Open Paleo

Cetiosaurus

Owen, 1841 see-TIE-o-SAWR-us /ˌsiːtioʊˈsɔːrəs, ˌsiːʃi-/

From Greek keteios/ketos ('sea monster', later 'whale') + sauros ('lizard'), meaning 'whale lizard'. Named by Richard Owen who initially believed it was a large marine creature.

170.9–165.3 million years ago Bajocian–Bathonian, Middle Jurassic
Middle Jurassic stages

Cetiosaurus is a genus of herbivorous sauropod dinosaur from the Middle Jurassic Period, living about 171 to 165 million years ago during the Bajocian and Bathonian ages in what is now Britain and probably France.

Diagnosis

  1. Posterior cervical and anterior dorsal neural spines symmetrically pyramid-shaped, with laminae nearly equal about both the sagittal and transverse planes
  2. Spinodiapophyseal lamina lost (or completely fused with the spinopostzygapophyseal lamina) on all dorsal neural spines
  3. Distal caudal centra with tongue-like projections at the dorsal margin of the articular faces, extending the floor of the neural canal anteroposteriorly
  4. Distal shafts of the anterior chevrons anteroposteriorly compressed, not tapering to a transversely flattened distal end
  5. A triangular hollow, bounded dorsally by a horizontal ridge, on the lateral surface of the base of the pubic process of the ilium

Species

Cetiosaurus oxoniensis Phillips, 1871

Type species

Named for Oxford (Latin 'Oxonia'), the county where the type specimens were discovered by Professor John Phillips in 1868-1870.

Lectotype
OUMNH PAL-J.013605 , Oxford University Museum of Natural History
Material
A partial skeleton: dorsal and sacral fragments, thoracic ribs, about 30 caudal centra, hemal arches, scapulae, coracoids, a sternal plate, humeri, ulnae, ilia, pubis, ischium, and hind limb bones.
Horizon
Forest Marble Formation, Bajocian–Bathonian, Middle Jurassic , 170.9–165.3 million years ago
Locality
Bletchingdon Station, Oxfordshire, United Kingdom

Synonyms of the genus

Name Type Reason
Ceteosaurus junior objective Variant spelling. Phillips (1871) writes Ceteosaurus throughout the monograph that describes the type species, and Upchurch and Martin (2003) list "Ceteosaurus oxoniensis Phillips, 1871" in its synonymy.

Notable specimens

  • Rutland Dinosaur

    LCM G468.1968 Leicester Museum & Art Gallery complementary

    Referred C. oxoniensis skeleton, about 40 percent complete and the most complete sauropod fossil found in the United Kingdom. It preserves a nearly complete cervical series (2-14), greatly extending known anatomy, especially the neck, absent in the type material. On display since 1985.

    Jones (1970)

ICZN cases

References

  1. Owen, R. (1841). Description of a portion of the skeleton of the Cetiosaurus, a gigantic extinct saurian reptile occurring in the Oolitic formations of different portions of England. Proceedings of the Geological Society of London 3, part 2(80): 457-462. owen1841a
  2. Phillips, J. (1871). Geology of Oxford and the Valley of the Thames. 1-523. Clarendon Press.

    Names Cetiosaurus oxoniensis, later designated the type species of Cetiosaurus under ICZN Opinion 2331.

    phillips1871a
  3. Upchurch, P.; Martin, J. (2003). The anatomy and taxonomy of Cetiosaurus (Saurischia, Sauropoda) from the Middle Jurassic of England. Journal of Vertebrate Paleontology 23(1): 208-231. doi:10.1671/0272-4634(2003)23[208:TAATOC]2.0.CO;2

    Redescription of Cetiosaurus; designates the lectotype of C. oxoniensis and provides the modern diagnosis.

    upchurch2003a
  4. Upchurch, P.; Martin, J.; Taylor, M. (2009). Case 3472. Cetiosaurus Owen, 1841 (Dinosauria, Sauropoda): proposed conservation of usage by designation of Cetiosaurus oxoniensis Phillips, 1871 as the type species. Bulletin of Zoological Nomenclature 66(1): 51-55. doi:10.21805/bzn.v66i1.a6

    Petition to the ICZN to fix C. oxoniensis as the type species.

    upchurch2009a
  5. International Commission on Zoological Nomenclature (2014). Opinion 2331 (Case 3472). Cetiosaurus Owen, 1841 (Dinosauria, Sauropoda): usage conserved by designation of Cetiosaurus oxoniensis Phillips, 1871 as the type species. Bulletin of Zoological Nomenclature 71(1): 48-50. International Trust for Zoological Nomenclature.

    Resolves Case 3472. Designates C. oxoniensis as the type species, conserving usage of Cetiosaurus.

    iczn2014a
  6. Jones, M. D. (1970). Cetiosaurus oxoniensis, a middle Jurassic sauropod from Rutland, England. Transactions of the Leicester Literary & Philosophical Society 64: 144-150. jones1970a
  7. Jones, B. (2026). The Princeton Encyclopedia of Dinosaurs: Sauropods. Princeton University Press.

    Source of the hip height estimate.

    jones2026b