Stop all, the brontosaurus (maybe) is back. For over a century textbooks have told us that the gigantic herbivore, one of the most famous dinosaurs of all time along with the fearsome Tyrannosaurus rex, was the result of a taxonomic oversight. A new study, published in the journal PeerJ, is now reversing: the Brontosaurus is not an Apatosaurus classified incorrectly - as previously believed - but a sauropod in its own right that lived about 150 million years ago.

Brontosaurus, indeed no. In 1877 the American paleontologist Othniel Charles Marsh discovered a partial fossil of a herbivore about 15 meters long, which was renamed as Apatosaurus. Two years later, the same Marsh brought to light an almost complete skeleton of an even larger dinosaur, over 20 meters long: he called it Brontosaurus, or "thundering lizard", to underline the sound of its heavy walk.

Apatosaurus 24 meters long, 8 meters high and weighing 35 tons: the Apatosaurus (up to now synonymous with Brontosaurus) is one of the largest dinosaurs ever to appear on Earth. | Natural History Museum (WAC) / Nature Picture Library / contrast

In 1903, a few years after Marsh's death, however, the cold shower came: the studies of the paleontologist lmer Riggs, of the Field Museum of Chicago, established that Apatosaurus and Brontosaurus were actually the same animal and that the first finding was simply a specimen younger. For matters of taxonomic precedence, the scientific community officially opted for the name Apatosauros, a choice that did not prevent the brontosaurus from establishing itself in pop culture, becoming in fact one of the most famous - and cited - dinosaurs of all time.

Apatosaurus to whom? A team of paleontologists from the University of Oxford and the Universidade Nova of Lisbon has now used a statistical method to compare 477 anatomical features from 81 fossil records cataloged in various databases. According to the three authors of the study between Brontosaurus and Apatosaurus there are enough differences to legitimize the classification made by Marsh at the end of the nineteenth century. Moral, brontosaurus can again be considered by science as an autonomous genus in the diplodocid family (although some paleontologists may also disagree).

As the researchers themselves point out, the discovery serves not only to give back to the brontosaurus the dignity it deserves, but it is also yet another demonstration that new technologies can play a key role in understanding species that have been extinct for millions of years.

Head of Apatosaurus The skull of "Einstein", the extraordinary Apatosaurus skeleton discovered in 2005 in the United States, with 85% of the bones still intact. | REUTERS / Tomas Bravo

Headless giant. Despite the latest implications, the troubled history of the Brontosaurus is still far from a definitive closure. Once the taxonomic separation has been established, it remains now to understand what was the real aspect of this gigantic herbivore. If there is no doubt about the massive build, the long neck and the whip tail, a piece is still missing to complete the mosaic: the head.

When, in 1879, Marsh unearthed the remains of the Brontosaurus, he realized that the animal's head was missing and, on the wings of enthusiasm, he chose without asking too many questions a shortened skull found in the area. A century later, two other researchers, McIntosh and Berman, decreed that the skull in question belonged to another dinosaur, the Camarasauru s - a revelation that agreed with the fact that the skull of the Apatosaurus was long and flattened.

Now that Apatosaurus and Brontosaurus are no longer the same animal there is therefore a gap: what will be the true "face" of sauropod? According to Tschopp and colleagues, the answer will come from the latest finds of diplodocide skeletons, whose details will be revealed in the near future.