Open Paleo

Regnosaurus

Mantell, 1848 REG-noh-SAWR-us Nomen dubium

Named for the Regni, the ancient Roman name for the people of Sussex, England, where the fossils were found, combined with Greek 'sauros' meaning 'lizard'; meaning 'Sussex lizard.'

137.1–132.6 million years ago Valanginian, Early Cretaceous
Early Cretaceous stages

Regnosaurus 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.

Under dispute

Regnosaurus is a nomen dubium whose assignment to Stegosauria is contested. Maidment and colleagues (2008) found no stegosaurian synapomorphies in the single dentary fragment and reassigned it to Thyreophora indeterminate, whereas some reference works (Jones, 2026) still list it as a stegosaur nomen dubium. It is placed at Thyreophora pending diagnostic material.

Species

Regnosaurus northamptoni Mantell, 1848 Nomen dubium

Type species

Named for Spencer Compton, 2nd Marquess of Northampton, who was president of the Royal Society at the time the species was described.

Holotype
BMNH 2422 , Natural History Museum
Material
Portion of a lower jaw
Horizon
Grinstead Clay Formation, Valanginian, Early Cretaceous , 137.1–132.6 million years ago
Locality
Cuckfield, West Sussex, United Kingdom

References

  1. 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. doi:10.1098/rstl.1848.0013

    Names the species on a jaw found by Captain Lambart Brickenden of Warninglid, Sussex, without recording where the specimen was collected.

    mantell1848a
  2. Maidment, S. C. R.; Norman, D. B.; Barrett, P. M.; Upchurch, P. (2008). Systematics and phylogeny of Stegosauria (Dinosauria: Ornithischia). Journal of Systematic Palaeontology 6(4): 367-407. Informa UK Limited. doi:10.1017/S1477201908002459

    Found no stegosaurian synapomorphies in Regnosaurus material, reassigning it to indeterminate Thyreophora.

    maidment2008a
  3. Jones, B. (2026). The Princeton Encyclopedia of Dinosaurs: Ornithischians. Princeton University Press.

    Treats Regnosaurus as a nomen dubium.

    jones2026a
  4. Naish, D.; Martill, D. M. (2008). Dinosaurs of Great Britain and the role of the Geological Society of London in their discovery: Ornithischia. Journal of the Geological Society 165(3): 613-623. Geological Society of London. doi:10.1144/0016-76492007-154

    Places the dentary at Cuckfield and assigns it to the Grinstead Clay, while noting the exact horizon is unknown.

    naish2008a
  5. Galton, P. M. (2009). Notes on Neocomian (Lower Cretaceous) ornithopod dinosaurs from England - Hypsilophodon, Valdosaurus, "Camptosaurus", "Iguanodon" - and referred specimens from Romania and elsewhere. Revue de Paléobiologie, Genève 28(1): 211-273.

    Gives Cuckfield for the same material and corrects the county to West Sussex.

    galton2009a