[D] Regnosaurus northamptoni (1) [sG] [T]
Mantell, 1848 vide Olshevsky, 1993
Cretaceous Early Valanginian Hauterivian Barremian
Ornithischia Thyreophora Stegosauria Dacentruridae
Wealden Beds, Sussex County, England
Genus - Typespecies
Provisionally valid genus; possible senior subjective synonym of the genus Craterosaurus; once considered a possible senior subjective synonym of Vectisaurus (by Richard Lydekker in 1888) and (incorrectly) a junior subjective synonym of Chondrosteosaurus.
Barrett & Upchurch (1995) classify it as Huayangosauridae, but Olshevsky classify it as Dacentruridae n. fam. Provisionally valid species; type species of the genus Regnosaurus ( by monotype ) ; renamed [Hylaeosaurus northamptoni] by Oskar Kuhn in 1964; possible senior subjective synonym of the species Craterosaurus pottonensis; incorrectly considered a junior subjective synonym of Chondrosteosaurus gigas by George Olshevsky in 1978; holotype specimen origianlly referred to the genus Iguanodon by Gideon Algernon Mantell in 1839 and 1841 and to Hylaeosaurus armatus by Richard Owen in 1840-45 and 1857.
During the 154 years since it was first noted by Gideon Algernon Mantell ( 1839 ) in the scientific literature, the enigmatic type specimen of this species remained misidentified. It started out as a partial lower jaw of a juvenile Iguanodon, then it spent many decades as a nodosaurid (most frequently Hylaeosaurus) fragment, and it was even briefly considered a sauropod.
Only in 1993 was it finally identified as a primitive stegosaur by George Olshevsky, an identification supported through an independent cladistic analysis in 1995 by Britisch paleontologist Paul. M. Barrett and Paul Upchurch. Considering the extreme incompleteness of the specimen, and the fact that good jaw material of primitive stegosaurs was unavailable for comparison prior to the 1982 description of Huayangosaurus by Dong Zhiming, Tang Zilu and Zhoa Shiwu, this long interval of ignorance is not suprprising.
The holotype specimen is a dentary fragment representing roughly the middle thrid of a right mandible.
BMNH R2422, a segment about 7.6 cm ( 3 inches ) long and 4 cm ( 1.6 inches ) wide of a right dentary showing 18 alveoli; the anterior portion of the right splenial also adheres to the medial side of the dentary; the crowns of the teeth are broken off, but 15 tooth alveoli contain roots, and 4 also contain successional teeth; presently kept at the Museum of Natural History, Londen, England.