Diplodocidae

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, which may have reached lengths of up to 34 m (112 ft.), and the gigantic Amphicoelias, known from a single vertebra representing an individual that may have exceeded 40 meters (131 ft) or reached 60 (201 ft).