​Brontosaurus is back

Brontosaurus, the long-necked plant-eating dinosaur, has always been a classroom favorite. Never mind that it was declassified as a genus all its own in 1903 and lumped under the name Apatosaurus. But now, thanks to a study out Tuesday in the journal PeerJ, the Brontosaurus has reclaimed its place in the paleontology pantheon.

Yes, folks, Brontosaurus is a dinosaur once again.

Here's a quick review of the history. In 1879, the paleontologist Othniel C. Marsh identified the first specimen of Brontosaurus excelsus in Wyoming. Two years earlier he had named the Apatosaurus ajax, two years later he named another species of Brontosaurus, and in 1883 he published the first reconstruction of a Brontosaurus skeleton. Because none of his specimens had been found with a complete skull, he reconstructed a hypothetical head based on comparisons with the similarly sized Camarasaurus.

Soon, the troubles began.

In 1903, another paleontologist, Elmer Riggs, argued that the differences between Apatosaurus and Brontosaurus were not great enough to classify them as two distinct genera. Since the latter was discovered later, it was wrapped into the fomer. After 24 short years in the spotlight, Brontosaurus was no more.

But somehow its reputation endured. In 1978, decades of questions about the true shape of the Apatosaurus skull -- was it more like a Diplodocus or a Camarasaurus? -- came to a head. And so was born the popular myth that Brontosaurus had been a mistake all along, that it was just an Apatosaurus with a Camarasaurus head.

Still, fans of the "thunder lizard" held strong, brandishing t-shirts, backpacks and coffee mugs emblazoned with the dinosaur that never was. And finally, this week, they have their vindication.

Researchers from Portugal, Italy and the U.K. collaborated to review massive datasets published as recently as 2014 and specimens of the dinosaur group Diplodocidae, which includes the iconic long-necked, long-tailed Diplodocus and Apatosaurus, among others. By carefully, painstakingly analyzing the particular shapes, angles and attachments of vertebrae and other bones, and using statistical calculations to quantify the differences between them, the authors clarified the taxonomy of diplodocid dinosaurs in their nearly 300-page paper.

But no finding is more exciting than what they called "the resuscitation of Brontosaurus as a distinct genus from Apatosaurus."

"Our research would not have been possible at this level of detail 15 or more years ago," said Emanuel Tschopp, who led the study as a Ph.D. student at Universidade Nova de Lisboa in Portugal. "In fact, until very recently, the claim that Brontosaurus was the same as Apatosaurus was completely reasonable, based on the knowledge we had."

Octavio Mateus, a professor who collaborated on the study, said, "this is the classic example of how science works. Especially when hypotheses are based on fragmentary fossils, it is possible for new finds to overthrow years of research."

Of course, we Brontosaurus lovers knew it all along.