Brontosaurus makes a comeback
Brontosaurus has come thundering back after being sent into exile by the scientific community.
The giant dinosaur and its evocative name - meaning "thunder lizard" - has enthralled generations of youngsters.
But since 1903, experts have believed the creature was originally misnamed. Instead of belonging to the genus, or species "family" Brontosaurus, it should in fact have been classified as "Apatosaurus" - which does not have quite the same ring.
Over the decades, the Brontosaurus moniker has stuck, at least with children. And now new research has shown that it is, after all, sufficiently different from Apatosaurus to deserve its own genus name. The thunder lizard is back.
Scientists from the UK and Portugal submitted the evidence for resurrecting Brontosaurus in a study almost 300 pages long published in the open access journal PeerJ.
Dr Roger Benson, one of the authors from Oxford University, said: "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."
Colleague Emanuel Tschopp, from Nova de Lisboa University in Portugal, said: "Our research would not have been possible at this level of detail 15 or more years ago. In fact, until very recently, the claim that Brontosaurus was the same as Apatosaurus was completely reasonable, based on the knowledge we had."
The history of Brontosaurus is both complex and intriguing.
In the 1870s, palaeontologists led by Othniel Charles Marsh discovered two enormous partial skeletons of long-necked dinosaurs in the US and shipped them to the Yale Peabody Museum in New Haven, Connecticut.
Marsh described the first of the creatures as Apatosaurus ajax, the "deceptive lizard", after the Greek hero Ajax. Two years later, he named the second skeleton Brontosaurus excelsus, the "noble thunder lizard".
Neither skeleton was found with a skull, and Marsh reconstructed one for Brontosaurus excelsus. However, his reconstruction, based on evidence from another long-necked dinosaur, Camarasaurus, was later found to be wrong.
Shortly after Marsh's death, scientists from the Field Museum of Chicago found another skeleton similar both to Apatosaurus and Brontosaurus. In fact they were so similar that experts decided it would be correct to treat them as two species from the same genus: Apatosaurus.
The final blow to Brontosaurus came in the 1970s when researchers showed that Apatosaurus/Brontosaurus was not closely related to Camarasaurus but Diplodocus, another dinosaur from the same era.
Diplodocus had a slender, horse-like skull, not the box-like one reconstructed by Marsh and modelled on Camarasaurus. Thus the myth was born that Brontosaurus was actually an Apatosaurus with the wrong head.
For the new study the researchers used statistical techniques to calculate the differences between species and genera of "diplodocid" dinosaurs - a group that included some of the longest animals that ever walked on the Earth.
Two members of the group, Diplodocus and Supersaurus, may have reached lengths of up to 34 metres (112 ft). Apatosaurus, also from the group, had an average length of 22.8 metres (75 ft), and weighed around 16.4 tonnes.