Diplodocus ("double beam"[1]) was a sauropod dinosaur that lived in the Late Jurassic Period of North America. It was named for its double-beamed chevron bones present on the ventral area of its tail. It is one of the best known sauropod dinosaurs.


Diplodocus is the longest dinosaur known from a complete skeleton[2], measuring over 35 meters long[3] (of which the neck represents 6 meters[4]) and 10 to 16 tonnes.[5][6][7][8]



Diplodocus had an extremely long tail, around 21 meters long, like many diplodocids it was related to. There has been much speculation about its purpose, the most popular theories being as a counterbalance to the enormous neck, using it for defense[9], or using it to create noise.[10]

Diplodocus had a tiny skull compared to its length. It had peg-shaped teeth that were present only in the front of the mouth[11], used for raking in plant matter. Its braincase was also small.

Diplodocus may have had thin spines lining its back, and many modern reconstructions show this feature.[12]


Diplodocus gives its name to its family of Diplodocidae. Other genera in the family include Barosaurus and Apatosaurus.[13]


Diplodocus was first discovered in Colorado in 1877. It was described the next year by Othniel Charles Marsh as Diplodocus longus.[14] Since then, three other species have been found in the Morrison Formation of western America, namely D. carnegii, the most well known species.

In 1991, a species was named as Seismosaurus halli, reputed to be one of the longest dinosaurs ever. Because the species name halli was not the correct gender for the name, there were attempts to rename it S. hallorum.[15] It was eventually renamed Diplodocus hallorum in 2006, and may even be the same as D. longus.[16]


Diplodocus is one of the best-studied dinosaurs, due to its popularity and wealth of skeletal material available.



Outdated reconstruction of neck and posture


Current restoration of neck and posture

A famous drawing of Diplodocus by Oliver Hay depicts it with sprawled limbs rather like a lizard's.[17] However, W.J. Holland argued that for the dinosaur to maintain such a position it would have to walk over a trench all of its life.[18] The theory has since been discarded after footprints were found in the 1930s, and Diplodocus is now believed to have walked upright like other dinosaurs with its limbs held under its body.


Diplodocids were once thought to hold their necks high up in the air like Brachiosaurus and its kin. However, computer models suggest that a Diplodocus's neck was naturally held in a horizontal position.[19] Further studies suggested all tetrapods naturally held their neck at the maximum possible vertical extension (in the absence of any structures hindering or preventing this), which contradicts the computer models entirely.[20] The debate remains unsolved.

It was suggested in 2006 that the long necks of sauropods including Diplodocus were used for sexual selection, as opposed to the traditional theory of feeding benefits.[21] The suggestion has since been refuted.[22]


It was originally believed that Diplodocus (and some other sauropods) was aquatic, due to its sheer size and position of the nasal openings.[23] However, it has since been shown that the water pressure would crush the chest of the animal[24], and the nostrils are now believed to have been located at the end of the snout like most other dinosaurs.[25] Diplodocus is now believed to have been terrestrial, in habitats with adequate vegetation.


Diplodocids had peg-shaped teeth which were likely used to strip leaves off of trees instead of biting them off.[26] They may have also been able to rear up on their hind legs to reach high branches.[27]

In 2010, a juvenile Diplodocus was found to have teeth located lining the whole jaw, instead of only at the front, highlighting a difference between adults and young that was not previously seen in sauropods.[28]

In popular cultureEdit

Becoming one of the more famous dinosaurs after Andrew Carnegie supplied specimen casts to museums around the world, Diplodocus has appeared in several movies and television programs including Walking with Dinosaurs.


  1. Simpson, John; Edmund Weiner (eds.) (1989). The Oxford English Dictionary (2nd ed.). Oxford: Oxford University Press. ISBN 0-19-861186-2.
  2. Lambert D. (1993)The Ultimate Dinosaur Book ISBN 0-86438-417-3
  3. Upchurch P, Barrett PM, Dodson P (2004). "Sauropoda". In Weishampel DB, Dodson P, Osmólska H. The Dinosauria (2nd Edition). University of California Press. pp. 305. ISBN 0-520-24209-2.
  4. Upchurch P, Barrett PM, Dodson P (2004). "Sauropoda". In Weishampel DB, Dodson P, Osmólska H. The Dinosauria (2nd Edition). University of California Press. pp. 316. ISBN 0-520-24209-2.
  5. Dodson, P., Behrensmeyer, A.K., Bakker, R.T., and McIntosh, J.S. (1980). Taphonomy and paleoecology of the dinosaur beds of the Jurassic Morrison Formation. Paleobiology 6:208–232.
  6. Paul, G.S. (1994). Big sauropods – really, really big sauropods. The Dinosaur Report, The Dinosaur Society Fall:12–13.
  7. Foster, J.R. (2003). Paleoecological Analysis of the Vertebrate Fauna of the Morrison Formation (Upper Jurassic), Rocky Mountain Region, U.S.A. New Mexico Museum of Natural History and Science:Albuquerque, New Mexico. Bulletin 23.
  8. Coe, M.J., Dilcher, D.L., Farlow, J.O., Jarzen, D.M., and Russell, D.A. (1987). Dinosaurs and land plants. In: Friis, E.M., Chaloner, W.G., and Crane, P.R. (eds.). The Origins of Angiosperms and Their Biological Consequences. Cambridge University Press:New York, 225–258. ISBN 0-521-32357-6.
  9. Holland WJ (1915). "Heads and Tails: a few notes relating to the structure of sauropod dinosaurs". Annals of the Carnegie Museum 9: 273–278.
  10. Myhrvold NP and Currie PJ (1997). "Supersonic sauropods? Tail dynamics in the diplodocids". Paleobiology 23: 393–409.
  11. Upchurch, P. & Barrett, P.M. (2000). Chapter 4: The evolution of sauropod feeding mechanism. IN: Evolution of Herbivory in Terrestrial Vertebrates ISBN 0-521-59449-9
  12. Czerkas, S. A. (1994). "The history and interpretation of sauropod skin impressions." In Aspects of Sauropod Paleobiology (M. G. Lockley, V. F. dos Santos, C. A. Meyer, and A. P. Hunt, Eds.), Gaia No. 10. (Lisbon, Portugal).
  13. Marsh, O.C. 1884. Principal characters of American Jurassic dinosaurs. Part VII. On the Diplodocidae, a new family of the Sauropoda. American Journal of Science 3: 160–168.
  14. Marsh OC. Principal characters of American Jurassic dinosaurs. Part I. American Journal of Science 3; 411–416 (1878).
  15. Carpenter, K. (2006). "Biggest of the big: a critical re-evaluation of the mega-sauropod Amphicoelias fragillimus." In Foster, J.R. and Lucas, S.G., eds., 2006, Paleontology and Geology of the Upper Jurassic Morrison Formation. New Mexico Museum of Natural History and Science Bulletin 36: 131–138.
  16. Lucas, S.G., Spielman, J.A., Rinehart, L.A., Heckert, A.B., Herne, M.C., Hunt, A.P., Foster, J.R., and Sullivan, R.M. (2006). "Taxonomic status of Seismosaurus hallorum, a Late Jurassic sauropod dinosaur from New Mexico". In Foster, J.R., and Lucas, S.G.. Paleontology and Geology of the Upper Morrison Formation. New Mexico Museum of Natural History and Science (bulletin 36). pp. 149–161. ISSN 1524-4156.
  17. Hay, Dr. Oliver P., "On the Habits and Pose of the Sauropod Dinosaurs, especially of Diplodocus." The American Naturalist, Vol. XLII, Oct. 1908
  18. Holland, Dr. W. J., "A Review of Some Recent Criticisms of the Restorations of Sauropod Dinosaurs Existing in the Museums of the United States, with Special Reference to that of Diplodocus carnegii in the Carnegie Museum", The American Naturalist, 44:259–283. 1910.
  19. Stevens KA, Parrish JM (2005). "Neck Posture, Dentition and Feeding Strategies in Jurassic Sauropod Dinosaurs". In Carpenter, Kenneth and Tidswell, Virginia (ed.). Thunder Lizards: The Sauropodomorph Dinosaurs. Indiana University Press. pp. 212–232. ISBN 0-253-34542-1.
  20. Taylor, M.P., Wedel, M.J., and Naish, D. (2009). "Head and neck posture in sauropod dinosaurs inferred from extant animals". Acta Palaeontologica Polonica 54 (2), 2009: 213–220 abstract
  21. Senter, P. "Necks for Sex: Sexual Selection as an Explanation for Sauropod Neck Elongation". Journal of Zoology, 2006
  22. Taylor, M.P., Hone, D.W.E., Wedel, M.J. and Naish, D. (2011). "The long necks of sauropods did not evolve primarily through sexual selection." Journal of Zoology doi:10.1111/j.1469-7998.2011.00824.x
  23. Hatcher JB. "Diplodocus (Marsh): Its osteology, taxonomy, and probable habits, with a restoration of the skeleton,". Memoirs of the Carnegie Museum, vol. 1 (1901), pp. 1–63
  24. Kermack, Kenneth A. (1951). "A note on the habits of sauropods". Annals and Magazine of Natural History 12 (4): 830–832.
  25. Lawrence M. Witmer et al., "Nostril Position in Dinosaurs and other Vertebrates and its Significance for Nasal Function." Science 293, 850 (2001)
  26. Norman, D.B. (1985). "The illustrated Encyclopedia of Dinosaurs". London: Salamander Books Ltd
  27. Barrett, P.M. & Upchurch, P. (2005). Sauropodomorph Diversity through Time, Paleoecological and Macroevolutionary Implications. IN: "The Sauropods: Evolution and Paleobiology" (Eds. Curry, K. C.)
  28. Whitlock, John A.; Wilson, Jeffrey A. & Lamanna, Matthew C. (March 2010). "Description of a Nearly Complete Juvenile Skull of Diplodocus (Sauropoda: Diplodocoidea) from the Late Jurassic of North America". Journal of Vertebrate Paleontology (2) 30 (2): 442–457. doi:10.1080/02724631003617647.

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