Calamospondylus

Calamospondylus (meaning "quill vertebrae") is a genus of theropod dinosaur. It lived during the Early Cretaceous and its fossils were found on the Isle of Wight in southern England. The type species is C. oweni.

Discovery and naming
The holotype was collected by William Darwin Fox in 1865 and Calamospondylus oweni was described anonymously by amateur paleontologist William D. Fox in 1866 on the basis of a sacrum and associated pelvic elements found on the Isle of Wight in the layers of the Wessex Formation.

Several authors (e.g. Woodward & Sherborn 1890; Swinton 1936; Steel 1970) regarded Calamospondylus as a nomen nudum for Aristosuchus and therefore based on the same specimen as the Aristosuchus holotype. However, as noted by Naish (2002), size discrepancies between the holotypes of Calamospondylus oweni and Aristosuchus pusillus as well as letters of correspondence between Richard Owen and Reverend William Fox demonstrate that C. oweni is based on a different specimen than Aristosuchus.

A second species, Calamospondylus foxi, was named by Lydekker (1889) and was moved to a separate genus, Calamosaurus, by Lydekker (1891).

More remains have since been found, including fragmentary vertebrae collected by Kai Bailey in 2014 and specimen NHMUK R.186, a tibia. Both specimens are on display at the Dinosaur Expeditions, Conservation and Palaeoart Centre near Brighstone, Isle of Wight.

Specimen NHMUK R.186
NHMUK R.186 was discovered by William D. Fox in 1865 or 1866 and was first assigned to Hypsilophodon foxii by Lydekker (1888). Lydekker (1891) moved NHMUK R.186 to Aristosuchus pusillis, and Galton (1973) agreed with this classification. Welles & Long (1974) referred it to the Ornithomimidae, while Norman (1990), Kirkland et al. (1998) and Long and Molnar (1998) referred NHMUK R.186 to Coelurosauria. Galton and Molnar (2005) noted the similarities of NHMUK R.186 to the holotype of Coelurus fragilis, and Allain et al. (2014) agreed with the placement of NHMUK R.186 within Coelurosauria.

Naish et al. (2001) tentatively referred the tibia to Calamosaurus foxi, and NHMUK R.186 has since been moved to Calamospondylus oweni.

Description
As a possible oviraptorosaurian, Calamospondylus would have been a small, agile, bipedal carnivore. Naish et al. (2001) estimate the living animal would have been around 1 - 2.5 m long.