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.
Brontosaurus
In 1879, O.C. Marsh, a professor of paleontology at Yale University, announced the discovery of a large and fairly complete sauropod skeleton from Morrison Formation rocks at Como Bluff, Wyoming. He identified it as belonging to an entirely new genus and species, which he named "Brontosaurus excelsus",
Elmer Riggs, in the 1903 edition of "Geological Series of the Field Columbian Museum", argued that "Brontosaurus" was not different enough from "Apatosaurus" to warrant its own genus, so he created the new combination "Apatosaurus excelsus" for it. Riggs stated that "In view of these facts the two genera may be regarded as synonymous. As the term 'Apatosaurus' has priority, 'Brontosaurus' will be regarded as a synonym". Nonetheless, before the mounting of the American Museum of Natural History specimen, Henry Fairfield Osborn chose to label the skeleton "Brontosaurus", though he was a strong opponent of Marsh and his taxa.