It's BRONTOSAURUS!
Way back, when scientists were madly digging up and naming dinosaurs, bearded paleontologist Othniel Charles Marsh dug up and named a massive sauropod. He called it "apatosaurus," which means "deceptive lizard." Very few people felt the urge to say that name more than once. The dinosaur was a flop.
Professor Marsh soon dug up and named another similar sauropod: the brontosaurus. “Brontosaurus” means "thunder lizard." This is the sauropod you've heard of.
But trouble was brewing for brontosaurus. Some guy named Elmer — a hairless man from Kansas — reviewed the two specimens and declared them the same species. Scientists abandoned the second, better name.
Unperturbed, brontosaurus went on to great success, dominating lunch boxes, gas stations and casual conversation for the next hundred years. Meanwhile, dorks everywhere delighted in the opportunity to correct preschoolers on their nomenclature.
In 2015 vindication arrived for brontosaurus when a team of smarter, modern scientists confirmed what children and film producers everywhere already knew, BRONTOSAURUS! is a real, fancy creature with great creative instincts, a knack for thriving in unconventional circumstances, and one keen eye.
In the end, Othniel Charles Marsh was returned to glory. Elmer, meanwhile, is dead.