Diplodocid

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 .
With their peg-like teeth they could strip leaves from branches, and leave the grinding to gastroliths. They bacteria in their vast stomachs would break down the cellulose in the leaves, and the product would be absorbed further on in the alimentary canal.
The diplodocids have two sub-families:
Their cousins the brachiosaurs are put into a sister family. The much later titanosaurs were the last group of sauropods on Earth.