Brontosaurus is one of the more famous dinosaur genera, despite the fact that it was recognized as the exact same genus as Apatosaurus even before Webster 1913 went to print. Apatosaurus remains the proper name. Discovered by Othniel Marsh in 1879, the Brontosaurus was first distinguished from the Apatosaurus by the number of fused vertebrae in the sacrum – the larger Brontosaurus had five, while the Apatosaurus had only three. For a long time scientists assumed that these immense animals were aquatic, but eventually it was discovered that creatures of this size could handle living on land.

Brontosaurus was most probably was named after the mythical Cyclops Brontes rather than for the sound the "thunder lizard" made while walking. By 1903, it was clear that Brontosaurus was in actuality nothing more than an adult Apatosaurus; the original Apatosaurus remains were not fully grown. Although the name Brontosaurus had a legimate claim to the lizard (underdeveloped fossils are usually not grounds for naming a new genus, and the Brontosaurus find was more complete), the Apatosaurus name was older and more established.

Equally disappointing for kids, not only does the Brontosaurus not officially exist, but it may have always kept its long neck near the ground. Apparently the structure of the neck makes the long-held "stretching for the top leaves" evolutionary theory impossible. This new finding is still the subject of heated debate, proving that, more than one hundred years about its discovery, we still know very little about the Brontosaurus.

See Apatosaurus for more about this gentle giant.