| Megalosaurus dunkeri Temporal range: Early Cretaceous, | |
|---|---|
Scientific classification  | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Clade: | Dinosauria |
| Clade: | Saurischia |
| Clade: | Theropoda |
| Family: | † Megalosauridae |
| Subfamily: | † Megalosaurinae |
| Genus: | † Megalosaurus |
| Species: | †M. dunkeri |
| Binomial name | |
| †Megalosaurus dunkeri Dames, 1884 | |
| Synonyms | |
| |
"Megalosaurus" dunkeri is a dubious species of theropod dinosaur, known only from a single tooth.
"M." dunkeri was originally named and described by Wilhelm Dames on 16 December 1884 during a lecture. [1] A synopsis of the lecture was actually published in 1885, but because this was in the form of an 1884 yearbook, the latter date is usually given. However, some sources indicate 1887 as the year of publication and designate the species as a "Megalosaurus" dunkeri Dames vide Koken 1887, because in that year, the type specimen, a single tooth, was again described and also illustrated in a publication by Ernst Koken. [2] The specific name honours paleontologist Wilhelm Dunker, who, many years earlier, had discovered the tooth on the Deister, in the main coal seam of Obernkirchen. This holotype had been, under the inventory number UM 84, added by him to the collection of the University of Marburg. [1]
In 1888, Richard Lydekker assigned many fragmentary specimens from the Early Cretaceous of England which had been referred to Megalosaurus in the literature to "Megalosaurus" dunkeri, [3] which thus generally came to be understood as a European Early Cretaceous theropod. (One putative "M." dunkeri specimen from the Wadhurst Clay Formation, however, was later made the holotype of the new species Megalosaurus oweni in 1889. [4] ) In 1923, Friedrich von Huene created the name Altispinax dunkeri for NHMUK R1828, a series of three dorsal vertebrae with very high neural spines. The generic name is derived from Latin "altus" meaning "high" and Neo-Latin "spinax". [5] Oskar Kuhn mistakenly listed "Megalosaurus dunkeri" as the type species of Altispinax in 1939, unaware that von Huene erected Altispinax dunkeri by deliberate use of misidentification. [6]
In a 2016 study Michael W. Maisch considered Altispinax dunkeri to be a valid taxon. The author claimed that von Huene (1923) did not erect the genus Altispinax as a new genus for "Megalosaurus" dunkeri Dames (1884); rather, von Huene erected a new species Altispinax dunkeri by a deliberate use of misidentification in accordance with the article 11.10 of the International Code of Zoological Nomenclature. According to Maisch, the original description of A. dunkeri was in fact not based on the holotype specimen of "Megalosaurus" dunkeri, but on diagnostic material, i.e. three articulated vertebrae from the Wealden of East Sussex - the same specimen which subsequently was made the type specimen of Becklespinax altispinax . Maisch considered Becklespinax to be an objective junior synonym of Altispinax, and Becklespinax altispinax to be an objective junior synonym of Altispinax dunkeri von Huene (1923). [7]
The "Megalosaurus" dunkeri holotype tooth consists of a crown with a length of six centimetres and a base length of twenty-two millimetres. It is moderately recurved with serrations on its back edge running all the way to the base. Dames concluded that there were two traits in which the tooth of "M." dunkeri differed from that of M. bucklandii: the lack of serrations on the front edge and the flatter cross-section. [1] However, already Lydekker pointed out that the serrations could have been worn off, and the greater flatness could have been caused by a compression of the fossil.
A number of teeth from the Weald Clay of southeastern England identified as "M." dunkeri by Lydekker appear to be related to "Megalosaurus" pannoniensis from the early Campanian Grünbach Formation Austria, and similar teeth from the Santonian Csehbánya Formation of Hungary. [8]
Megalosaurus is an extinct genus of large carnivorous theropod dinosaurs of the Middle Jurassic Epoch 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.
The Isle of Wight is one of the richest dinosaur localities in Europe, with over 20 species of dinosaur having been recognised from the early Cretaceous Period, some of which were first identified on the island, as well as the contemporary non-dinosaurian species of crocodile, turtle and pterosaur.
Pelorosaurus is a genus of titanosauriform sauropod dinosaur. Remains referred to Pelorosaurus date from the Early Cretaceous period, about 140-125 million years ago, and have been found in England and Portugal. Thomas Holtz estimated its length at 24 meters.
Proceratosaurus is a genus of carnivorous theropod dinosaur from the Middle Jurassic (Bathonian) of England. It contains a single species. P. bradleyi, known from a mostly complete skull and lower jaws. Proceratosaurus was a small dinosaur, estimated to measure around 3 m (9.8 ft) in length. Its name refers to how it was originally thought to be an ancestor of Ceratosaurus, due to the partially preserved portion of the crest of Proceratosaurus superficially resembling the small crest of Ceratosaurus. Now, however, it is considered a coelurosaur, specifically a member of the family Proceratosauridae, and amongst the earliest known members of the clade Tyrannosauroidea.
Metriacanthosaurus is a genus of metriacanthosaurid dinosaur from the upper Oxford Clay of England, dating to the Late Jurassic period, about 160 million years ago.
Altispinax is a genus of large predatory theropod dinosaur from the Early Cretaceous period of what is now the Wadhurst Clay Formation of East Sussex, England.
Eustreptospondylus is a genus of megalosaurid theropod dinosaur, from the Oxfordian stage of the Late Jurassic period in southern England, at a time when Europe was a series of scattered islands.
Calamospondylus is a genus of theropod dinosaur. It lived during the Early Cretaceous and its fossils were found on the Isle of Wight in southern England. The type species is C. oweni.
Betasuchus is a genus of theropod dinosaur which lived during the Late Cretaceous Period. Betasuchus is, besides Orthomerus, the only dinosaur genus named from remains found in the Netherlands and the only non-avian theropod found in the Maastrichtian Beds.
Walgettosuchus is a dubious or possibly invalid genus of extinct tetanuran theropod dinosaur that lived in Australia during the Late Cretaceous (Cenomanian). It is known from a single caudal vertebra.
Valdoraptor is a genus of theropod dinosaur from the Early Cretaceous. Its fossils were found in England. It is known only from bones of the feet. The holotype, BMNH R2559, was found near Cuckfield in layers of the Tunbridge Wells Sand Formation dating from the late Valanginian. The specimen is damaged lacking parts of the upper and lower ends. It has a conserved length of 215 millimetres (8.5 in) and an estimated length of 240 millimetres (9.4 in). This genus is paleontologically significant for being the first ornithomimosaur specimen known from England and represents the earliest record of ornithomimosaurs.
Sarcolestes is an extinct genus of ankylosaurian ornithischian dinosaur from the Oxford Clay of England. The current type and only species is S. leedsi, and the holotype is a single partial left mandible. The genus and species were named in 1893 by Richard Lydekker, who thought they belonged to a theropod.
Magnosaurus was a genus of theropod dinosaur from the Middle Jurassic of England. It is based on fragmentary remains and has often been confused with or included in Megalosaurus.
Oplosaurus was a genus of sauropod dinosaur from the Barremian-age Lower Cretaceous Wessex Formation of the Isle of Wight, England. It is known from a single tooth usually referred to the contemporaneous "wastebasket taxon" Pelorosaurus, although there is no solid evidence for this.
Ornithopsis is a genus of sauropod dinosaur, from the Early Cretaceous of England. The type species, which is the only species seen as valid today, is O. hulkei, which is only known from fragmentary remains, and has been regarded by many authors as dubious.
Thecocoelurus is a dubious genus of theropod dinosaur from the early Cretaceous period of England. The phylogenetic placement of this genus is uncertain, and it has been referred to an oviraptosaur, an ornithomimosaur, or a therizinosaur by different researchers throughout its history.
Erectopus is an extinct genus of basal allosauroid theropod from the Early Cretaceous La Penthiève Beds Formation of France and also possibly the Cernavodă Formation of southern Romania. The type species is E. superbus, which was initially known as a species of Megalosaurus.
Nuthetes is the name given to a genus of theropod dinosaur, likely a dromaeosaurid, known only from fossil teeth and jaw fragments found in rocks of the middle Berriasian age in the Cherty Freshwater Member of the Lulworth Formation in England and also the Angeac-Charente bonebed in France. If it was a dromaeosaurid, Nuthetes would have been a small predator.
Suchosaurus is a spinosaurid dinosaur from Cretaceous England and Portugal, originally believed to be a genus of crocodile. The type material, consisting of teeth, was used by British palaeontologist Richard Owen to name the species S. cultridens in 1841. Later in 1897, French palaeontologist Henri-Émile Sauvage named a second species, S. girardi, based on two fragments from the mandible and one tooth discovered in Portugal. Suchosaurus is possibly a senior synonym of the contemporary spinosaurid Baryonyx, but is usually considered a dubious name due to the paucity of its remains, and is considered an indeterminate baryonychine. In the Wadhurst Clay Formation of what is now southern England, Suchosaurus lived alongside other dinosaurs, as well as plesiosaurs, mammals, and crocodyliforms.
Duriavenator is a genus of theropod dinosaur that lived in what is now England during the Middle Jurassic, about 168 million years ago. In 1882, upper and lower jaw bones of a dinosaur were collected near Sherborne in Dorset, and Richard Owen considered the fossils to belong to the species Megalosaurus bucklandii, the first named non-bird dinosaur. By 1964, the specimen was recognised as belonging to a different species, and in 1974 it was described as a new species of Megalosaurus, M. hesperis; the specific name means 'the West' or 'western'. Later researchers questioned whether the species belonged to Megalosaurus, in which many fragmentary theropods from around the world had historically been placed. After examining the taxonomic issues surrounding Megalosaurus, Roger B. J. Benson moved M. hesperis to its own genus in 2008, Duriavenator; this name means "Dorset hunter".