Brontosaurus (Bron-toe-soar-us) is, perhaps, the most famous of all dinosaurs. The name means "thunder lizard" and evokes an image of a creature so large that the earth literally "thundered" when the dinosaur walked. This, of course, is a somewhat fanciful suggestion, but definitely captures the imagination. Although big, Brontosaurus was not the largest sauropod. Diplodocus (De-plod-i-cuss) was longer from head to tail and Brachiosaurus (Brack-ee-oh-soar-us) stood taller.
The scientific name "Brontosaurus," although well-known to the public, is no longer considered to be valid by scientists. The proper scientific name for this dinosaur is Apatosaurus (A-pat-oh-soar-us). The reason for this change in the name was essentially because the dinosaur was "discovered" twice: the first specimen was given the name Apatosaurus and the second specimen (discovered two years later) was dubbed Brontosaurus. It was not realized that they were actually both the same kind of dinosaur! According to the rules of science, the first name given (Apatosaurus in this case) is regarded as the correct name. For the purposes of this web site, however, the more popular name, Brontosaurus, will be used.
Brontosaurus lived during the Jurassic Period of western North America, approximately 150 million years ago. The average length of this dinosaur was about 75 feet, making it one of the largest land animals to have ever lived. As indicated above, however, it was not the largest sauropod dinosaur.
For many years, the head of Brontosaurus was unknown since the available skeletons all lacked a skull. It was assumed that the skull would be similar to that of Camarasaurus (Camera-soar-us), since scientists believed that this was a very close relative of Brontosaurus. Older reconstructions (pictures and even mounted skeletons), therefore, have a head very much like that of this dinosaur. As it turned out, however, Brontosaurus was much more closely related to Diplodocus. Indeed, a Diplodocus-like skull had been found near Brontosaurus specimens, but it was not known whether or not it belonged to them. We now know that the skull of Brontosaurus was elongated, with the nostrils placed high up on top of the head, between the eyes.
Skeleton of Brontosaurus (Apatosaurus) in the Carnegie Museum of Natural History