Quick—name a big, long-necked dinosaur. For a lot of people, the first word to come to mind is “Brontosaurus.” But for most of the past hundred years, that’s been incorrect. The reason why has to do with how scientists name new species.

In 1877, one scientist found a long-necked dinosaur and named it Apatosaurus. In 1877, another scientist found another long-necked dinosaur and named it Brontosaurus. But later paleontologists looking at Brontosaurus fossils determined that they were actually the same kind of dinosaurs as Apatosaurus. And since the name Apatosaurus was in use before Brontosaurus, Apatosaurus became the name used. “Brontosaurus” was no longer the correct name for Apatosaurus, but it stuck around in public memory, so some people still used it.

A couple years ago, though, a new group of scientists suggested that Brontosaurus might actually be a separate kind of dinosaur after all. Paleontologists haven’t come to agreement yet—there’s always new things being discovered and rediscovered in science!

Photo by Priscilla Jordão