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Barilium

Norman, 2010 bar-il-ee-um

From Greek barys meaning 'heavy' combined with Latin ilium (the hip bone). Full meaning: 'heavy ilium', referring to the robust hip bone.

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

Barilium is a genus of iguanodontian dinosaur which was first described as a species of Iguanodon (I. dawsoni) by Richard Lydekker in 1888, the specific epithet honoring the discoverer Charles Dawson, who collected the holotype during the 1880s.

Under dispute

Barilium dawsoni is recovered close to Iguanodon and Mantellisaurus, within Hadrosauriformes, in most analyses (Norman, 2015; Verdú and colleagues, 2017; Lockwood and colleagues, 2021, 2024), and Lockwood and colleagues (2024) group the three with Comptonatus in an Iguanodontidae. Other analyses place it below Hadrosauriformes (Boyd and Pagnac, 2015; Párraga and Prieto-Márquez, 2019; Bertozzo and colleagues, 2025), and several on the McDonald matrix leave it unresolved at the base of the clade.

Diagnosis

  1. Rim of the sacrodorsal rib facet visible in lateral view in the upper part of the recess between the preacetabular process and the pubic peduncle (autapomorphy).
  2. Lateral surface of the preacetabular process twists axially to face dorsally toward its anterior end (autapomorphy).
  3. Dorsal edge of the acetabular blade is flattened and transversely thick (autapomorphy).
  4. Very restricted brevis shelf (fossa) not bounded by a prominent lateral ridge (autapomorphy).
  5. Posterior dorsal vertebrae have spool-shaped cylindrical centra with thin everted articular margins and transversely rounded haemal surfaces (autapomorphy).
  6. Proximal caudal vertebrae have broad, dorsoventrally compressed centra (subrectangular in anterior view) (autapomorphy).

Species

Barilium dawsoni (Lydekker, 1888)

Type species

First named as Iguanodon dawsoni

Named for Charles Dawson, who collected the holotype during the 1880s.

Holotype
NHMUK PV R 798 , Natural History Museum
Material
Partial skeleton.
Horizon
Wadhurst Clay Formation, Valanginian, Early Cretaceous , 137.1–132.6 million years ago
Locality
Shornden Quarry, East Sussex, United Kingdom

Synonyms

  • Iguanodon dawsoni reassigned

    Original combination established by Lydekker (1888); reassigned to the new genus Barilium by Norman (2010).

  • Torilion junior objective

    Iguanodon dawsoni was first reassigned to Barilium dawsoni and then independently re-erected as Torilion dawsoni; Torilion is now treated as a junior synonym of Barilium.

Synonyms of the genus

Name Type Reason
Kukufeldia junior subjective Material is indistinguishable from Barilium and is treated as a junior synonym.
Sellacoxa junior subjective Tentatively treated as a junior synonym of Barilium pending further analysis.

References

  1. 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 the type from "Shornden Quarry, St. Leonards (TQ 802106) near Hastings".

    galton2009a
  2. Norman, D. B. (2010). A taxonomy of iguanodontians (Dinosauria: Ornithopoda) from the lower Wealden Group (Cretaceous: Valanginian) of southern England. Zootaxa 2489(1): 47-66. Magnolia Press. doi:10.11646/zootaxa.2489.1.3 norman2010a
  3. Lockwood, J. A. F.; Martill, D. M.; Maidment, S. C. R. (2024). Comptonatus chasei, a new iguanodontian dinosaur from the Lower Cretaceous Wessex Formation of the Isle of Wight, southern England. Journal of Systematic Palaeontology 22(1). Informa UK Limited. doi:10.1080/14772019.2024.2346573

    Recovered Barilium in an Iguanodontidae with Iguanodon, Mantellisaurus and Comptonatus, within Hadrosauriformes.

    lockwood2024a
  4. Jones, B. (2026). The Princeton Encyclopedia of Dinosaurs: Ornithischians. Princeton University Press.

    Reports Barilium as close to Iguanodon and Mantellisaurus.

    jones2026a
  5. Lydekker, R. (1888). Note on a new Wealden iguanodont and other dinosaurs. Quarterly Journal of the Geological Society of London 44(173): 46-61. doi:10.1144/gsl.jgs.1888.044.01-04.08 lydekker1888b
  6. Norman, D. B. (2015). On the history, osteology, and systematic position of the Wealden (Hastings group) dinosaur Hypselospinus fittoni (Iguanodontia: Styracosterna). Zoological Journal of the Linnean Society 173: 92-189. doi:10.1111/zoj.12193

    Recovered Barilium in an iguanodontoid clade with Iguanodon, Mantellisaurus, Proa, Jinzhousaurus and Bolong.

    norman2015a
  7. Verdú, F. J.; Royo-Torres, R.; Cobos, A.; Alcalá, L. (2017). New systematic and phylogenetic data about the early Barremian Iguanodon galvensis (Ornithopoda: Iguanodontoidea) from Spain. Historical Biology 30(4): 437-474. doi:10.1080/08912963.2017.1287179

    Recovered Barilium with the two Iguanodon species in Iguanodontoidea, within Hadrosauriformes.

    verdú2017a
  8. Lockwood, J. A. F.; Martill, D. M.; Maidment, S. C. R. (2021). A new hadrosauriform dinosaur from the Wessex Formation, Wealden Group (Early Cretaceous), of the Isle of Wight, southern England. Journal of Systematic Palaeontology 19(12): 847-888. Informa UK Limited. doi:10.1080/14772019.2021.1978005

    Recovered Barilium within Hadrosauriformes, paired with Iguanodon in the majority-rule tree.

    lockwood2021a
  9. Boyd, C. A.; Pagnac, D. C. (2015). Insight on the anatomy, systematic relationships, and age of the Early Cretaceous ankylopollexian dinosaur Dakotadon lakotaensis. PeerJ 3: e1263. PeerJ. doi:10.7717/peerj.1263

    Recovered Barilium with Lanzhousaurus and Bolong below Hadrosauriformes.

    boyd2015b
  10. Párraga, J.; Prieto-Márquez, A. (2019). Pareisactus evrostos, a new basal iguanodontian (Dinosauria: Ornithopoda) from the Upper Cretaceous of southwestern Europe. Zootaxa 4555(2). Magnolia Press. doi:10.11646/zootaxa.4555.2.5

    Recovered Barilium as the sister of the clade of Hypselospinus, Hippodraco and Hadrosauriformes.

    párraga2019a
  11. Bertozzo, F.; Camilo, B.; Araújo, R.; Manucci, F.; Kullberg, J. C.; Cerio, D. G.; de Carvalho, V. F.; Marrecas, P.; Figueiredo, S. D.; Godefroit, P. (2025). Cariocecus bocagei, a new basal hadrosauroid from the Lower Cretaceous of Portugal. Journal of Systematic Palaeontology 23(1). doi:10.1080/14772019.2025.2536347

    Recovered Barilium in a more basal position, outside Hadrosauriformes, dissolving Iguanodontidae.

    bertozzo2025a