Open Paleo

Cumnoria

Seeley, 1888 kum-NOH-ree-uh

Named for Cumnor, a village in Oxfordshire, England, near where the fossils were found.

154.8–149.2 million years ago Kimmeridgian, Late Jurassic
Late Jurassic stages

Cumnoria is a genus of basal iguanodontian dinosaur that lived during the Late Jurassic period (Kimmeridgian age) in what is now Oxfordshire, United Kingdom.

Under dispute

The position of Cumnoria prestwichii is unresolved across three incompatible hypotheses. It has been recovered as a basal styracosternan (McDonald, 2011), within a camptosaurid grouping alongside Camptosaurus dispar (Sánchez-Fenollosa and colleagues, 2023; Fonseca and colleagues, 2024; Dieudonné and colleagues, 2026), and outside Ankylopollexia altogether (Maidment and colleagues, 2023; Rotatori and colleagues, 2026). Because Camptosauridae and Styracosterna are complementary stem clades defined on Camptosaurus dispar and Iguanodon bernissartensis, the second and third hypotheses both exclude it from Styracosterna. Some analyses cannot place it at all and prune it as an unstable wildcard (Poole, 2022). It is placed at Dryomorpha incertae sedis, the least inclusive clade common to every hypothesis. Its separation from the North American Camptosaurus is also contested. Carpenter and Lamanna (2015) regarded Cumnoria as a junior subjective synonym of Camptosaurus, holding that its sole recognized autapomorphy, a small intramaxillary fossa, warranted distinction at the specific rather than the generic level, and Sánchez-Fenollosa and colleagues (2023) followed them. The redescription by Maidment and colleagues (2023) instead diagnosed Cumnoria on two autapomorphies of the pectoral girdle and recovered it outside Ankylopollexia, and subsequent work has continued to treat it as a distinct genus (Rotatori and colleagues, 2026). It is retained as a valid genus.

Diagnosis

  1. Teeth with different type of parallel ridging and coarser serration than Iguanodon
  2. Vertebrae relatively wider with neural arch and centrum both more depressed
  3. Laminae of the neural arch very stout and neural canal very small
  4. Sacral vertebrae not anchylosed, only four in number, and convex on the ventral surface
  5. Early caudal vertebrae reduced in length with small neural arch
  6. Astragalus and calcaneum separate

Species

Cumnoria prestwichii Seeley, 1888

Type species

Named for Professor Joseph Prestwich, the geologist who first reported the fossils in 1879.

Holotype
OUMNH PAL-J.003303 , Oxford University Museum of Natural History
Material
Almost complete skeleton
Horizon
lower Kimmeridge Clay Formation, Kimmeridgian, Late Jurassic , 154.8–149.2 million years ago
Locality
Chawley Brick Pit, Hurst Hill, Cumnor, Oxfordshire, United Kingdom

References

  1. Seeley, H. G. (1888). On Cumnoria, an iguanodont genus founded upon the Iguanodon prestwichi, Hulke. Report of the British Association for the Advancement of Science 57: 698.

    Erects the genus Cumnoria for Iguanodon prestwichii Hulke.

    seeley1888a
  2. Lydekker, R. (1889). On the remains and affinities of five genera of Mesozoic reptiles. Quarterly Journal of the Geological Society of London 45(1-4): 41-59. Geological Society of London. doi:10.1144/GSL.JGS.1889.045.01-04.04

    Reassigns the species to Camptosaurus (Camptosaurus prestwichii).

    lydekker1889b
  3. Galton, P. M.; Powell, H. P. (1980). The ornithischian dinosaur Camptosaurus prestwichii from the Upper Jurassic of England. Palaeontology 23: 411-443.

    First modern description of the material, as Camptosaurus prestwichii.

    galton1980c
  4. Norman, D. B. (1998). On Asian ornithopods (Dinosauria: Ornithischia). 3. A new species of iguanodontid dinosaur. Zoological Journal of the Linnean Society 122(1-2): 291-348. Oxford University Press (OUP). doi:10.1111/j.1096-3642.1998.tb02533.x

    Revives the genus Cumnoria.

    norman1998a
  5. 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

    Revives the genus Cumnoria.

    naish2008a
  6. Jones, B. (2026). The Princeton Encyclopedia of Dinosaurs: Ornithischians. Princeton University Press.

    Source of the mass and hip height estimates.

    jones2026a
  7. Madzia, D.; Arbour, V. M.; Boyd, C. A.; Farke, A. A.; Cruzado-Caballero, P.; Evans, D. C. (2021). The phylogenetic nomenclature of ornithischian dinosaurs. PeerJ 9: e12362. doi:10.7717/peerj.12362

    Lists Cumnoria prestwichii in the composition of both Camptosauridae and Styracosterna, under different reference phylogenies.

    madzia2021a
  8. McDonald, A. T. (2011). The taxonomy of species assigned to Camptosaurus (Dinosauria: Ornithopoda). Zootaxa 2783(1). Magnolia Press. doi:10.11646/zootaxa.2783.1.4

    Removes the species from Camptosaurus and recovers it among the most basal members of Styracosterna.

    mcdonald2011a
  9. Fonseca, A. O.; Reid, I. J.; Venner, A.; Duncan, R. J.; Garcia, M. S.; Müller, R. T. (2024). A comprehensive phylogenetic analysis on early ornithischian evolution. Journal of Systematic Palaeontology 22: 2346577. doi:10.1080/14772019.2024.2346577

    Recovers Cumnoria within Camptosauridae, and reviews the analyses placing it near or outside the root of Ankylopollexia.

    fonseca2024a
  10. Dieudonné, P.; Becerra, M. G.; Zanesco, T.; Tortosa, T.; Cruzado-Caballero, P.; Stein, K.; Torcida Fernández-Baldor, F. (2026). Foskeia pelendonum, a new rhabdodontomorph from the Lower Cretaceous of Salas de los Infantes (Burgos Province, Spain), and a new phylogeny of ornithischian dinosaurs. Papers in Palaeontology 12(1). Wiley. doi:10.1002/spp2.70057

    Recovers Cumnoria and Oblitosaurus as sister taxa among the early-diverging ankylopollexians.

    dieudonné2026a
  11. Poole, K. E. (2022). Phylogeny of iguanodontian dinosaurs and the evolution of quadrupedality. Palaeontologia Electronica 25(3): a30. doi:10.26879/702

    Pruned Cumnoria from the strict consensus as an unstable taxon.

    poole2022a
  12. Maidment, S. C. R.; Chapelle, K. E. J.; Bonsor, J. A.; Button, D.; Barrett, P. M. (2023). Osteology and relationships of Cumnoria prestwichii (Ornithischia: Ornithopoda) from the Late Jurassic of Oxfordshire, UK. Monographs of the Palaeontographical Society 176(664): 1-55. doi:10.1080/02693445.2022.2162669

    Redescribes the holotype, diagnoses Cumnoria on two autapomorphies of the pectoral girdle, and places it as a non-ankylopollexian iguanodontian just outside Ankylopollexia.

    maidment2023a
  13. Carpenter, K.; Lamanna, M. C. (2015). The braincase assigned to the ornithopod dinosaur Uteodon McDonald, 2011, reassigned to Dryosaurus Marsh, 1894: implications for iguanodontian morphology and taxonomy. Annals of Carnegie Museum 83(2): 149-165. Carnegie Museum of Natural History. doi:10.2992/007.083.0201

    Regards Cumnoria as a junior subjective synonym of Camptosaurus and returns the species to that genus as Camptosaurus prestwichii.

    carpenter2015a
  14. Sánchez-Fenollosa, S.; Verdú, F. J.; Cobos, A. (2023). The largest ornithopod (Dinosauria: Ornithischia) from the Upper Jurassic of Europe sheds light on the evolutionary history of basal ankylopollexians. Zoological Journal of the Linnean Society 199(4): 1013-1033. Oxford University Press (OUP). doi:10.1093/zoolinnean/zlad076

    Recovers a monophyletic Camptosauridae and follows the referral of Cumnoria to Camptosaurus.

    sánchez-fenollosa2023a
  15. Rotatori, F. M.; Chiarenza, A. A.; Fanti, F.; Moreno-Azanza, M. (2026). The early origin of Iguanodontia: new insights into the macroevolution, diversity and biogeography of the clade. Palaeontology 69(2): e70057. doi:10.1111/pala.70057

    Reviews both treatments of the genus and retains Cumnoria as distinct.

    rotatori2026a