Every kid's dinosaur book had a Brontosaurus in it, right up until paleontologists decided the skeleton was actually a misidentified Apatosaurus with the wrong skull attached. That correction stuck for decades and became its own bit of smug trivia -- technically, Brontosaurus 'never existed.' Except a detailed 2015 reassessment of the actual bones found real anatomical differences, enough to justify bringing the name back as its own genus. The dinosaur you loved as a kid got reinstated, name and all.
What you were taught
Brontosaurus is a real dinosaur species
What we know now
Brontosaurus was long treated as a misidentified Apatosaurus, but a 2015 reassessment argued that Brontosaurus is distinct enough to be recognized again as its own genus. The real myth is that the name was permanently invalidated.
Updated understanding emerged around 2015