Since the early 1900s, paleontologists have believed that the dinosaur genus Brontosaurus (thunder lizard) was in fact the Apatosaurus. Now, a new study, led by Dr Emanuel Tschopp of the Universidade Nova de Lisboa, the Museu da Lourinhã, Portugal, and the Universita di Torino, Italy, provides evidence that Brontosaurus is distinct from Apatosaurus and as such can now be reinstated as its own unique genus.
Illustration of Brontosaurus in the water, and Diplodocus on land, by Charles R. Knight, 1897.
Brontosaurus is one of the most charismatic dinosaurs of all time, inspiring generations of children thanks to its size and evocative name. However, as every paleontologist knows, Brontosaurus was in fact a misnomer, and it should be correctly referred to as Apatosaurus.
At least, this is what paleontologists have believed since 1903, when it was decided that the differences between Brontosaurus excelsus and Apatosaurus were so minor that it was better to put them both in the same genus.
Because Apatosaurus was named first, it was the one that was used under the rules of scientific naming.
In fact, of course, the Brontosaurus was never really gone – it was simply treated as a species of the genus Apatosaurus – A. excelsus.
So, while scientists thought the genus Brontosaurus was the same as Apatosaurus, they always agreed that the species excelsus was different from other Apatosaurus species.
Now, Dr Tschopp and his colleagues have shown that Brontosaurus was a unique genus all along.
“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,” said Dr Tschopp, who is the first author of the paper published in the journal PeerJ.
History of Brontosaurus – one of the greatest stories in paleontology. Image credit: PeerJ.
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.
“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 co-author Dr Roger Benson of the University of Oxford, UK.
Therefore, the scientists have concluded that it’s now possible to resurrect Brontosaurus as a genus distinct from Apatosaurus.
“It’s 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,” said study co-author Prof Octávio Mateus of the Universidade Nova de Lisboa and the Museu da Lourinhã.
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Tschopp E et al. 2015. A specimen-level phylogenetic analysis and taxonomic revision of Diplodocidae (Dinosauria, Sauropoda). PeerJ 3: e857; doi: 10.7717/peerj.857
