Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. Regnosaurus (meaning "Sussex lizard") is a genus of dinosaur that lived during the Early Cretaceous in what is now England.The fossil remains, a portion of the right lower jaw, were found near Cuckfield in Sussex, and made part of the collection of the . 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.