The Brontosaurus is well-known and popular in children's stories, but it has actually been considered "misclassified" since 1903. New research provides conclusive evidence the long-necked dinosaur belongs to its own genus after all.
In the past, scientists claimed the Brontosaurus was a misnomer, and should actually be referred to as Apatosaurus, PeerJ reported. These researchers claimed the differences between Brontosaurus excelsus and Apatosaurus were so small that both should be classified in the same genus. Since Apatosaurus was named first, it was the one that stuck due to the rules of scientific naming.
In the 1870s field crews found several fossils of previously undescribed species in the Western United States, mostly in excavations for the paleontologists Marsh and Cope. Marsh's team uncovered two partial skeletons of long-necked dinosaurs. The first was described as Apatosaurus ajax or "deceptive lizard," the second as Brontosaurus excels, or "noble thunder lizard.
Neither skeletons was discovered with a skull, so the team reconstructed one for Brontosaurus excelsus, which is also similar to the Camarasaurus. Since these fossils were so similar, it seemed logical that Brontosaurus had a boxy skull like the Camarasaurus'; this theory was later determined to be incorrect.
Shortly after Marsh's death, another skeleton was found that had features consistent with both Apatosaurus ajax and Brontosaurus excelsus. This finding prompted scientists to conclude the two dinosaurs should be classified as different species within the same genus. Brontosaurus excelsus became known as Apatosaurus excelsus following the discovery, and the name Brontosaurus was thrown away.
Later, in the 1970s, researchers determined Apatosaurus was not closely related to Camarasaurus, but instead to another dinosaur called Diplodocus. This finding suggested the Apatosaurus actually had a slender horse-like skull similar to that of Diplodocus instead of Camarasaurus, leading to the now debunked idea that "Brontosaurus" was an Apatosaurus with the wrong head.
An exhaustive new study has now determined Brontosaurus was distinct from Apatosaurus after all. To make their findings, a team of researchers applied statistical approaches to calculate the differences between other species and genera of diplodocid dinosaurs.
"The differences we found between Brontosaurus and Apatosaurus were at least as numerous as the ones between other closely related genera, and much more than what you normally find between species," said Roger Benson, a co-author from the University of Oxford.
The study determined it is possible to resurrect the Brontosaurus as its own distinct genus from Apatosaurus.
"It's the classic example of how science works," said Professor Mateus, a collaborator on the research. "Especially when hypotheses are based on fragmentary fossils, it is possible for new finds to overthrow years of research."
The findings were published in a recent edition of the journal