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.
Spinosauridae
Although reliable size and weight estimates for most taxa are hindered by the lack of good material, all known spinosaurids were large animals. The smallest, "Irritator", was between 6 and 8 meters in length and 1 tonne (1.1 short tons) in weight. While "Ichthyovenator", "Baryonyx", and "Suchomimus" ranged from 7.5 to 11 meters long, and weighing between 1 and 5.2 tonnes (1.2 and 5.7 short tons). "Spinosaurus" was the largest, capable of reaching lengths over 15 meters (49 ft) and weighing between 7 and 20.9 tonnes (7.7 and 23.0 short tons),even though the latest estimates suggest a weight of 6.4–7.2 tonnes (7.1–7.9 short tons). This consistency in large body size among spinosaurids could have evolved as a byproduct of their preference for semiaquatic lifestyles, as without the need to compete with other large theropods for food, they would have been able to grow to tremendous lengths.