Brontosaurus
"Brontosaurus" was a large, long-necked quadrupedal animal with a long, whip-like tail, and forelimbs that were slightly shorter than its hindlimbs. The largest species, "B. excelsus", weighed up to and measured up to long from head to tail. For comparison, the current largest land animal, the average male African bush elephant is 3.20 m (10.5 ft) tall at the shoulder and has a body mass of 6,000 kg (13,228 lb) or 6.6 short tons.
Brachiosauridae
In addition, the characteristic long necks of brachiosaurids are distinct from those of other long-necked dinosaur taxa. They possessed a narrow neck composed of twelve to thirteen extremely long cervical vertebrae that was laterally inflexible and dorsoventrally, vertically, flexible. This meant that brachiosaurids could angle their necks up and lift their heads, enabling them to graze from treetops up to a height of about fourteen meters. It has been argued that other sauropods lacked this dorsoventral flexibility and that their necks stretched outwards in front of them instead of upwards. Brachiosaurids have more often been found in the conifer-rich sites, like the Tendaguru, than in the Morrison deposits, suggesting that their fitness was increased by the presence of taller conifer food sources.