Thetype specimen,NHMUK PV R 901, consisting of two articulatedcervical (neck)vertebrae,[1] was part of the "Fox collection", a collection of fossils collected by the Rev.William Fox which were given to theNatural History Museum in London on his death. When cataloguing the Fox collection,Richard Lydekker came across these bones and named themCalamospondylus foxi. The name derives from the Ancient Greekkalamos ('reed') andspondylus ('vertebra') and hints at the slender and lightweight build of the vertebrae.[2][3] Unbeknownst to Lydekker, the nameCalamospondylus had already been coined in 1866 (by Reverend Fox himself, the very man honored in Lydekker's species name).[4] Upon realising his mistake, Lydekker promptly renamed it, creating the new combinationCalamosaurus foxi (from the Latinsauros, "lizard") in 1891.[5]
In the same work, Lydekker provisionally assigned the righttibia NHMUK R.186, which was discovered byWilliam D. Fox in 1865 or 1866, toCalamosaurus; this specimen was later identified as being a basal or nonspecific coelurosaur,[6][7][8] possibly a compsognathid,[2] and has more recently been referred to the cladeOrnithomimosauria.[9][10]Darren Naish noted in 2011 that there is "no firm basis" for the assignment of NHMUK R.186 toCalamosaurus.[1]
The initial mistake made by Lydekker has led to immense confusion regarding the validity ofCalamosaurus. Many authors have regarded it as ajunior synonym ofCalamospondylus,[11][12][13] despite the lack of overlapping material.[2] Beyond that, it was subsequently regarded by Lydekker as a synonym ofAristosuchus.[14] Some authors have opted to relegateCalamosaurus to the status of anomen dubium due to its fragmentary condition and ambiguous taxonomy,[2][15][16] although this view is not universal. In 2011, Darren Naish supported the validity of the genus, and noted similarities with the Chinese taxonDilong paradoxus that are indicative of abasal position withinTyrannosauroidea, though did caution against the assignment of further remains to the genus considering its fragmentary state.[1]
In 2001, Darren Naish, Steve Hutt, and David Martill estimated thatCalamosaurus may have reached a body length of 3.5 m (11 ft). Initially, they noted that the fusion of theneural arches to thevertebral centra (the main body of eachvertebra) suggests that it was fully grown at the time of its death;[2] however, in a 2011 work, Naish noted that theneurocentral sutures of the specimen were not fully closed, suggesting that it had not reached full skeletal maturity. He did, however, support the initial size estimate for the specimen.[1] Both of the holotypeCalamospondyluscervical (neck)vertebrae are about 40 mm (1.6 in) in length. They areopisthocoelous, meaning that they are convexanteriorly (towards the front), and concaveposteriorly (towards the rear), with offsetarticular facets, similar to those ofDilong.[1] The cervical vertebrae were at one point interpreted as lackingepipophyses entirely, suggesting a small, lightly built head;[2] whilst they are indeed present, they are very strongly reduced.[1]
A selection of Wessex Formation dinosaurs. On the left isIguanodon. In the foreground is a group ofHypsilophodon being pursued by anEotyrannus. In the right background is aNeovenator. In the midground is a pair of basal ornithomimosaurs.
The holotype ofCalamosaurus heralds from the Wessex Formation.[17]Sedimentological data suggests that the depositional environment of the Wessex Formation was afloodplain intersected byfluvial (river) andlacustrine (lake) deposits. Water levels likely varied throughout the year,[18] due to there being more evaporation than precipitation, though precipitation was regardless quite high. The Wessex seems to have regularly experienced extreme storms[19] and periodic flood events, resulting in debris flows which would have deposited dead organisms in ponds.[20] Burned plant and insect material andfusain suggests that the environment experienced frequentwildfires, stifling for the most part the dense growth ofgymnosperms.[18][20] Much of the flora of the formed of low ground cover, consisting primarily ofpteridophytes, with occasional stands ofconifers,cycads and the tree fernTempskya.[18] Most vertebrate material from the Wessex Formation originates from plant debris beds, resulting from the aforementioned flooding events.[20]
^abcdefNaish, D. 2011. Theropod dinosaurs. In Batten, D. J. (ed.) English Wealden Fossils. The Palaeontological Association (London), pp. 526–559.
^abcdefNaish, D., Hutt, S., and Martill, D.M. (2001). Saurischian dinosaurs 2: theropods. In: Martill, D.M., and Naish, D. (eds.).Dinosaurs of the Isle of Wight. The Palaeontological Association:London, 242-309.ISBN0-901702-72-2
^Fox, W.D. in Anonymous. (1866) Another Wealden reptile.Athenaeum2014:740.
^Lydekker. R. (1891). On certain ornithosaurian and dinosaurian remains.Quarterly Journal of the Geological Society of London47:41-44.
^Norman, D.B., (1990). Problematic Theropoda: “Coelurosaurs”. In: Weishampel, D.B., Dodson, P., Osmolska, H. (eds.). The Dinosauria. Berkeley, University of California Press, 280-305.
^Long, J.A. and Molnar, R.E. (1998). "A new Jurassic theropod dinosaur from Western Australia".Records of the Western Australian Museum 19 (1): 221-229
^Welles, S.P., Long, R.A., (1974). The tarsus of theropod dinosaurs.Annals of the South African Museum, 64, 191-218.
^R. Allain, R. Vullo, J. Le loeuff & J.-F. Tournepiche (2014) European ornithomimosaurs (Dinosauria, Theropoda): an undetected record.Geologica Acta12: (2) (advance online publication) June 2014.
^Swinton, W.E. (1936). The dinosaurs of the Isle of Wight.Proceedings of the Geologists' Association47(3):204-220.
^Romer, A.S. (1956).Osteology of the Reptiles. University of Chicago Press:Chicago, 1-772.ISBN0-89464-985-X
^Steel, R. (1970). Part 14. Saurischia.Handbuch der Paläoherpetologie/Encyclopedia of Paleoherpetology. Part 14. Gustav Fischer Verlag:Stuttgart, 1-87.
^Norman, D.B. (1990). Problematic theropoda: "coelurosaurs". In: Weishampel, D.B., Dodson, P., and Osmólska, H. (eds.).The Dinosauria. University of California Press:Berkeley, 280-305.ISBN0-520-06727-4.
^Holtz Jr., T.R., Molnar, R.E., and Currie, P.J. (2004). Basal Tetanurae. In: Weishampel, D.B., Dodson, P., and Osmólska, H. (eds.).The Dinosauria (second edition). University of California Press:Berkeley, 71-110.ISBN0-520-24209-2.
^Weishampel, David B; et al. (2004). "Dinosaur distribution (Early Cretaceous, Europe)". In: Weishampel, David B.; Dodson, Peter; and Osmólska, Halszka (eds.):The Dinosauria, 2nd, Berkeley: University of California Press. Pp. 556-563.ISBN0-520-24209-2.
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