Brontosaurus is back!

This is Brontosaurus as researchers see it today, with a Diplodocus-like head.

BRONTOSAURUS (the “thunder lizard”), thanks to its size, shape and evocative name, has been one of the world’s most iconic dinosaurs. But since 1903, the scientific community had believed that the genus Brontosaurus was a misnomer. The differences between Apatosaurus and Brontosaurus were so minor that the two were classified under the same genus. As Apatosaurus was named first, its name was the one that was used; Brontosaurus was known as Apatosaurus excelsus.

Now, through an exhaustive study (published in the peer-reviewed open access journal PeerJ) that includes almost 300 pages of evidence, the palaeontologists Emanuel Tschopp, Octávio Mateus and Roger Benson show that Brontosaurus is distinct from Apatosaurus after all—the “thunder lizard” is back!

How can a single study overthrow more than a century of research? “Our research would not have been possible at this level of detail 15 or more years ago,” said Tschopp, who led the study while doing his PhD at Universidade Nova de Lisboa in Portugal. “In fact, until very recently, based on the knowledge we had, the claim that Brontosaurus was the same as Apatosaurus was completely reasonable. It is only with numerous new findings of dinosaurs similar to Apatosaurus and Brontosaurus in recent years that it has become possible to undertake a detailed reinvestigation of how different they actually were.”

In science, the distinction between species and genera is without clear rules. Does this mean that the decision to resurrect Brontosaurus is just a matter of personal preference? “Not at all,” said Tschopp. The researchers applied statistical approaches to calculate the differences between other species and genera of diplodocid dinosaurs and were surprised by the result. “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 Benson, who is from the University of Oxford, U.K. Therefore, the researchers concluded that it was possible to resurrect Brontosaurus as a genus distinct from Apatosaurus. “It’s the classic example of how science works,” said Mateus. “Especially when hypotheses are based on fragmentary fossils, it is possible for new finds to overthrow years of research.”