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.[1]

Cardiodon
Temporal range: Middle Jurassic
Cardiodon
Holotype tooth
Scientific classification
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Cardiodon

Owen, 1841
Binomial name
Cardiodon rugulosus
Owen, 1844

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.[2] A few years later, in 1844, he added the specific name rugulosus, meaning "wrinkled" in Latin.[3] 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.[4][5] 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.[6] He also added a second tooth (BMNH R1527) from the Great Oolite near Cirencester, Gloucestershire.[6] More typically, Cardiodon has been assigned to Cetiosaurus, sometimes as a separate species Cetiosaurus rugulosus,[7] 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.[8] Upchurch et al. (2004) repeated this assessment, and found that though the teeth have no known autapomorphies, they are those of a eusauropod.[9] 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.[10] 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.[8]

Paleobiology

As a sauropod, Cardiodon would have been a large, quadrupedal herbivore,[9] but because of the scanty remains, much more cannot be said.

References

  1. ^ 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
  2. ^ Owen, R. (1841). Odontography, Part II. Hippolyte Baillière. 655 p.
  3. ^ Owen, R. (1844). Odontography, Part III. Hippolyte Baillière. 655 p.
  4. ^ Phillips, J. (1871). Geology of Oxford and the Valley of the Thames. Clarendon Press:Oxford, 529 p.
  5. ^ Owen, R. (1875). Monographs of the fossil Reptilia of the Mesozoic formations (part III) (genera Bothriospondylus, Cetiosaurus, Omosaurus). Palaeontographical Society Monographs 29:15-93.
  6. ^ a b 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.
  7. ^ Steel, R. (1970). Part 14. Saurischia. Handbuch der Paläoherpetologie/Encyclopedia of Paleoherpetology. Part 14. Gustav Fischer Verlag:Stuttgart, p. 1-87.
  8. ^ a b 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.
  9. ^ a b 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. ISBN 0-520-24209-2
  10. ^ Royo-Torres, R., Cobos, A., and Alcalá, L. (2006). A giant European dinosaur and a new sauropod clade. Science 314:1925-1927.

External links

Apatosaurinae

Apatosaurinae is the name of a subfamily of diplodocid sauropods that existed between 157 and 150 million years ago in North America. The group includes two genera for certain, Apatosaurus and Brontosaurus, with at least five species. Atlantosaurus and Amphicoelias might also belong to this group.Below is a cladogram of apatosaurinae interrelationships based on Tschopp et al., 2015.

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Brasilotitan

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Cetiosauridae

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Cetiosaurus

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Cetiosaurus was in 1842 the first sauropod from which bones were described and is the most complete sauropod found in England. It was so named because its describer, Sir Richard Owen, supposed it was a marine creature, initially an extremely large crocodile, and did not recognise it for a land-dwelling dinosaur. Because of the early description many species would be named in the genus, eventually eighteen of them. Most of these have now been placed in other genera or are understood to be dubious names, based on poor fossil material. The last is true also of the original type species, Cetiosaurus medius, and so C. oxoniensis was officially made the new type species in 2014. C. oxoniensis is based on three more or less complete specimens, discovered from 1868 onwards. Together they contain most of the bones, with the exception of the skull.

Cetiosaurus oxoniensis was a "primitive", quadrupedal, long-necked, small-headed herbivore. It had a shorter tail and neck than most sauropods. The forelimbs on the other hand, were relatively long. C. oxoniensis is estimated to have been about 16 metres (52 ft) long and to have weighed roughly 11 tonnes (12 short tons).

Diplodocinae

Diplodocinae is an extinct subfamily of diplodocid sauropods that existed from the Late Jurassic to Early Cretaceous of North America, Europe and South America, about 161.2 to 136.4 million years ago. Genera within the subfamily include Tornieria, Supersaurus, Leinkupal, Galeamopus, Diplodocus, Kaatedocus and Barosaurus.Cladogram of the Diplodocidae after Tschopp, Mateus, and Benson (2015).

Eomamenchisaurus

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Tambatitanis

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Wintonotitan

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