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.
Oplosaurus
The tooth is large, 85 mm (3.35 in) tall in total, with a spatulate crown 52 mm (2.05 in) tall, comparable to "Brachiosaurus"; it has a pointed tip, a slightly compressed form "cheek" to tongue, a slight convexity to the base of the tongue-facing side, and wear facets. It is vaguely like a "Brachiosaurus" tooth, which is why the genus has for a time been referred to the Brachiosauridae. Earlier, "Oplosaurus" was typically referred to "Pelorosaurus" following an opinion of Friedrich von Huene in 1909, although "Pelorosaurus" is based on fragmentary remains that do not include teeth, making it impossible to prove the identity. (See Naish and Martill (2001) for a good review of "Oplosaurus" and Wealden sauropods in general; here is a more recent informal summation of the state of work.)