Open Paleo

Thecocoelurus

Huene, 1923 THEE-ko-see-LOO-rus Nomen dubium

A contraction of the genus names Thecospondylus and Coelurus, translating to 'sheathed hollow form', reflecting the specimen's dual taxonomic history under those two genera

125.8–121.4 million years ago Barremian, Early Cretaceous
Early Cretaceous stages

Thecocoelurus is a genus of theropod dinosaur from the early Cretaceous period of England. Its type specimen was discovered in strata from the Wessex Formation on the Isle of Wight by the Reverend William Fox, and after Fox's death, it, alongside the rest of the Fox collection, became the property of the British Museum of Natural History. The specimen was named in 1888 by Harry Govier Seeley, who assigned it to the genus Thecospondylus . In 1901, it was reassigned by Baron Franz Nopcsa to Coelurus. In 1923, the specimen was removed from either genus by Friedrich von Huene, who assigned it to a genus of its own. Thecocoelurus currently consists of one species, T. daviesi. The validity of the genus has been questioned, with a 2001 publication finding it to be a nomen dubium.

Under dispute

Thecocoelurus is based on half of a cervical vertebra that lacks diagnostic characters, and its affinity is contested. Naish and Martill (2002, 2007) found it most similar to caenagnathid oviraptorosaurs. Allain and colleagues (2014) referred the holotype to Ornithomimosauria on a pneumatic recess shared with the Angeac-Charente theropod, a character they note also occurs in modified form in the noasaurid Masiakasaurus. Cau and Paterna (2025) have since recovered the Angeac-Charente theropod within Abelisauroidea.

Species

Thecocoelurus daviesi Huene, 1923 Nomen dubium

Type species

Named in honor of William Davies (1814-1891), a paleontologist at the British Museum (Natural History).

Holotype
NHMUK PV R 181 , Natural History Museum
Material
Partial cervical vertebra.
Horizon
Wessex Formation, Barremian, Early Cretaceous , 125.8–121.4 million years ago
Locality
Isle of Wight, United Kingdom

References

  1. Huene, F. V. (1923). Carnivorous Saurischia in Europe since the Triassic. Bulletin of the Geological Society of America 34: 449-458. doi:10.1130/gsab-34-449 huene1923a
  2. Allain, R.; Vullo, R.; Le Loeuff, J.; Tournepiche, J. F. (2014). European ornithomimosaurs (Dinosauria, Theropoda): an undetected record. Geologica Acta 12(2): 127-135. doi:10.1344/105.000002083

    Treats Thecocoelurus as a nomen dubium but refers the holotype to Ornithomimosauria on comparison with the Angeac-Charente theropod.

    allain2014a
  3. Naish, D.; Hutt, S.; Martill, D. M. (2001). Saurischian dinosaurs 2: theropods. Dinosaurs of the Isle of Wight (Martill, D. M.; Naish, D., eds.) 10: 242-309. The Palaeontological Association, London.

    Regarded Thecocoelurus as a nomen dubium given its fragmentary remains.

    naish2001a
  4. Naish, D.; Martill, D. M. (2002). A reappraisal of Thecocoelurus daviesi (Dinosauria: Theropoda) from the Early Cretaceous of the Isle of Wight. Proceedings of the Geologists' Association 113(1): 23-30. Elsevier BV. doi:10.1016/S0016-7878(02)80003-7

    Finds the holotype undiagnostic, making the name a nomen dubium, and most similar to the cervical vertebrae of caenagnathid oviraptorosaurs.

    naish2002b
  5. Naish, D.; Martill, D. M. (2007). Dinosaurs of Great Britain and the role of the Geological Society of London in their discovery: basal Dinosauria and Saurischia. Journal of the Geological Society 164(3): 493-510. doi:10.1144/0016-76492006-032

    Holds that, lacking autapomorphies, T. daviesi should not be regarded as a valid taxon, though it indicates caenagnathid-like oviraptorosaurs in the English Lower Cretaceous.

    naish2007a
  6. Allain, R.; Vullo, R.; Rozada, L.; Anquetin, J.; Bourgeais, R.; Goedert, J.; Lasseron, M.; Martin, J. E.; Pérez-García, A.; Peyre de Fabrègues, C.; Royo-Torres, R.; Augier, D.; Bailly, G.; Cazes, L.; Despres, Y.; Gailliègue, A.; Gomez, B.; Goussard, F.; Lenglet, T.; Vacant, R.; Mazan; Tournepiche, J. F. (2022). Vertebrate paleobiodiversity of the Early Cretaceous (Berriasian) Angeac-Charente Lagerstätte (southwestern France): implications for continental faunal turnover at the J/K boundary. Geodiversitas 44(25): 683-752. Muséum national d'Histoire naturelle. doi:10.5252/geodiversitas2022v44a25

    Retains the Angeac-Charente theropod in Ornithomimosauria on an anatomical survey, without a phylogenetic analysis.

    allain2022a
  7. Cau, A.; Paterna, A. (2025). Beyond the Stromer's Riddle: the impact of lumping and splitting hypotheses on the systematics of the giant predatory dinosaurs from northern Africa. Italian Journal of Geosciences 144(2): 162-185. doi:10.3301/IJG.2025.10

    Recovers the Angeac-Charente theropod, the comparison material for the ornithomimosaur referral, within Abelisauroidea.

    cau2025a