Calamospondylus

Taxonomy

Discovery and naming

The type specimen of Calamospondylus, consisting of a 15.2 cm long sacrum preserving five vertebrae and assorted "iliac bones", was collected by the Rev. William Fox in 1865, in Isle of Wight sediments from the Wessex Formation. It was described anonymously by Fox the following year, making it the earliest named small Wealden Group theropod. The genus name Fox provided, Calamospondylus, derives from the Ancient Greek kalamos ("reed"), and spondylus ("vertebra"), and was named "from the fact of its backbones being hollow, smooth, and compact like a reed". The species name honours Sir Richard Owen. Though at one point regarded as a nomen nudum (naked name), given its publication in an informal source (The Athenaeum), the name C. oweni satisfies the criteria of the International Commission on Zoological Nomenclature in that it was accompanied by a description. Said description is, however, terse and lacks figures, and thus little is known of the anatomy of the specimen, as it has since been lost. It was included within a larger body of text which appears to have been written not by Fox himself, but by an editor of The Athenaeum, as it refers to Fox in the third-person. In the section written by Fox, he suggested, based on the fact that C. oweni's bones were hollow and extensively pneumatised, that it was arboreal, leaping between trees, or perhaps saltatorial, "bounding from the grasp of other reptiles" like a grasshopper; this marks one of the earliest speculations on arboreal habits in non-avian dinosaurs.

Validity

In 1889, Richard Lydekker independently assigned the name Calamospondylus to another Wessex Formation dinosaur, which he named C. foxi after Reverend Fox. Upon becoming aware of Fox's Calamospondylus, he renamed the genus to Calamosaurus in 1891. This initial error led to significant confusion over the years, though it was not the only factor. Some confusion emerged over the identity of the type specimen, which was not specified in Fox's description. Various authors have concluded that it was the same specimen that served as the holotype for another Wessex coelurosaur, Aristosuchus, and the name Aristosuchus would thus take priority. However, there exist discrepancies in both size and morphology between the two specimens, and correspondence between Richard Owen and Reverend Fox demonstrates that they were distinct specimens. With that said, the validity of Calamospondylus is uncertain to begin with. The specimen has been lost, and the few characters used to diagnose C. oweni (the presence of five fused sacral vertebrae, a small body size, bones which are more hollow than those of modern birds, and the presence of foramina in at least some of those bones) are not unique to that genus. Therefore, in 2002, Darren Naish rendered Calamospondylus oweni a nomen dubium.

References

References

1. Naish, D. (2011). Theropod dinosaurs. In Batten, D. J. (ed.) English Wealden Fossils. ''The Palaeontological Association'' (London), pp. 526–559.
2. Anonymous (Fox, W.) (1866). "Another new Wealden reptile." ''The Athenaeum'', '''2014''': 740.
3. Naish, D. (2002). The historical taxonomy of the Lower Cretaceous theropods (Dinosauria) ''Calamospondylus'' and ''[[Aristosuchus]]'' from the Isle of Wight. ''Proceedings of the Geologists' Association'' '''113''': 153-163.
4. Naish, 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. {{ISBN. 0-901702-72-2
5. Creisler, Ben. (July 7, 2003). "Dinosauria Translation and Pronunciation Guide C". Dinosauria On-Line.
6. Naish, D.. (2000). "Theropod dinosaurs in the trees: a historical review of arboreal habits amongst nonavian dinosaurs.". Archaeopteryx.
7. Lydekker, R.. (1889). "VIII.—On a Cœluroid Dinosaur from the Wealden". Geological Magazine.
8. Lydekker, R.. (1891). "On certain Ornithosaurian and Dinosaurian Remains". Quarterly Journal of the Geological Society.
9. A. S. Woodward and C. D. Sherborn. (1890). A Catalogue of British Fossil Vertebrata. Dulao & Company, London 1-396.
10. Swinton, W.E. (1936). The dinosaurs of the Isle of Wight. ''Proceedings of the Geologists’ Association'', 47, 204–220.
11. Steel, R. (1970). Encyclopedia of Paleoherpetology, Part 14: Saurischia. Gustav Fischer Verlag, Stuttgart.