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Dacentrurus

Lucas, 1902 da-sen-TROOR-us

From Greek dakno ('to bite' or 'pointed') + oura ('tail'), meaning 'tail full of points', referring to the spikes on the animal's tail.

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

Dacentrurus is an extinct genus of stegosaurian dinosaur from the Late Jurassic and perhaps Early Cretaceous (154-140 million years ago) of Europe. Its type species, D. armatus, was named in 1875 as Omosaurus armatus, based on a skeleton found in a clay pit in the Kimmeridge Clay in Swindon, England. In 1902 the genus was renamed Dacentrurus because the name Omosaurus had already been used for a phytosaur in 1856. After 1875, half a dozen other species would be named but perhaps only Dacentrurus armatus is valid.

Diagnosis

  1. Humerus remarkably broad relative to length, especially at proximal half, with an unusually prominent anconal tuberosity and ridge (tricipital crest) absent or rudimentary in all other dinosaurs described by Owen.
  2. Deep anconal depression at distal expansion of humerus, exceeding that of any other known Dinosaurian, Crocodilian, or Lacertian humerus.
  3. Osseous dermal spine obliquely truncate at base with coarse marginal notching and paired vascular channels; elliptical in cross-section with central medullary canal; provision for attachment stronger than in Hylaeosaurus.
  4. Ilium with distinctive superacetabular plate and ridge continuing onto outer surface of antacetabular prolongation, imparting a triedral form to that part of the bone.
  5. Ischium extremely slender (styliform) relative to its length, with no process crossing the obturator interspace between ischium and pubis.
  6. Pubis contributing no discernible share to the acetabular cavity; proximal end articulating only with the ischium, not with the ilium (Crocodilian character).

Species

Dacentrurus armatus (Owen, 1875)

Type species

First named as Omosaurus armatus

From Latin 'armatus' meaning 'armed', referring to a large spike Owen assumed was present on the upper arm of the holotype.

Holotype
NHMUK PV OR 46013 , Natural History Museum
Material
Partial skeleton of a single individual: vertebral column, pelvis, right femur, a left fore limb (humerus, radius, ulna, carpus, metacarpals, phalanges), a tibia, and one dermal spine
Horizon
lower Kimmeridge Clay Formation, Kimmeridgian, Late Jurassic , 154.8–149.2 million years ago
Locality
Swindon Brick and Tile Company brick pit, Wiltshire, United Kingdom

Synonyms of the genus

Name Type Reason
Omosaurus preoccupied Name preoccupied by Omosaurus (Crocodilia).

References

  1. Owen, R. (1875). Monographs on the fossil Reptilia of the Mesozoic formations. Part II (Genera Bothriospondylus, Cetiosaurus, Omosaurus). 15-93. Printed for the Palaeontographical Society.

    Original description, as Omosaurus armatus.

    owen1875a
  2. Lucas, F. A. (1902). Paleontological notes. The generic name Omosaurus. A new generic name for Stegosaurus marshi. Science, new series 16(402): 435. doi:10.1126/science.16.402.435

    Replacement name Dacentrurus for the preoccupied Omosaurus Owen, 1875.

    lucas1902a
  3. Jones, B. (2026). The Princeton Encyclopedia of Dinosaurs: Ornithischians. Princeton University Press.

    Source of the appearance features.

    jones2026a
  4. 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

    Gives the holotype's provenance as "Kimmeridge Clay (Kimmeridgian: Late Jurassic), Swindon, Wiltshire".

    maidment2008a
  5. Sánchez-Fenollosa, S.; Cobos, A. (2025). New insights into the phylogeny and skull evolution of stegosaurian dinosaurs: an extraordinary cranium from the European Late Jurassic (Dinosauria: Stegosauria). Vertebrate Zoology 75: 165-189. doi:10.3897/vz.75.e146618

    Places the holotype in the lower part of the Kimmeridge Clay Formation.

    sánchez-fenollosa2025a
  6. Galton, P. M. (1985). British plated dinosaurs (Ornithischia, Stegosauridae). Journal of Vertebrate Paleontology 5(3): 211-254. doi:10.1080/02724634.1985.10011859

    Gives the type locality as the brick-pit of Swindon Brick and Tile Co. at the foot of Old Swindon Hill, with a grid reference; says the exact horizon is not known.

    galton1985d