Diplodocid

Diplodocids Temporal range: Middle Jurassic-Early Cretaceous, 170–136.4 Ma PreЄ Є O S D C P T J K Pg N
Diplodocus carnegii skeleton cast, Berlin Hauptbahnhof
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Reptilia
Clade:	Dinosauria
Order:	Saurischia
Suborder:	†Sauropodomorpha
Clade:	†Neosauropoda
Clade:	†Flagellicaudata
Family:	†Diplodocidae Marsh, 1884
Type species
†Diplodocus longus Marsh, 1878
Subgroups
†Amphicoelias †Apatosaurinae †Apatosaurus †Atlantosaurus †Brontosaurus †Diplodocinae †Barosaurus †Dinheirosaurus †Diplodocus †Galeamopus †Kaatedocus †Leinkupal †Supersaurus †Tornieria
Synonyms
Atlantosauridae? Marsh, 1877 Amphicoeliidae? Cope, 1878 Apatosauridae Huene, 1927

Diplodocids, or members of the family Diplodocidae ("double beams"), are a group of sauropod dinosaurs. The family includes some of the longest creatures ever to walk the Earth, including Diplodocus and Supersaurus, some of which may have reached lengths of up to 34 metres (112 ft).

While still massive, when compared to the titanosaurids and brachiosaurs, the diplodocids were relatively slender but extremely long. They had short legs, making them the "dachshund" of giant dinosaurs; and their rear legs were longer than front legs, giving their back a distinctive downward slope towards the neck.

Their necks were also extremely long. According to recent computer simulations, they may not have been able to lift their necks like other sauropods. However, these simulations do not take vertebral cartilage into account, which would likely allow a greater range of motion. Instead of reaching up into trees, they may have used their necks to graze over a broad area. They may also have used their necks to reach into dense stands of conifers, or over marshy ground.

Their heads, like those of other sauropods, were tiny with the nasal openings on the top of the head (though in life the nostrils themselves would have been close to the tip of the snout). Their teeth were only present in the front of the mouth, and looked like pencils or pegs. They probably used their teeth to crop off food, without chewing, and relied on gastroliths (gizzard stones) to break down tough plant fibers (similar to modern birds).

The heads of diplodocids have been widely depicted with the nostrils on top due to the position of the nasal openings at the apex of the skull. There has been speculation over whether such a configuration meant that diplodocids may have had a trunk. A 2006 study surmised there was no paleoneuroanatomical evidence for a trunk. It noted that the facial nerve in an animal with a trunk, such as an elephant, is large as it innervates the trunk. The evidence suggests that the facial nerve is very small in diplodocids. Studies by Lawrence Witmer (2001) indicated that, while the nasal openings were high on the head, the actual, fleshy nostrils were situated much lower down on the snout.

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