''Regnosaurus'' (meaning "Sussex lizard") is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

herbivorous A herbivore is an animal anatomically and physiologically adapted to eating plant material, for example foliage or marine algae, for the main component of its diet. As a result of their plant diet, herbivorous animals typically have mouthpar ...

stegosaurian

dinosaur Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the evolution of dinosaurs is t ...

that lived during the Early

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of ...

Period Period may refer to: Common uses * Era, a length or span of time * Full stop (or period), a punctuation mark Arts, entertainment, and media * Period (music), a concept in musical composition * Periodic sentence (or rhetorical period), a concept ...

in what is now

England England is a country that is part of the United Kingdom. It shares land borders with Wales to its west and Scotland to its north. The Irish Sea lies northwest and the Celtic Sea to the southwest. It is separated from continental Europe b ...

. It was one of the first stegosaurs disvovered.

Discovery and species

The fossil remains, a portion of the right lower jaw, were found near Cuckfield in Sussex, and made part of the collection of the

British Museum of Natural History The Natural History Museum in London is a museum that exhibits a vast range of specimens from various segments of natural history. It is one of three major museums on Exhibition Road in South Kensington, the others being the Science Museum ...

. In 1839

Gideon Mantell Gideon Algernon Mantell MRCS FRS (3 February 1790 – 10 November 1852) was a British obstetrician, geologist and palaeontologist. His attempts to reconstruct the structure and life of ''Iguanodon'' began the scientific study of dinosaurs: in ...

reported having noticed the fossil during a visit. Mantell soon came to the conclusion that the specimen represented the, until then unknown, lower jaw of his ''

Iguanodon ''Iguanodon'' ( ; meaning ' iguana-tooth'), named in 1825, is a genus of iguanodontian dinosaur. While many species have been classified in the genus ''Iguanodon'', dating from the late Jurassic Period to the early Cretaceous Period of Asia, ...

'', probably that of a juvenile. On 8 February 1841 he presented it as such to the

Royal Society The Royal Society, formally The Royal Society of London for Improving Natural Knowledge, is a learned society and the United Kingdom's national academy of sciences. The society fulfils a number of roles: promoting science and its benefits, re ...

. This interpretation was immediately challenged by Richard Owen, who felt that any proof of a connection was lacking. In 1848, after several real jaws of ''Iguanodon'' had been discovered, Mantell changed his position, concluding it was a related but different genus or subgenus, coining the name ''Regnosaurus Northamptoni''. The generic name is derived from the

Regni The Regni, Regini, or Regnenses were a Tribe which occupied modern West Sussex, East Sussex, south-west Kent, eastern Surrey, and the eastern edges of Hampshire. Their Tribal centre was at Noviomagus_Reginorum (Chichester in West_Sussex), close ...

, a British tribe inhabiting Sussex. The specific name honours

Spencer Compton, 2nd Marquess of Northampton Spencer Joshua Alwyne Compton, 2nd Marquess of Northampton (2 January 1790 – 17 January 1851), known as Lord Compton from 1796 to 1812 and as Earl Compton from 1812 to 1828, was a British nobleman and patron of science and the arts. Life The ...

, the president of the Royal Society, who was about to resign. By present conventions, the

type species In 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 species that contains the biological type specime ...

is written as ''Regnosaurus northamptoni''. ''Regnosaurus'' is known only from the

holotype A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of sever ...

BMNH 2422, a right mandibular (lower jaw) fragment, consisting of a third of the

dentary In anatomy, the mandible, lower jaw or jawbone is the largest, strongest and lowest bone in the human facial skeleton. It forms the lower jaw and holds the lower teeth in place. The mandible sits beneath the maxilla. It is the only movable bone ...

and a part of the

splenial The splenial is a small bone in the lower jaw of reptiles, amphibians and birds, usually located on the lingual side (closest to the tongue) between the angular and surangular The suprangular or surangular is a jaw bone found in most land ver ...

, found in the Tunbridge Wells Sand Formation. The specimen is six inches long and shows fifteen tooth sockets. Also some replacement teeth are visible. Other bone fragments have sometimes been referred to ''Regnosaurus'', such as a fossil pubis recovered on the

Isle of Wight The Isle of Wight ( ) is a Counties of England, county in the English Channel, off the coast of Hampshire, from which it is separated by the Solent. It is the List of islands of England#Largest islands, largest and List of islands of England#Mo ...

, but as these are of other parts of the body and a reasonably complete skeleton is lacking, the identity cannot be proven. The same is true for some dermal spikes reported by William Blows. ''Regnosaurus'' was probably a rather small animal, about 4 metres (13 feet) long.

Phylogeny

First seen as some iguanodontid, ''Regnosaurus'' was later connected to armoured dinosaurs. In 1888

Richard Lydekker Richard Lydekker (; 25 July 1849 – 16 April 1915) was an English naturalist, geologist and writer of numerous books on natural history. Biography Richard Lydekker was born at Tavistock Square in London. His father was Gerard Wolfe Lydekker, ...

assigned it to the Scelidosauridae. In 1909 Friedrich von Huene classified it in the stegosaurian Omosauridae and in 1911 Alfred von Zittel assigned it to the

Stegosauridae Stegosauridae is a family of thyreophoran dinosaurs (armoured dinosaurs) within the suborder Stegosauria. The clade is defined as all species of dinosaurs more closely related to ''Stegosaurus'' than '' Huayangosaurus''.David B. Weishampel, Pete ...

but these groups then had a different content and also included armoured forms. In 1956

Alfred Romer Alfred Sherwood Romer (December 28, 1894 – November 5, 1973) was an American paleontologist and biologist and a specialist in vertebrate evolution. Biography Alfred Romer was born in White Plains, New York, the son of Harry Houston Romer an ...

synonymised it with ''

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 ...

''. An entirely different suggestion was made by

John Ostrom John Harold Ostrom (February 18, 1928 – July 16, 2005) was an American paleontologist who revolutionized modern understanding of dinosaurs in the 1960s. As first proposed by Thomas Henry Huxley in the 1860s, Ostrom showed that dinosaurs were ...

who surmised it might have been a sauropod. The first to state that it was a stegosaurian in the modern sense was George Olshevsky in 1993. This was confirmed by Paul Barrett and Paul Upchurch in 1995 who concluded that it is a stegosaur similar to '' Huayangosaurus'', as the jaws are very similar. As the remains are so limited, many recent researchers have concluded ''Regnosaurus'' to be a '' nomen dubium''.

References

{{Taxonbar, from=Q140766 Stegosaurs Barremian life Hauterivian life Valanginian life Early Cretaceous dinosaurs of Europe Cretaceous England Fossils of England Fossil taxa described in 1848 Taxa named by Gideon Mantell Nomina dubia Ornithischian genera

Discovery and species

Phylogeny

See also

References