Cardiodon

''Cardiodon'' (meaning "heart tooth", in reference to the shape) was a herbivorous genus of sauropod dinosaur, based on a tooth from the late Bathonian-age Middle Jurassic Forest Marble Formation of Wiltshire, England. Historically, it is very obscure and usually referred to '' Cetiosaurus'', but recent analyses suggest that it is a distinct genus, and possibly related to '' Turiasaurus''. ''Cardiodon'' was the first sauropod genus named.Taylor, Michael P., 2010, "Sauropod dinosaur research: a historical review", pp. 361-386 in: Richard T. J. Moody, Eric Buffetaut, Darren Naish and David M. Martill (eds.), ''Dinosaurs and Other Extinct Saurians: a Historical Perspective''. Geological Society of London, Special Publication 343

History and taxonomy

Richard Owen named the genus for a now-lost tooth, part of the collection of naturalist Joseph Chaning Pearce, found near Bradford-on-Avon, but did not assign it a specific name at the time. The generic name is derived from Greek καρδία, ''kardia'', "heart", and ὀδών, ''odon'', "tooth", in reference to its heart-shaped profile.Owen, R. (1841). Odontography, Part II. ''Hippolyte Baillière.'' 655 p. A few years later, in 1844, he added the specific name ''rugulosus'', meaning "wrinkled" in Latin.Owen, R. (1844). Odontography, Part III. ''Hippolyte Baillière.'' 655 p. ''Cardiodon'' was the first sauropod given a formal name to, though Owen was at the time completely unaware of the sauropod nature of the find.

Within a few decades, he and others were viewing ''Cardiodon'' as a possible synonym of his most well-known sauropod genus, '' Cetiosaurus''.Phillips, J. (1871). ''Geology of Oxford and the Valley of the Thames''. Clarendon Press:Oxford, 529 p.Owen, R. (1875). Monographs of the fossil Reptilia of the Mesozoic formations (part III) (genera ''Bothriospondylus'', ''Cetiosaurus'', ''Omosaurus''). Palaeontographical Society Monographs 29:15-93. Richard Lydekker formalized this view in a roundabout way in 1890, by assigning ''Cetiosaurus oxoniensis'' to ''Cardiodon'' on the basis of teeth from Oxfordshire associated with a skeleton of ''C. oxoniensis''.Lydekker, R. (1890). Suborder Sauropoda. In: Lydekker, R. (ed.). ''Catalogue of the Fossil Reptile and Amphibia of the British Museum (Natural History).'' Part 1. Taylor and Francis:London, p. 131-152. He also added a second tooth (BMNH R1527) from the Great Oolite near Cirencester, Gloucestershire. More typically, ''Cardiodon'' has been assigned to ''Cetiosaurus'', sometimes as a separate species ''Cetiosaurus rugulosus'',Steel, R. (1970). Part 14. Saurischia. ''Handbuch der Paläoherpetologie/Encyclopedia of Paleoherpetology''. Part 14. Gustav Fischer Verlag:Stuttgart, p. 1-87. in spite of its priority.

In 2003, Paul Upchurch and John Martin, reviewing ''Cetiosaurus'', found that there is little evidence to assign the ''C. oxoniensis'' teeth to the skeleton, and the "''C. oxoniensis''" teeth differ from the ''Cardiodon'' teeth (''Cardiodon'' teeth are convex facing the tongue); therefore, they supported ''Cardiodon'' being retained as its own genus.Upchurch, P.M., and Martin, J. (2003). The anatomy and taxonomy of ''Cetiosaurus'' (Saurischia, Sauropoda) from the Middle Jurassic of England. ''Journal of Vertebrate Paleontology'' 23(1):208-231. Upchurch ''et al.'' (2004) repeated this assessment, and found that though the teeth have no known autapomorphies, they are those of a eusauropod.Upchurch, P.M., Barrett, P.M., and Dodson, P. (2004). Sauropoda. In: Weishampel, D.B., Dodson, P., and Osmólska, H. (eds.). ''The Dinosauria'' (2nd edition). University of California Press:Berkeley, p. 259-322. More recently, Royo-Torres ''et al.'' (2006), in their description of '' Turiasaurus'', pointed out ''Cardiodon'' as a possible relative to their new, giant sauropod, placing it in the Turiasauria.Royo-Torres, R., Cobos, A., and Alcalá, L. (2006). A giant European dinosaur and a new sauropod clade. ''Science'' 314:1925-1927. Earlier, ''Cardiodon'' had been usually assigned to the Cetiosauridae or a Cardiodontidae of its own.

Description

The original tooth shows, as far as can be deduced from the surviving illustrations, the rare combination of being spatulate and having a convex inner side, though the convexity is slight. Its crown is short and wide, slightly curving to the inside. The outer side is strongly convexly curved from the front to the rear. On this side a shallow groove is present, running parallel to the rear edge. The crown tapers towards its tip. The edges have no denticles. The enamel shows the little wrinkles to which the specific name refers.

Paleobiology

As a sauropod, ''Cardiodon'' would have been a large, quadrupedal herbivore, but because of the scanty remains, much more cannot be said.

References

External links

Darren Naish's reaction to ''Turiasaurus''

{{Taxonbar, from=Q1256846

Turiasauria
Bathonian life
Middle Jurassic dinosaurs of Europe
Jurassic England
Fossils of England
Fossil taxa described in 1841
Taxa named by Richard Owen