Genus

Valid Extinct

Istiorachis

Lockwood et al. 2025

Istiorachis is an extinct genus of iguanodontian ornithopod dinosaur from the Early Cretaceous Wessex Formation of the Isle of Wight, England. The genus contains a single species, Istiorachis macarthurae, known from a partial postcranial skeleton including several vertebrae, incomplete ribs, and part of the pelvis. Its vertebral neural spines are notably elongated, giving the animal a 'sail-backed' appearance.

Temporal range

Triassic

Jurassic

Cretaceous

Paleogene

Neogene

252 201 145 66 0 Ma

PBDB occurrences

Group

Dinosaures

Herbivore Ground dwelling, gregarious Terrestrial

click to enlarge

Istiorachis macarthurae holotype (MIWG 6643). The anterior-most seven caudal vertebrae in left lateral view with neural spines reconstructed. Abbreviations: Cd, caudal vertebra; SC, sacrocaudal. Scale bar represents 50 mm. © J. A. F. Lockwood, D. M. Martill & S. C. R. Maidment · CC BY 4.0 · Wikimedia

PBDB ↗ Wikipedia ↗

Classification

Dinosauria Unranked clade

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Ornithischia Unranked clade

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Neornithischia Unranked clade

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Pyrodontia Unranked clade

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Cerapoda Unranked clade

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Ornithopoda Suborder

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Iguanodontia Infraorder

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Euiguanodontia Unranked clade

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Dryomorpha Unranked clade

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Ankylopollexia Unranked clade

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Styracosterna Unranked clade

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Istiorachis Genus

Fossil sites 1 geolocated sites

Distribution

Top countries

🇬🇧 United Kingdom

Geological formations

Wessex

Temporal distribution

Hauterivian (132.6–125.77 Ma)

Species (1)

Istiorachis macarthurae 133 Ma

Images 1

Bibliography

Original description

J. A. F. Lockwood, D. M. Martill, and S. C. R. Maidment. 2025. The origins of neural spine elongation in iguanodontian dinosaurs and the osteology of a new sail‐back styracosternan (Dinosauria, Ornithischia) from the Lower Cretaceous Wealden Group of England. Papers in Palaeontology 11(4):e70034:1-38 DOI ↗

Bibliography (1)

Istiorachis

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