Regnosaurus

Regnosaurus
Temporal range: Early Cretaceous
Holotype jaw fragment
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Sauropsida
Superorder: Dinosauria
Order: Ornithischia
Suborder: Thyreophora
Infraorder: Stegosauria
Family: Huayangosauridae
Genus: Regnosaurus
Mantell, 1848
Species
  • R. northamptoni Mantell, 1848 (type)

Regnosaurus (meaning "Sussex lizard") is a genus of herbivorous stegosaurian dinosaur that lived during the Early Cretaceous Period in what is now England.

Discovery and species

Jaw of Regnosaurus compared to that of an iguana

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. In 1839 Gideon Mantell 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, probably that of a juvenile. On 8 February 1841 he presented it as such to the Royal Society.[1] 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.[2] The generic name is derived from the Regni or Regnenses, a British tribe inhabiting Sussex. The specific name honours Spencer Compton, 2nd Marquess of Northampton, the president of the Royal Society, who was about to resign.[3] By present conventions, the type species is written as Regnosaurus northamptoni.

Regnosaurus is known only from the holotype BMNH 2422, a right mandibular (lower jaw) fragment, consisting of a third of the dentary and a part of the splenial. 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, 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.[4] 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 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 but these groups then had a different content and also included armoured forms. In 1956 Alfred Romer synonymised it with Hylaeosaurus. An entirely different suggestion was made by John Ostrom 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.[5] This was confirmed by Paul Barret and Paul Upchurch in 1995[6] 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.

See also

References

  1. ↑ Mantell, G.A., 1841, "Memoir on a portion of the lower jaw of the Iguanodon, and on the remains of the Hylæosaurus and other Saurians, discovered in the Strata of Tilgate Forest, in Sussex", Philosophical Transactions of the Royal Society of London, 131(2): 131-151
  2. ↑ Deborah Cadbury (2000). The Dinosaur Hunters. Fourth Estate, London. ISBN 1-85702-959-3.
  3. ↑ Mantell, G.A., 1848, "On the structure of the jaws and teeth of the Iguanodon", Philosophical Transactions of the Royal Society of London 138: 183-202
  4. ↑ Blows W.T. (2001). "Possible Stegosaur Dermal Armor from the Lower Cretaceous of Southern England". In Carpenter, Kenneth(ed). The Armored Dinosaurs. Indiana University Press. pp. 130–140. ISBN 0-253-33964-2.
  5. ↑ Olshevsky, G., and Ford, T.L., 1993, "The origin and evolution of the stegosaurs", Gakken Mook, Dinosaur Frontline, 4: 65-103
  6. ↑ Barret PM & Upchurch P (1995). "Regnosaurus northamptoni, a stegosaurian dinosaur from the Lower Cretaceous of Southern England". Geological Magazine. 132 (2): 213–222. doi:10.1017/S0016756800011754.
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