Diplodocus

Diplodocus is one of the best-known sauropods (long-necked herbivorous dinosaurs) of the late Jurassic Period. It lived in western North America about 155.7 million to 150.8 million years ago.

In addition to its unique body construction, Diplodocus had two rows of bones under its tail to provide greater mobility and support.
Diplodocus' mass is estimated between 11 and 17.6 tons (10 to 16 metric tons), which is within the range accepted by modern palaeontologists.

An almost-complete skeleton of the best-known Diplodocus species measures 90 feet (27.4 meters) long. Largest species measured approximately 108 feet (33 meters).

Its neck and tail accounted for most of Diplodocus' length. The neck alone measured 21 feet (6.5 meters), and the tail measured even more.