Thecocoelurus

''Thecocoelurus'' is a dubious genus of theropod dinosaur from the early Cretaceous period of England. The phylogenetic placement of this genus is uncertain, and it has been referred to an oviraptosaur, an ornithomimosaur, or a therizinosaur by different researchers throughout its history.

Discovery and naming

''Thecocoelurus'' is known only from half of a single cervical vertebra, discovered by the Rev. William Darwin Fox on the Isle of Wight during the 19th century. After his death the ''Fox Collection'' was acquired by the British Museum of Natural History. William Davies was the first to notice the specimen and assumed a close affinity with '' Coelurus''.

It was described by Harry Govier Seeley in 1888. Seeley named the fossil '' Thecospondylus daviesi'', referring it to a genus he had named earlier for the incomplete cast of a sacrum. However, in 1901 Baron Franz Nopcsa renamed it ''Coelurus daviesi''. In 1923 Friedrich von Huene decided that it should be removed from either ''Thecospondylus'' or ''Coelurus'' and given its own genus, ''Thecocoelurus''. The generic name is a contraction of "Thecospondylus" and "Coelurus".

The holotype, NHMUK PV R181, was found in debris from a layer of the Wessex Formation, dating from the Barremian. It consists of the anterior end, about a third, of a cervical vertebra estimated by Seeley to have been nine centimetres long.

Classification

Von Huene originally assigned ''Thecocoelurus'' to the Coeluridae, but in 1926 speculated that due to the not inconsiderable size and typical structure of the vertebra it might belong to a member of the Ornithomimidae. Though it has been since been typically identified as an indeterminate "coelurian" theropod, ''Thecocoelurus'' was reidentified by Darren Naish and colleagues in 2001 as a member of the Oviraptorosauria, a group of omnivorous maniraptoran theropods, which would make it the only oviraptorosaur fossil that has ever been found in Europe. Numerous detailed similarities are shared by the specimen and the cervical vertebrae of caenagnathid oviraptorosaurs. Naish ''et al.'' also considered ''Thecocoelurus'' to be a ''nomen dubium''. In 2004 it was theorized by James Kirkland that ''Thecocoelurus'' might not be an oviraptorosaur, but a member of the therizinosaur lineage instead, closely related to '' Falcarius'', again a unique occurrence for Europe.

A 2014 re-evaluation comparing the specimens with European ornithomimosaur fossils found that ''Thecocoelurus'' was likely one of the oldest known ornithomimosaurs, and a possible senior synonym of ''Valdoraptor''.R. Allain, R. Vullo, J. Le loeuff & J.-F. Tournepiche (2014) European ornithomimosaurs (Dinosauria, Theropoda): an undetected record. Geologica Acta 12(2) (advance online publication) June 2014. However, researchers Micky Mortimer and Darren Naish have expressed doubt on its ornithomimosaur affinities, suggesting instead it may represent a therizinosaur similar to '' Falcarius''.Mortimer, M. (2014, May 26). "Is Thecocoelurus an ornithomimosaur?". Retrieved from http://theropoddatabase.blogspot.co.uk

See also

* Timeline of ornithomimosaur research

References

{{Taxonbar, from=Q1826819

Ornithomimosaurs
Barremian life
Early Cretaceous dinosaurs of Europe
Cretaceous England
Fossils of England
Fossil taxa described in 1923
Taxa named by Friedrich von Huene
Nomina dubia