932
  • Megalosaurus chubutensis Corro, 1974 (nomen dubium)
  • Megalosaurus rawesi (Lydekker, 1890) Vianey-Liaud, Jain & Sahni, 1987, = Massospondylus rawesi Lydekker, 1890
  • Megalosaurus tanneri (Galton & Jensen, 1979) Paul, 1988, junior synonym of Torvosaurus tanneri Galton & Jensen, 1979
  • Megalosaurus schmidti (Kiprijanow, 1883) Olshevsky, 1991, a chimera, = Poekilopleuron schmidti Kiprijanow, 1883
  • Megalosaurus ornatus (Huene, 1905) Probst & Windolf, 1993 (nomen vanum), = Plateosaurus ornatus Huene, 1905
  • Megalosaurus monasterii (Münster, 1846) per Windolf 1997, = Saurocephalus monasterii Münster, 1846
  • ?Megalosaurus cambrensis (Newton, 1899) Galton, 1998, = Zanclodon cambrensis Newton, 1899 = Gressylosaurus cambrensis (Newton, 1899) Olshevsky, 1991
  • Megalosaurus dunkeri, Dames, 1884, = Streptospondylus dunkeri, (Dames, 1884) Depéret & Savornin, 1928, = Prodeinodon
dunkeri, (Dames, 1884) Ruiz-Omeñaca & Canudo, 2003
Nomina nuda
  • Megalosaurus tibetensis Zhao, 1986
  • Megalosaurus dapukaensis Zhao, 1986
Reassigned species
  • Megalosaurus superbus, Sauvage, 1882 = Erectopus superbus (Sauvage, 1882) Huene, 1923
  • Megalosaurus bredai, Seeley, 1883, = Betasuchus bredai (Seeley, 1883) Huene, 1932
  • Megalosaurus oweni, Lydekker, 1889, = Altispinax oweni (Lydekker, 1889) Huene, 1923, = Valdoraptor oweni (Lydekker, 1889) Olshevsky, 1991
  • Megalosaurus crenatissimus, Depéret, 1896, = Dryptosaurus crenatissimus (Depéret, 1896) Depéret, 1928, = Majungasaurus crenatissimus (Depéret, 1896) Lavocat, 1955, senior synonym of Majungatholus atopus Sues & Taquet 1979
  • Megalosaurus bradleyi, Woodward, 1910, = Proceratosaurus bradleyi (Woodward, 1910) Huene, 1926
  • Megalosaurus parkeri, Huene, 1923, = Altispinax parkeri (Huene, 1923) Huene, 1932, = Metriacanthosaurus parkeri (Huene, 1923) Walker, 1946
  • Megalosaurus nethercombensis, Huene, 1923, = Magnosaurus nethercombensis (Huene, 1923) Huene, 1932
  • Megalosaurus saharicus, Depéret & Savornin, 1925, = Megalosaurus (Dryptosaurus) saharicus (Depéret & Savornin, 1925) Depéret & Savornin, 1927; = Carcharodontosaurus saharicus (Depéret & Savornin, 1925) Stromer, 1931, = Megalosaurus africanus (typo)Huene, 1956
  • Megalosaurus wetherilli, Welles, 1954, = Dilophosaurus wetherilli (Welles, 1954) Welles, 1970
  • Megalosaurus hesperis, Waldman, 1974, = Duriavenator hesperis (Waldman, 1974) Benson, 2008

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