Extinct Brontosaurus May Make a Comeback

The famous, long-extinct Brontosaurus may make a comeback - or, at least its name will, according to a new study.

Researchers suggest in the journal PeerJ the long-necked dinosaur currently known as Apatosaurus excelsus is distinct enough from its Apatosaurian kin as to be a different dinosaur altogether. So after a century of exile, the iconic Brontosaurus may be resurrected and reinstated as its own unique genus.

"The big picture is, there are independent groups of researchers looking at these dinos and these relationships, and they are independently arriving at the same conclusion, that the diversity of this family of dinosaurs is greater than previously recognized," Matthew Mossbrucker, the director and curator of the Morrison Natural History Museum in Colorado, who was not involved in the new study, told Live Science.

In 1903, scientists decided Brontosaurus was a more complete specimen of a different dinosaur. However, many more specimens of plant-eating sauropod dinosaurs are now known, allowing scientists to carry out a more complete analysis of their bones.

The name Brontosaurus goes back to the turn of the 20th century, when paleontologist Othniel Charles Marsh first discovered the so-called "thunder lizard."

But Marsh's team ended up finding two long-necked sauropods. He named one Apatosaurus ajax (meaning "deceptive lizard") and the second Brontosaurus excelsus. But the Brontosaurus name did not last long. Further fossil examinations determined that A. ajax and B. excelsus were more closely related than Marsh had believed, and so it was better to lump them both in the same genus. And because Apatosaurus was named first, it was the one that was used under the rules of scientific naming, and the name Brontosaurus died out. (Scroll to read on...)

But now, in the new study, researchers claim that there really are enough differences between A. excelsus and A. ajax to put them back into separate genera.

They examined not only Apatosaurs, but all long-necks in the Diplodocidae family - a group that includes Apatosaurs as well as Diplodocuses. The researchers examined 477 different morphological traits from individual specimens found in museums throughout Europe and the United States.

Most notably, according to the fossil evidence, Apatosaurus would have had a wider, more robust neck than Brontosaurus, their most defining feature. That, plus several other differences, warrants the resurrection of Brontosaurus as a genus distinct from Apatosaurus.

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

It is only with numerous new findings of dinosaurs similar to Apatosaurus and Brontosaurus in recent years that it has become possible to reevaluate how different they actually were in their heyday.

However, it should be noted that this does not mean a landslide victory for Brontosaurus. Science is a process, Tschopp and his colleagues point out, so bringing back Brontosaurus will require a lot more debate in the future.

"It's going to be a long time before we get there, probably, but this paper is a big start in terms of getting the debate going," John Whitlock, an associate professor at Mount Aloysius College, who wasn't involved in the study, told The Washington Post. "At the end, though, we're going to be in a much better place in terms of truly understanding the evolution of the lineages we study, and that's exciting."

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