Regnosaurus

Regnosaurus (meaning "Sussex lizard") is an extinct genus of herbivorous presumably armored dinosaur known from the early Cretaceous Wealden Formation of England. The genus contains a single species, Regnosaurus northamptoni, known from a single partial jaw bone. Regnosaurus has traditionally been regarded as a stegosaur, possibly related to the Jurassic Huayangosaurus of China. Later research considers it to be a dubious, indeterminate thyreophoran.

==Discovery and species== thumb|left|upright|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 concluded 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. 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, 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. By present conventions, the type species is written as Regnosaurus northamptoni.