In 1877, a paleontologist named Othniel Charles Marsh (1831-1899) discovered a new species of dinosaur with he named Apatosaurus, meaning "deceptive lizard." Two years later, he discovered what he believed to be another species of dinosaur. He named this one Brontosaurus, meaning "thunder lizard." When later paleontologists examined the two fossils, however, they determined that both skeletons belonged to the same animal class, one being an adult and one being a juvenile. Since the Apatosaurus was discovered and named first, it became the official name. The Brontosaurus, however, had captured the imagination of the public and continued to be preferred by the general public. It was not until the 1980s, when the United States Post Office was taken to task by paleontologists for issuing a stamp depicting the creature and using the improper name, that people even began to be aware of the controversy. Since that time, most dinosaur literature has begun using the proper name Apatosaurus, often with a footnote that these massive dinosaurs used to be called "Brontosaurus."