It has been scientifically proven that brontosauruses never existed. The skeleton of what was believed to be a brontosaurus actually consisted of bones from several other prehistoric animals, with a skull and feet from one species and the rest of the skeleton from an apatosaurus..
The apatosaurus was already a known species when brontosauruses were first named. The specimen believed to be a brontosarus was larger than any previously discovered apatosaurus. As a result when the hybrid skeleton was first displayed in 1905, it was labeled as a brontosaurus. Two years earlier, Elmer Riggs discovered that apatosauruses and most brontosauruses were the same species. Because the name "apatosaurus" was in use earlier, when the two dinosaurs were discovered to be the same species, the brontosaurus was renamed apatosaurus. The proper skull was not paired with the rest of an apatosaurus skeleton until 1970.