Brontosaurus

Brontosaurus were a species of dinosaur. Apatosaurus were sometimes mistaken for Brontosaurus. (TV: Invasion of the Dinosaurs, Robot)

In an alternate timeline Brontosaurus was one of the dinosaurs brought back from extinction by the Silurians, it was mentioned that they were plentiful across France along with Diplodocus and also hunted by predators. (PROSE: Blood Heat)

According to one account, Brontosaurus were a fictional species. Jason guarded the Galactic Prison with many fictional species, including Brontosaurus. (PROSE: Head Games)

Behind the scenes
The scientific community considered Brontosaurus to be a fictional species for over a century, but a 2015 study concluded that Brontosaurus was a real species. Before then, all the fossils of it were falsely believed to be simply mistakenly identified Apatosaurus fossils.