Diplodocoidea

Diplodocoidea was a superfamily of sauropod dinosaurs, which included some of the longest animals of all time, including slender giants like Supersaurus, Diplodocus, Apatosaurus, and Amphicoelias. Most had very long necks and long, whip-like tails; however, one family (the dicraeosaurids) are the only known sauropods to have re-evolved a short neck, presumably an adaptation for feeding low to the ground. This adaptation was taken to the extreme in the highly specialized sauropod Brachytrachelopan.

Taxonomy
Infraorder Sauropoda
 * Superfamily Diplodocoidea
 * Amazonsaurus
 * Rebbachisauroidea
 * Histriasaurus
 * Family Rebbachisauridae
 * Cathartesaura
 * Limaysaurus
 * Nigersaurus
 * Nopcsaspondylus
 * Rayososaurus
 * Rebbachisaurus
 * Flagellicaudata (whip-tails)
 * Family Dicraeosauridae
 * Amargasaurus
 * Brachytrachelopan
 * Dicraeosaurus
 * Suuwassea
 * Family Diplodocidae
 * ?Amphicoelias
 * Cetiosauriscus
 * Dinheirosaurus
 * Subfamily Apatosaurinae
 * Apatosaurus
 * Eobrontosaurus
 * Supersaurus
 * Subfamily Diplodocinae
 * Barosaurus
 * Diplodocus