Scientists shakeup in the dinosaur family tree. A British branch?
A newly proposed family tree aims to rewrite the history of some of the most famous dinosaurs. What do dino hips say about the family tree?
—The earliest dinosaurs may have roared with a British accent, according to a new study.
And that’s the least of the fallout from a newly proposed dinosaur family tree that upends and bulldozes the one that stood for the past 130 years. If lead author Matthew Baron and his colleagues are correct, dinosaurs may have emerged millions of years earlier than previously thought, and A-listers such as Tyrannosaurus rex and Velociraptor may have been misclassified. Oh, and the first dinosaurs could have come from England.
While genetic data gains ground as a method of determining how closely living species are related, most dinosaur DNA decayed millions of years ago, so scientists have to rely on the classic technique of comparing physical features, such as the shapes of bones.
One such pivotal divide hinges on hip shape, which has long split dinosaurs into two groups: those with hips like birds and those with hips like lizards. The bird-hipped Ornithischia group was made up of mostly plant eaters such as Stegosaurus and Triceratops, while the reptile-hipped Saurischia group welcomed those of all diets, including the vegetarian Brontosaurus and the carnivorous T. rex.
Mr. Baron’s new analysis, which draws on a much wider variety of samples than what was available a century ago, concluded that the meat eaters were out of place. It turns out that Ornithischia has always been a bit of a wild card, with hips that have been described as “enigmatically organized.” In the light of a number of new species discovered in just the past 30 years, Baron suggests paleontologists should actually consider those meat eaters to be members of the Ornithischia family.
This new place would resolve some longstanding mysteries, such as why many meat eaters show birdlike features, such as feathers, despite also having lizard-looking hips.
"It seems that the dinosaur family tree is being shaken quite firmly. It will be interesting to see what drops from its branches in years to come," Cambridge University’s David Norman, who supervised the study, told the BBC.
And fruit is falling already. The reorganization places two fossils in particular near the base of the new tree. These previously peripheral species, originally unearthed in Scotland and England, now find themselves in a role of central importance, suggesting that early dinosaurs first evolved 245 million years ago in what is now the United Kingdom, rather than 230 million years ago in today’s East Africa.
"A British scientist, Sir Richard Owen, gave the word dinosaur to the world. Now we may be looking at the possibility that the very earliest dinosaurs were roaming an area that has become Britain and the group itself could have originated on these shores," explained Baron.
But Great Britain and Ireland were unrecognizable back then. Part of the supercontinent Laurasia, they were crammed together with what is now North America and Eurasia into one giant landmass after the breakup of Pangea. This finding contradicts the established model, which proposes that dinosaurs emerged on the southerly supercontinent of Gondwana, which would go on to become South America, Africa, Australia, and New Zealand.
The new tree has plenty of critics as well. Hans Sues of the Smithsonian Museum in Washington, D.C., told the BBC that extraordinary claims require extraordinary evidence.
"I am skeptical as none of the other recent analyses obtained similar results – but I keep an open mind," he said.
Those involved with the study agree that such a huge claim needs independent verification.
"All the major textbooks covering the topic of the evolution of the vertebrates will now need to be re-written if this suggestion survives academic scrutiny and becomes accepted more widely," Dr. Norman said.
The team points out that the early dinosaur fossil record is quite thin, but hopes future discoveries will bear out their proposals.
The new classification did feature at least two prominent casualties. Under the updated tree, old favorites such as Brontosaurus and Diplodocus could no longer technically be called dinosaurs.
Perhaps learning from the public outcry over Pluto’s loss of status as a planet, Baron and his team carefully redefined their usage of the term "dinosaur" to avoid angering dino-fans.
"I didn't want to make Dippy not a dinosaur," said Baron, referring to the beloved Diplodocus skeleton in the lobby of London’s Natural History Museum. "That would have created a lot of upset. They are a very well known group and everyone has recognised them to be dinosaurs. To be truthful, I didn't want to be chased out of every conference I went to for the rest of my career."