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Mantellisaurus

Paul, 2007 man-tell-i-SOR-us

Named for Gideon Mantell, the English geologist and paleontologist who first described Iguanodon, combined with Greek '-saurus' meaning 'lizard'.

125.8–113.2 million years ago Barremian–Aptian, Early Cretaceous
Early Cretaceous stages

Mantellisaurus is a genus of iguanodontian dinosaur that lived in the Barremian and early Aptian ages of the Early Cretaceous Period of Europe. Its remains are known from Belgium (Bernissart), England, Spain and Germany. The type and only species is M. atherfieldensis. Formerly known as Iguanodon atherfieldensis, the new genus Mantellisaurus was erected for the species by Gregory Paul in 2007. According to Paul, Mantellisaurus was more lightly built than Iguanodon and more closely related to Ouranosaurus, making Iguanodon in its traditional sense paraphyletic. It is known from many complete and almost complete skeletons. The genus name honors Gideon Mantell, the discoverer of Iguanodon.

Under dispute

Lockwood and colleagues (2024) recover Mantellisaurus atherfieldensis in a monophyletic Iguanodontidae with Iguanodon, Barilium and Comptonatus. Bonsor and colleagues (2023), scoring the taxon from the holotype alone, instead recover it as an early diverging hadrosauroid outside Iguanodontidae, and both studies describe relationships among these taxa as weakly supported and unstable.

Diagnosis

  1. Tabulate lacrimal process of the maxilla, situated posterior to the ascending process in lateral view.
  2. Pronounced, hook-shaped scapular acromion process with an acute internal angle.
  3. Prominent dorsal ridge on the anterior end of the nasal process of the premaxilla.

Species

Mantellisaurus atherfieldensis (Hooley, 1925)

Type species

First named as Iguanodon atherfieldensis

Named for Atherfield, a village on the southwest shore of the Isle of Wight, England, where the holotype fossil was discovered.

Holotype
NHMUK PV R 5764 , Natural History Museum
Material
Mostly complete (~80%) skeleton with much of the skull, cervical to caudal vertebrae with ribs and chevrons, scapula, coracoid, sternals, forelimbs, ilia, partial pubes and ischia, hindlimbs, and pedes.
Horizon
Vectis Formation, Barremian–Aptian, Early Cretaceous , 125.8–113.2 million years ago
Locality
Brighstone Bay, between Shepherd's Chine and Atherfield Point, Isle of Wight, United Kingdom

Synonyms

  • Iguanodon atherfieldensis reassigned

    Original combination established by Hooley (1925) for the gracile Wealden iguanodontian. Paul (2007) placed the species in the new genus Mantellisaurus, and Norman (2010) formally removed it from Iguanodon.

  • Mantellodon junior subjective

    M. carpenteri is now considered referable to Mantellisaurus atherfieldensis.

Synonyms of the genus

Name Type Reason
Dollodon junior subjective McDonald (2012) found no discrete differences between the Dollodon bampingi skeleton and Mantellisaurus atherfieldensis and referred it to the latter; Norman (2013) reached the same result independently, holding the name undiagnosable as well as synonymous.
Heterosaurus junior subjective Initially described as its own genus in 1850 and later reassigned to Iguanodon; subsequent study placed the material in Mantellisaurus.
Proplanicoxa junior subjective Originally referred to Vectisaurus valdensis and later re-erected as Proplanicoxa; with Vectisaurus now considered a juvenile of Mantellisaurus, Proplanicoxa is also treated as a junior synonym.
Vectisaurus junior subjective Now generally interpreted as a juvenile individual of Mantellisaurus.

Notable specimens

  • Maidstone specimen

    NHMUK PV R 3741 Natural History Museum Found 1834 by William Harding Bensted historic

    Found in a Maidstone quarry in February 1834 and acquired by Gideon Mantell, who identified it as Iguanodon from its teeth. It was used in the first skeletal reconstructions and artistic renderings of Iguanodon, later excluded from Iguanodon and referred to Mantellisaurus.

    Mantell (1834)McDonald (2012)Norman (2013)

References

  1. Paul, G. S. (2007). Turning the old into the new: a separate genus for the gracile iguanodont from the Wealden of England. Horns and Beaks: Ceratopsian and Ornithopod Dinosaurs 69-77. Indiana University Press. paul2007a
  2. Bonsor, J. A.; Lockwood, J. A. F.; Leite, J. V.; Scott-Murray, A.; Maidment, S. C. R. (2023). The osteology of the holotype of the British iguanodontian dinosaur Mantellisaurus atherfieldensis. Monographs of the Palaeontographical Society 177(665): 1-63. doi:10.1080/02693445.2023.2234156

    Detailed osteological monograph of the holotype NHMUK PV R 5764 with an emended three-character diagnosis; finds prior Paul and Norman diagnoses non-autapomorphic.

    bonsor2023a
  3. Jones, B. (2026). The Princeton Encyclopedia of Dinosaurs: Ornithischians. Princeton University Press.

    Source of the body length and hip height estimates, and the appearance features.

    jones2026a
  4. Mantell, G. A. (1834). Discovery of the bones of the Iguanodon in a quarry of Kentish Rag (a limestone belonging to the Lower Greensand Formation) near Maidstone, Kent. Edinburgh New Philosophical Journal 17: 200-201. mantell1834a
  5. McDonald, A. T. (2012). The status of Dollodon and other basal iguanodonts (Dinosauria: Ornithischia) from the upper Wealden beds (Lower Cretaceous) of Europe. Cretaceous Research 33(1): 1-6. doi:10.1016/j.cretres.2011.03.002 mcdonald2012b
  6. Norman, D. B. (2013). On the taxonomy and diversity of Wealden iguanodontian dinosaurs (Ornithischia: Ornithopoda). Revue de Paléobiologie, Genève 32(2): 385-404. norman2013a
  7. 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

    Grouped Mantellisaurus with Iguanodon, Barilium, and Comptonatus in Iguanodontidae.

    lockwood2024a
  8. Hooley, R. W. (1925). On the skeleton of Iguanodon atherfieldensis sp. nov., from the Wealden shales of Atherfield (Isle of Wight). Quarterly Journal of the Geological Society of London 81(321): 1-61. doi:10.1144/gsl.jgs.1925.081.01-04.02 hooley1925a
  9. 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